NIST

A 11107 Q5613S PUBLICATIONS

NBSIR 75-94b

The National Measurement

System for Surface Properties

C. J. Powell

Institute for Basic Standards

National Bureau of Standards

Washington, D. C. 20234

December 1 976

Final

Issued March 1 977

100 DEPARTMENT OF COMMERCE

>NAL BUREAU OF STANDARDS

NBSIR 75-945

THE NATIONAL MEASUREMENT

SYSTEM FOR SURFACE PROPERTIES

C. J. Powell

Institute for Basic Standards

National Bureau of Standards

Washington, D. C. 20234

December 1976

Final

Issued March 1 977

U.S. DEPARTMENT OF COMMERCE, Juanita M. Kreps, Secretary

Dr. Betsy Ancker-Johnson, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler. Acting Director

CONTENTS

EXECUTIVE SUMMARY 1 1. INTRODUCTION 3

2. STRUCTURE OF THE MEASUREMENT SYSTEM 6 2.1 Conceptual System 6 2.2 Basic Technical Infrastructure 7 2.2.1 Documentary Specification System 7 2.2.2 Instrumentation System 7 2.2.2.1 Measurement Tools and Techniques 7 2.2.2.2 The Instrumentation Industry 9 2.2.3 Reference Data 12 2.2.4 Reference Materials 13

2.2.5 Science and People 13

2.3 Realized Measurement Capabilities 14

2.3.1 Measurement of Surface Composition 14 2.3.2 Measurement of Surface Atomic Structure 17 2.3.3 Measurement of Electronic Structure of Surfaces 18, 2.3.4 Summary of Measurement Needs 18

2.4 Dissemination and Enforcement Network 19

2.4.1 Central Standards Laboratories 19

2.4.2 State and Local Offices of Weights and Measures 19

2.4.3 Standards and Testing Laboratories and Services 19

2.4.4 Regulatory Agencies 19

2.5 Direct Measurements Transactions Matrix 19

2.5.1 Analysis of Suppliers and Users 19

2.5.2 Highlights re Major Users 22

3. IMPACT, STATUS, AND TRENDS OF MEASUREMENT SYSTEM 22

3.1 Impact of Measurements 22

3.1.1 Functional, Technological, and Scientific Applications 22

3.1.1.1 Applications for Surface Science 22

3.1.1.2 Applications for Surface Technology 23

3.1.1.2.1 Government Laboratories 23

3.1.1.2.2 Semiconductor Industry 24

3.1.1.2.3 Chemical Industry 25

3.1.1.2.4 Petroleum Industry 25

3.1.1.2.5 Metallurgical Industry 25

3.1.1.2.6 Other Industries 27 3.1.1.3 Summary of Applications 27

3.1.2 Economic Impacts - Costs and Benefits 28

3.1.3 Social, Human, Man-on-the-Street Impacts 30

3.2 Status and Trends of the System 30

4. SURVEY OF NBS SERVICES 38

4.1 The Past 38

4.1.1 History of the Surface Physics Program 38

4.1.2 General Outputs of the Surface Physics Program 39

4.1.3 Specific Outputs of the Surface Physics Program 40

4.1.4 Cooperation between Surface Programs in the Institute for

Basic Standards and the Institute for Materials Research .... 40

4.1.5 Cooperation between Surface Programs in the Institute for

Basic Standards and the Institute for Applied Technology .... 43

4.2 The Present--Scope of NBS Services 43

4.2.1 Description of NBS Services 43

4.2.2 Users of NBS Services 43

4.2.3 Alternate Sources 44

4.2.3.1 Measurement Needs 44

4.2.3.1.1 Measurement Needs for the Determination

of Surface Composition 44

4.2.3.1.2 Measurement Needs for the Determination

of Surface Atomic Structure 45

4.2.3.1.3 Measurement Needs for the Determination

of Surface Electronic Structure 45
4.2.3.1.4 Measurement Needs for other Surface

Properties and Processes 46

4.2.3.2 Sources of Measurement Services 46

4.2.4 Funding Sources for NBS Services 49

4.2.5 Mechanism for Supplying Services 49

4.3 Impact of NBS Services 49

4.3.1 Economic Impact of Major User Classes 50

4.3.2 Technological Impact of Services 50

4.3.3 Payoff from Changes in NBS Services 50

4.4 Evaluation of NBS Program 50

4.5 The Future 51

5. SUMMARY AND CONCLUSIONS 51 APPENDIX A. METHODOLOGY OF THE STUDY 54

APPENDIX B. SUMMARY OF RECENTLY-PUBLISHED BACKGROUND DOCUMENTS 54

APPENDIX C. SUMMARY OF MEASUREMENT TECHNIQUES THAT HAVE BEEN USED TO

CHARACTERIZE SURFACES 62

APPENDIX D. LIST OF RECENT PUBLICATIONS ON SURFACE-RELATED MEASUREMENTS BY STAFF OF THE INSTITUTE FOR BASIC STANDARDS 64

REFERENCES 69

LIST OF FIGURES

Figure 2.1 Number of papers published per year in x-ray photoelectron

spectroscopy (XPS), Auger-electron spectroscopy (AES), and

combined AES and low-energy electron diffraction (LEED) from

recent bibliographies 10

Figure 2.2 Input-output direct measurements transactions matrix for the

measurement of surface properties. 21

Figure 4.1 Programmatic trends from the Electron Physics Section in 1955

to the Surface and Electron Physics Section of 1975 together

with the corresponding number of full-time, permanent, professional employees. "El. Opt." denotes electron optics,

"El. Pol." denotes electron polarization, and "El. Scat."

denotes electron scattering in solids 39

Figure C.l Outline of surface-characterization techniques 63

LIST OF TABLES

Table 2.1 Outline of surface measurement techniques discussed in this report. An asterisk denotes a technique for which instrumentation is manufactured

in the U.S. while a dagger denotes a technique for which instrumentation is marketed in the U.S. from foreign sources 8

Table 2.2 Present (X) and former (F) manufacturers of surface-measurement

equipment based on the techniques listed in Table 2.1 11

Table 2.3 Estimated number, individual average cost, and total

capital investment in commercial LEED, AES, XPS, and

ISS/SIMS instrumentation (worldwide) 12

Table 2.4 Major suppliers of instrumentation, measurement techniques, measurement methodology, reference data, measurement concepts, and analtyical

services for the measurement of surface properties. Column 1 indicates

the major categories of suppliers, column 2 shows examples or components

of the categories to define their scope, and column 3 indicates the

type of measurement service provided (A = reference data, B = measurement concepts, C = instrumentation and measurement techniques, D = mea- surement methodology, E - analytical services). The first column shows

the appropriate standard industrial classification (SIC) codes from

1972 manual 20

i i
Table 3.1 Applications of Auger-electron spectroscopy (AES) and x-ray

photoel ectron spectroscopy (XPS) in twelve government laboratories. . 24

Table 3.2 Applications of Auger-electron spectroscopy (AES) and x-ray

photoel ectron spectroscopy (XPS) in six chemical -i ndustry

laboratories 25

Table 3.3 Applications of Auger-electron spectroscopy (AES) and x-ray

photoel ectron spectroscopy (XPS) in seven petrol eum- i ndustry

laboratories 26

Table 3.4 Applications of Auger-electron spectroscopy (AES) and x-ray

photoelectron spectroscopy (XPS) in nine metal 1 urgical -industry

laboratories 27

Table 3.5 Miscellaneous industrial applications of Auger-electron

spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) in ten laboratories of manufacturing industries 28

Table 3.6 Impact areas of applied research and engineering that involve

surface properties, processes or measurements, selected from

the recent National Academy of Sciences report "Materials and

Man's Needs" [145] 31

Table 4.1 Major surface-related accomplishments of the Surface Physics

Program from 1969 to 1974 and the nature of their impact 41

Table C.l Key to acronyms shown in figure C.l 62

1 i i

OPTICAL PHYSICS DIVISION SUMMARY REPORT

on a study of

THE NATIONAL MEASUREMENT SYSTEM FOR SURFACE PROPERTIES

C. J. Powell

Optical Physics Division

Institute for Basic Standards

EXECUTIVE SUMMARY

The large number of solid-surface

properties that can be measured have been

arbitrarily divided into two classes.

First, there are the properties which can be

used to characterize a surface: surface

composition (as a function of position),

surface atomic structure, surface electronic

structure, the nature and distribution of

surface defects, surface topography, and the

nature and area of exposed facets. Second,

there are derived properties of the surface

characteristics as just defined and measures

of the processes that occur on surfaces:

electrical properties, optical properties,

adhesion, bonding, catalytic activity,

plating, durability, corrosion, decoration,

grain-boundary segregation, lubrication, and

reactivity. This report discusses directly

only those measurements that are used for

surface characterization with particular

emphasis being given to the most common measurement, the measurement of surface

composition, and lesser emphasis to the

measurement of surface atomic structure and

surface electronic structure. Measurement

of surface topography is discussed in a separate report of this series by R. D. Young

Throughout the report, the term "surface"

is defined as the "outermost" layer of atoms

of a solid. Thus, consideration is given

primarily to those properties (and measurement methods) which are specific to the

surface as defined. Some consideration is given also to the measurement of composition

as a function of depth from a surface and at solid-solid interfaces.

A dramatic feature of this part of the

National Measurement System is the rapid

growth of surface science and surface technology and the substantial accomplishments

that have been made in the past ten years.

Surface science and surface technology are widely regarded as "frontier" areas in which

major scientific breakthroughs will occur

and major improvements in materials and

processes will be developed.

Most of the measurement methods now in use for surface characterization have become

commercially available within the past ten years. At this time there is a complete

lack of standards, standard procedures, and

standard materials to support surfacecharacterization measurements. In short,

there is no established measurement system

for the measurement of surface properties.

Most measurements of surface composition

are now performed by Auger-electron spectroscopy and, to a lesser extent, by x-ray

photoelectron spectroscopy, ion-scattering

spectroscopy and secondary-ion mass spectroscopy. The sales of these instruments

have been estimated to be about $10M per

year with a current growth rate of 20 to 30%

per year. About 60% of these instruments

are in use in industrial laboratories, 20%

in Federal Government laboratories, and 20%

in university laboratories.

The surface-characterization measurements

made in university and some other laboratories are frequently made to develop a fundamental understanding of the properties of

relatively ideal (i.e., single-crystal)

surfaces and of processes that occur on them. Surface-characterization measurements

made in government laboratories support a variety of agency missions, ranging from

national defense, space, energy, to the

envi ronment

Measurements of surface composition are routinely made to solve an extremely wide

range of industrial problems (of which

examples are given). Most of these measurements are made in the semiconductor, chemical, petroleum, and metallurgical industries

for applications ranging from process and

device development, process control, process

evaluation, to failure analysis. The economic benefits are difficult to estimate but

are believed to be substantially greater

than the corresponding costs. Continued substantial growth in surface

science and surface technology (and in the

required surface-measurement capability) is
predicted for the the next five years.

Present national goals for solution of the

energy crisis, provision of an adequate

defense capability, control of environmental

pollution, increase of industrial productivity, and the development of advanced

materials for improved individual health and

safety and for the automobile and aircraft

industries will require use of surface

technology and improved surface-characterization measurements. Other factors which

will stimulate growth in surface-measurement

capability are projected developments in

surface science, development of improved

instrumentation, development of quantitative

methods for surface characterization, legal

needs, and anticipated growth in the applications of surface analysis.

Present surface-characterization mea- surements make use of reference data generated by instrument manufacturers, universities, government and industrial laboratories, and by NBS. Many important measurement needs have been identified, the most

important, for surface technology, being to provide data and procedures to quantify

measurements of surface composition. It is anticipated that the development of standards, standard procedures, reference data,

and standard materials will be coordinated

through the recently formed ASTM Committee

E-42 on Surface Analysis.

Other measurement needs in surface sci- ence and surface technology have been identified. Many surface properties and pro- cesses depend on the surface composition,

atomic structure, and particularly the

surface electronic structure. It is anticipated that future developments in surface

science will lead to a more detailed understanding of the mechanisms of catalysis,

corrosion, adhesion, lubrication, and wear

so that new materials with improved properties can be designed. Advances of this type

depend on the development and application of new measurement methods to characterize

disordered surfaces, highly dispersed catalysts, transient species on surfaces, the

kinetics of reacting species, and the properties of such surfaces in their working

environments.

NBS programs in surface physics have had

considerable impact on surface science

through the development of new instruments

and measurement methods, the observation of new surface properties, the development of

new theories and concepts, the provision of

reference data, and the publication of data

compilations and critical reviews. NBS data

are also being used in surface technology.

Additional NBS effort is required, however,

to promote surface technology.

Seven recommendations are given for NBS

action to improve and extend the measurement

services required for the support of surface

science and surface technology. Meaningful

action by NBS and other interested groups

should enable the establishment of a satisfactory National System for the Measurement

of Surface Properties in the future.
1. INTRODUCTION

Surface properties are not only an integral part of our present culture ("beauty is only skin deep") but impact considerably on the properties of materials and the

development of new technologies important

for our industrial society. Processes and

properties such as catalysis, adhesion,

lubrication, durability, bonding, oxidation,

passivation, plating, epitaxy, coating,

doping, and crystal growth depend critically

for their success or failure on surface

characteristics. Likewise, the minimization

of material or device failure (i.e., product

reliability) can depend on the reduction of

corrosion or wear, the absence of surface

contaminants in the fabrication of semiconductor devices, or the nonoccurrence of

embrittlement in metals caused by segregation of impurities to interfaces.

The history of surface science and sur- face technology in this century is inter- woven with discoveries and developments in

other branches of science and technology:

the discovery of thermionic-, photo-, field-,

and secondary-electron emission; the

development of radio, x-ray, and special

purpose tubes; the discovery of electron

diffraction; the developments of electron

optics and electron-optical instrumentation;

the investigations of the interactions of

electrons, ions, neutral atoms and molecules,

and photons with matter; the development of vacuum science and technology; the investigations of discharges in gases; the development of lamps; the development of semiconductor devices; the investigations of

factors affecting the joining, working,

wear, and polishing of metals; the investigations of corrosion and oxidation processes

and the development of protective coatings;

the studies of the adsorption, desorption,

and reactions of gases on surfaces; and the

development and characterization of improved

catalysts. Many significant developments in surface science and surface technology,

however, have occurred within the last ten years. We will show in this report that

surface science has reached a stage of

development such that knowledge of fundamental surface parameters can now be obtained. This growth has enabled the development of a new class of surface instrumentation that has been successfully applied to failure analysis, quality control, process

evaluation and process development in the

electronics, chemical, petroleum, and metallurgical industries. New national needs

and the demand for improved materials and

for new technologies have led to increasing

demand for improved and more sensitive

methods for characterizing surfaces and for

measuring surface properties.

Throughout this report we will be discussing only the surfaces of solids; the

properties of liquid surfaces, and solid/

liquid interfaces, however, are of considerable importance in chemical technology and

in biology. The term "surface" implies that

there is a region in a given material where

the properties are distinctly different from

those of the "bulk." Likewise, the availability of scientific techniques and com- mercial instrumentation for the measurement

of surface characteristics implies a particular depth sensitivity for the technique

or instrument. For most of this report we

will consider the ultimate definition of a surface, namely the outermost layer of atoms

of the solid. We will use the term "surface

region" to describe a region near the surface of less than ten atomic layers thickness. We therefore do not intend to discuss

measurement techniques or properties that do not depend on or are not sensitive to the

surface or surface region as just described.

Measurements of surface finish and topography are discussed in a separate report of

this series by R. D. Young.

A realization of the current importance

and relevance of surface science and technology can be obtained from two comprehensive surveys concerning future directions

in physics and opportunities in materials

research conducted recently under the

sponsorship of the National Academy of

Sciences [1,2]. In "Physics in Perspective"

an expert panel on physics of condensed

matter has listed a number of topics of high

current interest in that they are the con- cern of a large number of physicists and

they represent areas in which major scientific breakthroughs appear likely. Surface

physics was one such topic. We quote from

this source [1]:

"Rapid advances are taking place in the

characterization of the surfaces of

solids, largely using new experimental

techniques and the improved theoretical

understanding of quantum mechanics as applied to interfaces. By characterization is meant a detailed specification of

the chemical identity, geometrical position, and, ultimately, the electronic and

vibronic structure of atoms at surfaces.

The electronic, geometrical, and chemical

behavior of defects and impurities adsorbed at the surface is another aspect

of this problem. Also included in this

category are the phenomena of tunneling

in metal -insulator-metal , metal -insul a- tor-semiconductor, and metal -insulator

structures. Because of new experimental

3
techniques such as Auger spectroscopy,

advanced electron microscopy, and ultrahigh vacuums, rapid progress is being

made. Entirely new methods for the

control and preparation of interfaces

have emerged from the vast amount of

engineering and development carried out

in recent years to produce integrated

circuitry and other devices. The present

rate of growth in this area offers the

possibility of advanced understanding and

control of chemisorption and catalysis."

In "Materials and Man's Needs," a distinguished panel has pointed out that improved materials are needed for major

national goals, such as improved or new methods of energy generation, communication, transportation, health services,

housing, management of the environment,

and consumer goods [2]. The panel describes a number of frontiers in materials research that they believe will lead

to improved materials and processes.

Work on surfaces was one of the designated frontiers, and we quote the opinion

of the panel to show the extensive impact

of surface technology:

"Surfaces and interfaces are possibly one of

the most fruitful research topics in materials science. Knowledge at the most

fundamental level in this area can be

expected to be relevant to almost all uses of materials, from the processing

and performance of integrated circuits to the corrosion of structural components,

from frictional wear and energy loss to catalysis and flammabil ity, from crystal

growth to adhesion. The variety and

complexity of surfaces and surface layers

are at least comparable to the variety

and complexity of bulk properties, but our understanding of surfaces is, in contrast, in its infancy.

"The aim is to develop more sophisticated

insight into the electronic and chemical

properties of surfaces. These properties

are very sensitive to the detailed ways

in which atoms are positioned at the

surface, however, and in general these

positions are not known. Surface properties are related also to the properties

of the underlying bulk material, but in

ways that are not often clear. And

though bulk properties, by-and-large, are understood in principle, if not always in detail, this is not true of many of the

surface properties where the broad outlines of the phenomenology are only now

being drawn. This phenomenology concerns,

for example, the details and statistical

mechanics of surface topology, local bond

and electronic structures, the energy

states of electrons at surfaces, and

models for nucleation and growth.

"Surfaces offer an extra degree of freedom

for the arrangement of atoms statistically on the lattice sites. The statistical mechanics of this situation,

extending in three dimensions over

several atomic layers, needs considerable

development. The roughness of a surface

on the atomic scale has a major impact on adsorption, surface diffusion, and crystal growth, but very little is yet known

about the detailed role of surface roughness in these processes.

"The electronic properties of surfaces in

simple systems warrant considerable

attention. There is some controversy

about the extent to which surfaces can be

treated as an extension of the bulk--that

is, whether the discontinuity in properties at the surface is great enough to require new concepts and analytical

procedures. Our theoretical models for

surface electronic properties, surface

relaxation, and surface structure are rudimentary. The extent to which surface

states on semiconductors are intrinsic to the surface or associated with surface

impurities is under debate. Surface

states occur both at free surfaces and at interfaces, such as the silicon-silicon

oxide interface. It has been shown

recently that various surface states on semiconductors correlate with various

surface structures as revealed by lowenergy electron diffraction.

"Surface nucleation, vapor deposition,

adsorption, and surface contamination,

topics with clear practical significance,

are currently being investigated in

detail for a variety of systems, with

emphasis on the simpler systems. The

kinetic and thermodynamic properties of

vapor deposits can be obtained by mass spectrometric methods, and the distribution of clusters on the surface can be

determined by diffraction methods.

Classical surface nucleation theory is inadequate to account for the results of

such measurements, and major modifications of the theory appear to be necessary. Adsorbed atoms can be identified

by Auger spectroscopy, even at a small

fraction of a monolayer coverage. Auger

spectroscopy coupled with ion bombardment

can be used for profiling, to get at bulk

composition profiles below the surface.

Low-energy electron diffraction is just

entering the stage at which the position

of surface atoms can be determined

quantitatively with some accuracy. These

methods are also being used extensively
to monitor the cleanliness and structure

of surfaces and to investigate production

problems involving contamination at surfaces. The electronic and chemical

properties of surfaces and adsorbed

species are being investigated by a variety of methods. X-ray photoel ectron

spectroscopy and ultraviolet photoemission spectroscopy are used to obtain

band-structure data. Knowledge of electronic and chemical bonding can be

derived from ion neutralization spectroscopy. Infrared reflection spectroscopy

gives information about chemical bonding,

and insights concerning deep electronic

levels can be obtained from the analysis

of Auger spectra.

"The techniques developed for surface re- search, such as ion mass analysis and

Auger spectroscopy, are providing the

best, and often the only, methods for

investigating materials problems associated with thin films, grain boundary

segregation-, interdi f fusion phenomena,

and trace analysis. The trend toward

miniaturization in electronics, resulting

from economic, reliability, and highfrequency considerations, points toward

growing importance of surfaces. The

concepts of miniaturization are best

embodied in the technology of large-scale

integrated circuits, where surface and

grain-boundary diffusion often dominate

bulk diffusion processes. This trend is expected to continue, particularly as optical microcircuitry is developed.

"The elucidation of catalytic processes is not detailed in most cases. Considerable

qualitative insight is available, but the

roles of surface structure, surface

defects, surface geometry, surface electronic properties, and even the bulk

properties of catalysts have not been

clarified in detail

"Notable advances have been made in the area

of adhesion, where knowledge of the role

of adlayers and their interaction has

contributed significantly. Friction is

understood in some detail, especially the

role and interaction of the asperities in

sliding contact, but the processs is difficult to treat from a fundamental

standpoint, let alone circumvent in

practice. From a practical point of

view, the lubrication of sliding contacts

is fairly well understood, but cold

welding can be a serious problem in

electrical contacts. Erosion, corrosion,

and contamination of electrical contacts

as a result of arcing remain serious

problems.

"Deeper knowledge of the behavior of sur- faces can also be expected to improve our

control over the important practical

problem of corrosion--the interaction of

a metal with its environment. The pres- ence of water or an electrolyte solution

changes the physics and chemistry of

metal surfaces significantly. The sur- face energy is altered and becomes a strong function of the charge in the

electrical double layer at the metal/

solution interface. The equilibrium

surface structure may be different from

that in the presence of the metal's own vapor or in a vacuum, and it presents

extra problems because the interface is not readily examined in situ. Some

metals, such as silver, undergo surface

rearrangement in aqueous solution at room temperature. Alloys generally undergo a change in their equilibrium or steadystate surface composition. The atomistics of these phenomena are poorly defined. There is much ignorance regarding

the effects of surface stress, defect

structure, and nonequi 1 ibrium conditions

on the reactivity of metal surfaces, and

these effects are of major importance in

the performance of materials."

The latter report clearly shows the

diverse and pervasive role of surfaces in

current technology. Claims have been made

over the last thirty years, however, that

"surface science" or a particular, then new, technique would "solve" major problems or

lead to dramatic improvements in major areas

of surface technology such as catalysis and

corrosion. Although some of these claims

have been overoptimi stic , the optimism of

the above two National Academy of Sciences

reports is warranted by the following significant developments in the last decade:

(a) The routine attainment of ultrahigh

vacuum;

(b) The development of techniques to prepare and characterize surfaces;

(c) The extension of solid-state theory

to surfaces;

(d) Mushrooming developments in surface

science;

(e) The development of commercial instrumentation that can be used to measure sur- face structure and composition;

(f) The development of surface-related

technologies (microelectronics, catalysis,

control 1 ed-thermonucl ear- fusion reactors

,

corrosion) in response to material needs or problems (energy, pollution, defense,

materials conservation, and productivity);

and

5
(g) The successful use of surface

instrumentation (e) to solve important

surface-related problems (f).

Advances in surface science and technology depend on the availability and quality of

measurements of relevant surface characteristics. We describe in this report the

status of measurements now being made in

surface science and surface technology and

show the improvements in measurement capability that are needed. Most of the information for this report was collected and

most of the writing was done in the spring

of 1975. Some revisions and additions have

been made in the summer of 1976 in response

to recent developments.

2. STRUCTURE OF THE MEASUREMENT SYSTEM

2.1 Conceptual System

The conceptual base of modern surface

measurements rests on conventions rather

than on formal definitions adopted by statutory bodies. These conventions are rather

general but have nevertheless been found

useful by workers in the field. As will be

pointed out in section 2.2, it appears

likely that a more specific base will be

established in the not too distant future

for some surface measurements.

It is useful to consider the properties

and characterizations of "ideal" and "real"

surfaces. "Ideal" surfaces are those that

are believed to have relatively simple

structure and composition whereas "real"

surfaces are those that are encountered in

practice. Real surfaces can range from

those prepared to approximate ideal surfaces

as closely as possible (so that measured

properties can be compared realistically

with the results of calculations which are usually made for ideal surfaces) to those

generated, for example, in a manufacturing

process or those resulting from the failure

of a component.

We can distinguish three types of ideal

surfaces

(a) A surface consisting entirely of a plane, single-crystal face of a material.

It is implicitly assumed that the size of

the exposed plane is large enough so "edge

effects" do not affect the measurement being

made; the minimum plane size may thus be a function of the measurement technique being

used.

(b) A single-crystal surface as in (a)

uniformly covered partially or wholly with

known amounts of foreign atoms. The coverage of adatoms can vary typically from

1/1000 of a monolayer to several monolayers

in the range of present interest.

(c) An interface consisting of two crystals with adjoining surfaces as defined

in (a). The thickness of the crystals can

be small (several monolayers, as in (b)) or

large.

To adequately characterize a surface, it

is often necessary to measure the following

quantities [3]:

(1) The type of atomic species present

on the surface;

(2) The arrangement or structure of the

surface atoms;

(3) The electi^onic structure (principally of the valence electrons) of the surface

atoms; and

(4) The motion of the atoms (atomic

vibrations, surface diffusion, diffusion to and from the bulk, and evaporation).

These quantities are interrelated in the sense that a surface, like other physical

systems, will relax after generation toward

a configuration of minimum total energy.

For example, a surface generated by a perfect cleave of a single crystal can relax by

(i) modification of the atomic species on the surface (if the solid contains more than

one atomic component), (ii) modification of

the surface atomic structure with, in each

case, (iii) resulting modifications of

electronic structure and atomic dynamics.

We can also consider three types of real

surfaces

(A) Polycrystal 1 ine surfaces, with

varying areas of single-crystal faces (facets) exposed and with varying amounts of

defects (steps, pits, dislocations,

scratches, etc.). The surfaces may vary in

size from those of small particles (e.g.,

particulates or dispersed catalysts) to those of particular products or devices

(e.g., integrated circuits, mirrors or weldments)

(B) Surfaces such as those described in

(A) covered partially or wholly with foreign

atoms to varying degrees of uniformity.

(C) Interfaces formed at the junction of

two solid phases where the junction region

can extend over a distance much larger than

atomic dimensions.

Such surfaces generally need to be characterized by measurement of the quantities

specified in items (1) through (4) above

together with measurements of:

(5) The nature and distribution of

defects on the surface;

(6) The surface topography;

(7) The nature and area of exposed

facets

(8) The spatial distribution of foreign

atoms on the surface; and

6
(9) The depth distribution of different

atomic species in the vicinity of interfaces . "Complete" characterization of a surface

on the scale indicated above is rarely

attempted on account of the cost and com- plexity involved, the belief that certain

types of characterization may not be re- quired for a particular application, or the

dynamic nature of surfaces. This last

factor is extremely important; a surface can change its structure and composition as a function of time, either after generation,

after heat treatment, after or during a particular surface-characterization measurement, or, more subtly, as the result of

probe-sample interactions during what was intended to be solely a surface-characterization measurement.

We have outlined above the many ways in

which a surface can be characterized.

Measurements on surfaces, however, are made

for a variety of purposes ranging from

scientific to technological. For scientific

applications, a surface will often have to be characterized fairly completely to test a theory or to gain a fundamental understanding of a particular property or process.

For technological applications, the surface

will generally have to be characterized to the extent necessary to relate to a particular phenomenon or the measurement of other

surface-related properties. Such properties

include:

(i) electrical properties (e.g., of

integrated circuits);

(ii) optical properties (e.g., re- flectance of mirrors);

(iii) adhesion

(iv) bonding

(v) catalytic activity

(vi) plating

(vii) durability

(viii) corrosion

(ix) decoration

(x) grain-boundary segregation

(xi) lubrication

(xii) surface reactions (e.g., fuel

cells)

(xiii) biocompatibi 1 ity

It is beyond the scope of this report to describe the nature and status of measurements of all surface-related properties,

particularly as this is a relatively new and

fast-growing area of activity. The discussion will instead be devoted predominantly

to the surface characterizations that are commonly and can routinely be made with

commercially available instrumentation,

namely items (1), (2), (3), (8) and (9)

above. (Measurement of surface topography

is described in a separate report in this

series.) Particular attention will be

devoted to measurements currently required

to advance surface science and to those

required to advance surface technology. In the latter category, measurement of surface

composition (items 1, 8 and 9 above) will be

discussed at some length as it impacts

directly on many other surface-related

properties (items (i) through (xiii) above).

2.2 Basic Technical Infrastructure

2.2.1 Documentary Specification System

As noted in section 2.1 above, no formal

standards or documentary specifications now exist for the characterization of surfaces,

as defined earlier. This situation, how- ever, is expected to change in the near future

In March 1974, ASTM Subcommittee E-2.02

on Surface Analysis was formed. Four task

groups have been formed (Auger-electron

spectroscopy, x-ray photoelectron spectroscopy or ESCA, ion-microprobe analysis and

secondary-ion mass spectroscopy, and ionscattering spectroscopy) and it is anticipated that they will develop consensus

standards for nomenclature, procedures, and

reference materials for their respective

techniques of surface analysis. In May

1976, this subcommittee was converted to a full committee (ASTM Committee E-42 on Surface Analysis) and the above-mentioned

task groups were converted to subcommittees.

ASTM Committee D-32 on Catalysts was formed

in January 1975 to promote, inter alia, the

development of test methods (such as surface

chemical analysis) and materials pertaining

to catalysts. In addition, a commission of

the International Union of Pure and Applied

Chemistry is drafting proposals for standardized nomenclature and data presentation

for electron-spectroscopic methods of mea- surement in physical -chemistry experiments.

2.2.2 Instrumentation System

2.2.2.1 Measurement Tools and Techniques

A large variety of measurement techniques

has been proposed for the characterization

of surfaces. A summary of these techniques,

adapted from a recent review of surface

physics by Murday [4], is given in Appendix

C while assessments of the scientific and

technological utility of many of the techniques are given in a number of recent books

and articles [3-53]. Many of these techniques are relatively new and/or undeveloped

and, although they may give useful information concerning a surface, the

7
interpretation of the data may be complex

or the technique may be restricted to special classes of materials. We will

therefore restrict attention here to the more important techniques that are in widespread or growing use and, in the case of

measurements in surface technology, to those

for which appropriate instrumentation is commercially available. We should note,

however, that the less-common techniques

employed in surface-science experiments

frequently make use of commercially available components. Also, new developments in surface science and improvements in instrumentation and techniques initially developed

for applications in surface science usually

precede further development by instrument

manufacturers and others for ultimate application in surface technology.

We will discuss in this report the

following types of surface-measurements.

(1) Measurement of Surface Composition

(a) Auger-electron spectroscopy

(AES)

(b) X-ray photoel ectron spectroscopy (XPS)

(c) Ion- scattering spectroscopy

(ISS)

(d) Secondary-ion mass spectroscopy

(SIMS), including ion-microprobe mass analysis (IMMA) and

secondary-ion imaging mass spectroscopy (SUMS)

(e) Appearance-potential spectroscopy (APS)

(f) Field-ion microscope - Atomprobe spectroscopy (FIM-APS)

(g) Fiel d-desorption spectroscopy

(FDS)

(h) Internal -reflectance spectroscopy (IRS)

(i) Inelastic electron tunneling

spectroscopy (lETS)

(j) Rutherford backscattering

spectroscopy (RBS) We will discuss the means by which spatial

variation of composition across a surface

can be obtained and how the depth-variation

of composition can be measured.

(2) Measurement of Surface Atomic

Structure

(a) Low-energy electron diffraction

(LEED)

(b) Field-ion microscopy (FIM)

(c) Field-desorption spectroscopy

(FDS)

(d) uv photoelectron spectroscopy

(UPS)

(e) Electron-stimulated desorption

of ions (ESDI)

(f) Auger-electron spectroscopy

(AES)

(g) Ion-scattering spectroscopy

(ISS)

(h) Electron energy-loss spectroscopy (EELS)

(i) Internal -refl ectance spectroscopy (IRS)

(3) Measurement of Electronic Structure

at Surfaces

(a) X-ray photoelectron spectroscopy (XPS)

(b) uv photoelectron spectroscopy

(UPS)

(c) Auge; -el ectron spectroscopy

(AES)

(d) Electron energy-loss spectroscopy (EELS)

(e) Field-electron energy spectroscopy (FEES)

(f) Ion-neutralization spectroscopy

(INS)

(g) Appearance-potential spectroscopy (APS)

There are additional measurement techniques

(e.g., el 1 ipsometry) that are extremely

useful for monitoring changes of surface

composition or of film thickness but which

will not be discussed here as they cannot be

used to identify the specific elements

present on a sample.

A schematic outline of the techniques

listed above is shown in table 2.1. Here,

Table 2.1 Outline of surface measurement

techniques discussed in this report. An asterisk denotes a technique for which instrumentation is manufactured in the U.S.

while a dagger denotes a technique for which

instrumentation is marketed in the U.S. from

foreign sources.

Detected

\Particle

IncidentN.

Probe Photons Electrons Ions

Photons

Electrons

Ions

Electric

Field

IRS*

APS

XPS*^

UPS^

AES-EE*"'' EELS*^

lETS

LEED*^

INS

FEES

ESDI

ISS*

RBS*

sums!

SIMS*|

imma*^

FIM

8
as with the other surface-measurement techniques, we have an "incident probe" on a sample surface. The incident probe can be

an atom (or molecule), an ion, an electron,

a photon, or an electric or magnetic field.

The experimenter observes a scattered or secondary particle (atom, ion, electron, or photon) that results from the interaction of

the probe with the sample. The variety of

techniques involving incident or detected

electrons listed in table 2.1 is an indication of their importance in surface measurements. The surface sensitivity of many of

these techniques is in fact due to the very

large interaction cross sections for lowenergy electrons in solids. We finally note

that Auger-electron measurements can be

performed either with electron excitation

(AES-EE) or with x-ray excitation (AES-XE).

Particular attention will be devoted in

this report to item 1 above since measurements for the determination of surface

compositions are of considerable importance

now in surface science and technology.

Measurements of surface atomic structure and

of surface electronic structure are of

considerable importance in surface science

on account of their anticipated impact in

surface technology (e.g., by understanding

and controlling mechanisms of catalysis,

bonding, and corrosion and through development of improved semiconductor thin-film or electrochemical devices).

It should be emphasized that most of the

techniques listed in table 2.1 are relatively

new or currently undergoing rapid development in scope, techniques, or accuracy of

measurement. (Use of the word "new" in this

context implies a time of less than ten years since the technique was proposed or demonstrated scientifically.) To illustrate

this point, figure 2.1 shows the number of

papers published per year in x-ray photoelectron spectroscopy (XPS), Auger-electron

spectroscopy (AES), and combined AES and

low-energy electron diffraction (LEED) for

years where this information is available in

bibliographic form [54-56]. Although LEED was discovered by Davisson and Germer in

1927, it has not been used or applied ex- tensively except during the past ten years.

In fact, it has only become possible in the

last several years for the surface structures and lattice constants of clean singlecrystal surfaces to be obtained routinely

from LEED data with reasonable accuracy, and

it is only in the last two years that sur- face structures, bond sites and bond lengths

have been similarly deduced for adsorbates

on single-crystal surfaces. Likewise,

figure 2.1 shows the tremendous growth in

XPS and AES that has occurred in the last

five to seven years. Inspection of the

subject indexes of journals which publish

articles on surface science and technology

shows that there has been substantial growth

in the use of all surface-characterization

methods over the last four years; a recent

bibliography on AES shows that there were

about 500 papers on this subject published

in 1975 [55(b)].

At this time, there are no formal standards or procedures for the operation and

calibration of surface instrumentation

(specifically for the techniques shown in

table 2.1) or for the analysis of measurement data. Each experimenter is expected to do the best he can based on his own training

and experience and using the sometimes

conflicting data, spectra, and analytical

procedures

2.2.2.2 The Instrumentation Industry

Complete instruments or components for

the measurement techniques listed in table

2.1 can be purchased from the manufacturers

shown in table 2.2. We show here present

and former manufacturers of this equipment

listed alphabetically according to whether

the equipment is made in the U.S. or whether

it is made elsewhere and marketed in the

U.S. The information for this table was obtained from recent exhibits of surfacemeasurement equipment (Joint Meeting of the

Electron Microscopy Society of America and

the Microbeam Analysis Society, Las Vegas,

August 1975; American Vacuum Society,

Philadelphia, October 1975; and the

Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, March 1976),

listings in recent directories of scientific

instrumentation [57-59] and a recent survey

article [17].

Based on an awareness of published

literature, contacts with many of the manufacturers listed in table 2.2, a recent

analysis [60] of the analytical -instruments

market, and a survey of instruments on exhibition at the 1976 Pittsburgh Conference

[61], we have identified AES, IMMA, ISS,

LEED, SIMS, and XPS as the surface-measurements techniques with the greatest number of

U.S. users. Most domestic manufacturers of

these types of equipment were requested in

early 1975 to provide information concerning

their instrument sales and their purchasers.

Information on sales was solicited in an attempt to determine the size of the instrument market, the extent to which these

instruments are deployed, and the economic

significance of these surface measurements

in this part of the National Measurement

System. Information concerning identity of

9
250

1962 1964 1966 1968

YEAR

1970 1972

Figure 2.1 Number of papers published per year in x-ray photoelectron spectroscopy (XPS),

Auger-electron spectroscopy (AES), and combined AES and low-energy electron diffraction

(LEED) from recent bibliographies.

IQ
Table 2.2. Present (X) and former (F) manufacturers of surface-measurement equipment based

on the techniques listed in table 2.1.

Manufacturer

Measurement lechnique

rtni-tt lELS IRS

T ISS LEED RBS SIMS UPS XPS

(a) U.S. Manufacturers

Advanced Metals Research

Applied Research Laboratories

Coates and Welter

Commonwealth Scientific

Dupont

Etec

Extranuclear Laboratories

GCA/McPherson

General lonex

Harrick Scientific

Hewlett-Packard

Nucl ide

Physical Electronics

3M

Varian

Wilks Scientific

(b) Foreign Manufacturers

AEI (U.K.)

Balzers (Lichtenstein)

Cameca (France)

Hitachi (Japan)

JEOL (Japan)

Leybold-Heraeus (Germany)

Riber (France)

VG Scientific (U.K.)

11
customers or classes of customers was sought

to determine the extent to which these instruments are being used in surface science

and technology (in either government, aca- demic, or various types of industrial laboratories) and, through personal contact of

selected customers, the nature of the use to which the instrument has been put. A report

on the results of the latter inquiries is

given in section 3. Sales information is understandably

regarded as proprietary information but most

manufacturers approached were cooperative in

providing confidential customer lists or informal estimates of their instrument sales

and either the identity of representative

purchasers or information concerning the

distribution of customers in different

groups. The former information is summarized

in table 2.3. A number of comments should be made about

the information contained in table 2.3.

First, the estimate of total numbers of

instruments is based on sales and estimates

provided almost entirely by the U.S. manufacturers; no similar inquiries were made of

foreign companies. The numbers of instruments shown thus reflects sales of U.S.

instruments within the U.S. and abroad and a very coarse estimate of sales by foreign

companies in countries other than the U.S.

Second, the total number of instruments for

each measurement technique cannot be simply

intercompared without consideration of the

time when the technique became "popular"

(cf . , fig. 2.1) and of the related time when

commercial instrumentation became available

from different companies. Third, the estimate of average cost per installation is of

necessity rather crude. The cost of XPS

instrumentation, for example, can vary

widely depending on the manufacturer and the

number of "options" selected by the purchaser.

In addition, LEED optics or a highperformance AES analyzer can be purchased

as components (with or without the related

commercial control and recording electronics)

to be installed on an existing vacuum system.

Fourth, it is difficult to verify the information concerning gross sales that was supplied by a few manufacturers. Nevertheless, the approximate total capital investment in AES, ISS, LEED, SIMS, and XPS equipment of about $50M shown in table 2.3 is

consistent with the independent findings of

Frost and Sullivan, Inc. in a recent analysis [60].

Approximately half to three-quarters of

the instrumentation summarized in table 2.3

has been sold to purchasers in the U.S.

Of this fraction, it is estimated that about

60% of the instrumentation is in industrial

laboratories, about 20% in Federal government

laboratories, and about 20% in university

laboratories. The total U.S. capital investment in this instrumentation is believed

to be greater than $40M. Contacts with

manufacturers and surveys of users and potential users by Researoh/Development magazine (the respondents were predominantly

chemists and analytical chemists) indicate

that the growth rate in instrument sales is about 20 to 30% per year and that the annual

sales volume of LEED, XPS, AES, and ISS/SIMS

equipment is about $10M per year [62].

2.2.3 Reference Data

As pointed out earlier (cf.. Appendix C),

many techniques are employed for the characterization of surfaces and reliable reference

data is of vital importance in both surface

science and surface technology. Reference

data is understood to mean:

(a) data on observed positions and intensities of spectral features measured for some material by a particular technique;

Table 2.3. Estimated number, individual average cost, and total capital

investment in commercial LEED, AES, XPS, and ISS/SIMS instrumentation

(worldwide)

Measurement

Technique

Estimated Total

Number of Instruments

Approximate

Average Cost of

Instrumentation

Approximate

Total Capital

Investment

LEED 150-200 $50K $8.75M

AES 500-600 $50K $27. 5M

XPS 120-150 $100K $13. 5M

ISS/SIMS 40 $65K $2.6M

IMMA 60 $300K $18M

Total $70M

12
(b) theoretical, experimental, and

analytical data on the "measurement process"

for a particular technique; and

(c) data concerning the fundamentals of

the interactions of the "incident probes"

and "detected particles" (cf., table 2.1)

with samples and surfaces of varying degrees

of crystalline perfection, homogeneity,

stability, and reactivity.

Reference data is frequently generated by

workers in surface science and disseminated

in the form of publications in appropriate

professional journals. Summaries of such

data appear from time to time as reviews or

as books (for example, refs. [3] to [53]. Due to the embryonic nature of surface

science and technology, there is at present

a serious lack of adequate reference data,

particularly for the more widely used sur- face-measurement techniques shown in table

2.1. Users of AES equipment, for example,

in the chemical, petroleum, metallurgical,

and semiconductor industries as well as in

government and university laboratories need

reliable reference data to enable them to identify surface contaminants or to determine the composition of a surface following

a particular process. In addition, they

need to have a methodology to convert observed intensities to sample composition and

to have appropriate sputtering data if

composition-versus-depth information is required. Users of this type need reference

data in order that they can solve surface

problems important to the company or industry as readily as possible. Without this

information, the work is impeded or decisions

are made from inadequate or unreliable data.

2.2.4 Reference Materials

No reference materials are produced at this time for applications in surface science

and technology. The need for such materials

has been strongly expressed, however, by

ASTM Committees E-42 and D-32 and by many

individuals contacted in connection with

this study.

Two types of reference materials are needed for applications that require surface

analyses. First, there is the need for pure

materials to calibrate the energy and intensity scales of electron spectrometers (for

AES and XPS) and the intensity scale of mass spectrometers (for ISS, IMMA, and SIMS).

Second, standard materials are needed for

the determination of relative surface composition (to obtain the stoichiometry) or the

absolute surface composition (to obtain

surface density of atoms) in many different

types of systems (alloys, impurities on or near a surface, or a thin film on a substrate)

for a wide variety of applications in the

metallurgical, semiconductor, chemical, and

catalyst industries. Such reference materials would be used to establish calibration

curves to obtain compositions from observed

intensities, to establish sensitivity limits

for the presence or absence of key atoms or contaminants on surfaces, or to obtain performance data on "depth profiling" (the determination of composition versus depth from

a surface by the process of sputtering).

Careful measurements are required for

both types of reference materials to establish their properties (e.g., electron energies and relative intensities) with the

desired accuracy. Also, it is necessary to ensure that the surface of a reference

material can be cleaned or regenerated in a particular instrument.

It is expected that reference materials

will also be used in "round robins" to intercompare measurements made in different

laboratories by the same measurement technique or by different measurement techniques

These intercomparisons and the related

reference data will eventually form the

basis for a satisfactory measurements assurance program for the analysis of surfaces.

2.2.5 Science and People

Surface science and technology are, interdisciplinary activities presently involving

physicists, chemists, and metallurgists.

This diversity of involvement can be appreciated by the many professional societies or organizations that support publications or sponsor meetings in which surface properties

figure prominently. These societies or organizations include (in the U.S.):

(1) American Physical Society

(2) American Vacuum Society

(3) American Chemical Society

(4) Physical Electronics Conference

(5) Electrochemical Society

(6) Microbeam Analysis Society

(7) The Metallurgical Society

(8) Pittsburgh Conference on Analytical

Chemistry and Applied Spectroscopy

(9) Federation of Analytical Chemistry

and Spectroscopy Societies

(10) American Society for Testing and

Material

(11) Gordon Conferences

(12) Electron Microscopy Society of

America

(13) Scanning Electron Microscope

Symposium.

Analogous professional societies and organizations are active in other countries.

13
The scientists working on the frontiers

of surface science typically have the Ph.D.

degree. Although of necessity they have re- ceived training in a particular area of a particular discipline (e.g., physics), many

have had to become proficient in the language and the body of knowledge of related

areas of other disciplines (e.g., chemistry).

There are also many scientists who are con- cerned primarily with measurement of bulk

properties of solids (perhaps using the

surface as a "window" for the solid) who

have of necessity become familiar with

surface processes and problems both to prepare samples of the needed purity and to obtain val id data.

There is a growing number of scientists

and technologists in analytical and other

industrial laboratories who are now routinely using instrumentation (AES, XPS, SIMS/

IMMA, and ISS) to determine surface composition and properties. These people have a diversity of backgrounds with relatively few

having had appreciable previous experience

in surface science or closely related fields.

For example, some of these people would be

familiar with operation of the electronprobe microanalyzer; this instrument, however,

operates at high vacuum rather than at ultrahigh vacuum (as in surface-analysis

instrumentation) and the sampling depth is

typically 10 000 A rather than 10 A. Thus,

because of insufficient familiarity with the new surface-analytical instrumentation and

perhaps because of inadequate training, a buyer may find himself ill-equipped to make

sound purchasing decisions and a user may be

unable to cope with day-to-day subtleties in

specimen preparation and in operation of the

equipment. There is thus a strong and

growing need for short courses and workshops

that will provide up-to-date surveys of the

capabilities of different surface-measurement

techniques and that will help users of particular equipment to operate their instrumentation more effectively. Short courses

of this type have been sponsored over the , last several years by some professional

societies, several universities, and some instrument manufacturers and have been well

attended.

Most of the new developments in surface

science and surface technology appear in

archival journals published by professional

societies and by commercial houses. Information from journals is reviewed, distilled,

and highlighted in a variety of books and

publications ranging from "Reviews of Modern

Physics," "Annual Review of Physical Chemistry," "Analytical Chemistry" (and many

others [3-53]) to "Research/Development" and

"Industrial Research." The large number of

surface-measurement techniques (Appendix C and table 2.1) and the rapid pace of scientific and instrumental developments are

such, however, that there is a continuing

need for up-to-date evaluations of instruments, techniques, and methods of data

analysis for specific types of applications.

Review articles, short courses, and workshops are again required to meet this need.

2.3 Realized Measurement Capabilities

As pointed out in section 2.2.2.1 and in

Appendix C, there are many techniques by

which surfaces are characterized. In addition, there are many properties of solids

(e.g., electrical, optical, reactivity,

bonding, durability) that depend on the

nature and state of the solid surface, as noted in section 2.1. A comprehensive

review and analysis of methods to characterize surfaces and to determine surface properties for the many types of materials and

applications would be voluminous. Since the

status of surface-characterization methods

has been described in recent review articles

and books [3-53] and related techniques have

been described elsewhere [63,64], we will

give a brief assessment of only those forms

of surface characterization that have been

judged to be most significant, namely, items

(1), (2), and (3) listed in section 2.2.2.1.

These will now be discussed in turn.

2.3.1 Measurement of Surface Composition

Several techniques are now used for

qualitative analyses of surfaces. Quantitative analyses of surfaces are not now possible on a routine basis although data for an unknown sample can be compared usefully with

data from a local standard prepared by the user if the composition of the standard

approaches that of the unknown; this method

is not feasible or efficient for many users. Practically all respondents contacted during

this study emphasized the pressing need for

quantitative surface analyses.

The phrase "quantitative surface analysis"

needs to be defined because "analyses" can

be performed in a number of ways depending

on the problem to be solved and on the

sample. Ideally, one might want to know the

composition as a function of position of a mul ticomponent sample. More simply, one might want to be able to say that a certain

amount of a particular element or compound

is present in the surface region of a sample.

For example, one might want to know the

coverage of an adsorbed or condensed atomic

or molecular layer on a surface or to say

that the contamination on a surface is less

14
than some desired amount. In other cases, one might want to measure the composition of

a bicomponent system which could possibly be

homogeneous or inhomogeneous . Finally, it is

frequently desired to determine the concentration of particular elements as a function

of depth from the surface and as a function

of position on or near the surface. Although

one may be able to define the type of analysis that is desired in a particular application, the success in obtaining the desired

analysis depends on the homogeneity of the

sample, the extent to which particular phases

are localized on the surface or in the bulk,

and the sensitivity, specificity, spatial

resolution, and applicability of a particular

analytical method.

The concentration of a particular element

as a function of depth from the surface is now generally obtained through continuous or successive sputtering of the surface, what- ever measurement technique is used to determine the surface composition at a particular

time [7]. Measurements of this type are of

considerable importance in analyzing, for ex- ample, the diffusion of dopants and impurities in thin film and semiconductor devices,

the variation of composition in the vicinity

of grain boundaries, and the differences between surface and bulk compositions of alloy

catalysts. Unfortunately, very little reliable information is now available concerning

sputtering rates, their dependence on ion

species and energy, their variation with

crystalline perfection and orientation, and

their variation with compounding or alloying.

In addition, data need to be obtained on the

extent to which ion bombardment causes dissociation of compounds, stimulates diffusion,

causes lattice damage, or generates ridges,

steps, cones, facets, and protrusions on the

surface [7]. To obtain reliable concen- tration-depth information, one also needs to know the current density and current density

distribution of the ion beam at the sample

and must avoid errors associated with edges

or shadows of the crater formed by sputtering;

the effects of small variations of current

density in the ion beam can be minimized,

however, by scanning the ion beam across the

surface. The depth resolution obtained during sputtering depends on the uniformity of

ion current density, damage to the sample

during sputtering, redeposition of sputtered

material, the sensitivity of the particular

measurement technique for the particular

sample, and the intrinsic sampling depth of

the measurement technique for the particular

material. These and other complicating

factors have been discussed in several recent

articles [65-67].

We will now briefly describe the several

techniques listed in section 2.2.2.1 for the

determination of surface composition and give

a semiquantitative estimate of the measurement capability that has now been attained

for routine conditions of operation. The nu- merical measures given here should not be

construed necessarily as "best" or "limiting"

levels of performance nor should they be used

with the limited information given here to "rate" one technique against another. As Park [5] has clearly pointed out, sensitivity is a function of spatial resolution

and the related flux of "probe" particles,

resolution of the detection system, bandwidth, background level in the vicinity of

the "signal," the noise-power spectrum, and

changes in the sample caused by the incident

probe or by exposure to the residual atmosphere of the vacuum system. That is, the

degree of success or applicability of a particular measurement technique depends

greatly on the details of the measurement

process (i.e., the relevant physics and chemistry) and on the nature of the measurement

or analytical problem. A more extensive

discussion of the analytical performance of

these measurement techniques is given in a recent review by Coburn and Kay [7].

The most common method for determination

of surface composition is Auger-electron

spectroscopy (table 2.3). All elements with

atomic number greater than 2 can be detected

and in most work to date only elemental identifications have been made. The latter situation is attributed to the fact that early

AES measurements were frequently performed

with LEED instrumentation which had relatively poor energy resolution. The resolution of

commercial AES electron energy analyzers has

improved in recent years to the point where

changes in peak positions and in peak shapes

can be observed and correlated with the chemical environment of the particular element.

Identification of chemical compounds by this

technique is at an early stage, but it is anticipated that considerable progress in

this direction will be made in the near

future. The sensitivity of AES in typical

measurement situations can be of the order of

0.1% of an atomic layer [68,69]. The sam- pling depth of AES is usually between 3 and

20 A, depending on the sample, while the

lateral resolution obtained in recently

introduced scanning Auger-electron microscopes can be as low as about 0.1 ym. The

incident electron beam can cause damage

(dissociation, desorption, polymerization,

lattice changes) in some samples but these

effects have yet to be adequately quantified.

15
X-ray-photoelectron spectroscopy (XPS),

also known as ESCA, can be used to detect all

elements although identification of hydrogen

is difficult in most cases. The pioneering

work with this technique was performed at Uppsala University with modified high-resolution 3-ray spectrometers. An important early

result was that relatively small "chemical

shifts" of photolines occurred for an element

in different chemical compounds. Such observations have led to the introduction of x-ray

monochromators of improved performance and to deconvol ution methods to obtain improved

resolution. The sensitivity of XPS measurements is comparable to that of AES [28,70-72]

although surface enrichment techniques have

been used to greatly extend the surface specificity to the ppb level [73,74]. The sam- pling depth in XPS is comparable to that in

AES. Although damage by the incident x-ray

beam has been observed, it seems to be much

less than that found when incident electrons

are used to obtain comparable information.

Auger-electron peaks are also observed in XPS

spectra and can give useful additional information (e.g., by identifying elements for

which the XPS peaks overlap or through larger

observed chemical shifts [75]).

"Matrix effects" can modify intensities

through variations of electron transport in different samples, through variations of

electron backscattering in AES, and through

"shake-up" or "shake-off" effects in both AES

and XPS [7]. The surface sensitivity in both

AES and XPS can be enhanced, if desired, by

collecting electrons emitted at near-grazing

angles to the surface.

Ion-scattering spectroscopy (ISS) with ion

energies less than 10 keV can be used to detect all elements except hydrogen and helium

with a sampling depth of one monolayer, independent of material. The sensitivity is also

about 0.1% of an atomic layer, but the scat- tered-ion yield depends on matrix and neutralization effects and on oscillations in the

scattering cross sections with ion energy

[25,76-78]; these effects are only partly

understood [26,76-79]. Lateral variation of

surface composition can be obtained by scan- ning the ion beam across the sample, at present with a resolution of about 100 ym. Information concerning the sample composition

below the surface can be obtained with incident ion energies much greater than 10 keV

(e.g., helium ions with energies up to 2 MeV), a technique then known as Rutherford

backscattering spectroscopy (RBS) [80].

Complications in analyses can arise on ac- count of channeling in crystalline materials

as well as sensitivity and mass-resolution

limitations caused by multiple scattering and

ion energy loss [77,80].

The secondary ions emitted from surfaces

under ion bombardment can be mass-analyzed to give surface-composition data; this technique

is referred to as secondary-ion mass spectroscopy (SIMS) or, with a narrow (^>> 1 pm)

incident ion beam, as ion microprobe mass analysis (IMMA). Alternatively, the sample

can be bombarded with a relatively broad ion

beam {'^^ 100 ym) and an image of the sample

obtained with secondary ions [i.e., a sec- ondary-ion imaging mass spectrometer (SUMS)]

with a lateral resolution of about 1 pm. All elements can be detected but there are large (many orders of magnitude) variations

in detection efficiency from element to element and large matrix effects [81-84].

The sampling depth and thus the depth of sur- face sputtered is a function of the sensitivity and the beam area; it can vary from about

2 to 100 ^ [81-84].

Appearance-potential spectroscopy (APS) is

a relatively simple technique. Unfortunately,

it can be used to detect only a limited

number of elements for reasons that are not now clear [85]. The sampling depth is usually between 3 and 20 K, depending on the

material, but the sensitivity has recently

been improved to the point where chemisorbed

species on a surface can be detected [86].

Identification of surface atoms can be ac- complished by field- ion microscopy atom-probe

spectroscopy (FIM-APS) [87] and by field-desorption spectroscopy (FDS) [88]. Both techniques represent developments of the fieldion microscope and can be used with a limited

number of solids. In each case, the identity

of the topmost layer of atoms on a specimen

surface is obtained; by successive field

desorption, composition versus depth information can be obtained.

Two measurement techniques that appear to be of growing utility for the determination

of surface composition are internal reflection spectroscopy (IRS) [89-92] and inelastic

electron tunneling spectroscopy (lETS) [93-

96]. The IRS technique can be used to detect

about 4% of a monolayer of chemisorbed gas

(in the favorable case of CO) on a metal

surface [88]. The lETS technique can be used

to detect vibrational excitations of molecules

condensed at a metal -insul ator interface in a metal -insulator-metal junction. Although the

nature of the lETS technique precludes its

application to arbitrary surfaces, it can be

useful in detecting small quantities (e.g., a few percent of a monolayer) of organic molecules deposited on an insulating surface [90-

92].

16
2.3.2 Measurement of Surface Atomic

Structure

While the bulk crystalline structure of

many solids has been determined by x-ray diffraction and electron diffraction measurements, relatively little is known about the

equilibrium arrangement of atoms at surfaces

and the changes that occur with various sur- face treatments.

The technique now in most common use for

the determination of surface atomic structure

is low-energy electron diffraction (LEED)

[50]. Analysis of the data is complex and

only recently have acceptable solutions for

the structures of a number of clean metal

single-crystal surfaces been determined

[9, 11(b), 11 (f), 97]. The structures of or- dered adsorbates on single-crystal surfaces

have also recently been derived, and it is

anticipated that there will be a great deal

of progress in determinations of surface

structures in the next few years [97,98]. A promising possibility is the use of polarized

electrons in diffraction experiments to obtain surface structures [99].

The diffraction patterns observed in con- ventional LEED instruments are due to ordered

regions of sizes up to about 100 A (the typical coherence width of the electron beam).

Steps and other surface imperfections will

modify the electron intensity distributions

[100-103], as well as other surface properties [102-104].

The field- ion microscope (FIM) can be used

to obtain detailed information concerning the

arrangement of surface atoms for a limited

number of solids that^can be shaped with a tip of radius < 1000 A and which can withstand an electric field near the surface of

10 to 50 GV/m [35,87]. The magnitude of the

applied field can be reduced with use of an image intensifier. Information about the

surface structure of particular atomic

species can be obtained with atom-probe

spectroscopy (FIM-APS) [87] or with fielddesorption spectroscopy (FDS) [88].

In the last two years, several measurement

techniques have been proposed for determining

the local atomic structure of clean and

adsorbate-covered surfaces. Although detailed theories of the processes have to be

developed and the range and accuracy of the

techniques have to be demonstrated experimentally, these developments hold the promise

that information concerning the sites and

bond geometries of surface atoms can be

obtained in a fairly direct manner. The LEED technique, on the other hand, is based on coherent electron scattering from ordered

atomic arrays (i.e., long-range order), and

bond geometry information has to be obtained

from a relatively complex analysis of a large amount of data.

It has been shown theoretically that

atomic-structure information can be obtained

from the angular distribution of photoemitted

electrons [105-107]. Several experiments

have been performed that show significant

anisotropics in the photoel ectron angular

distributions for chemisorbed atoms on sur- faces [108,109] and from clean surfaces

[110,111]. These and other similar experiments indicate that data on bonding sites and

directions of surface atoms can be derived

from UPS measurements. Angular anisotropies

have also been observed in the emission of

Auger electrons in AES experiments but it

appears that these anisotropies are not as sensitive to local structure as UPS experiments [112].

Anisotropies have been found in the angular distribution of ions desorbed from adsorbate-covered surfaces under electron

bombardment [113]. These anisotropies in

ESDI experiments are related to the local

bonding of the adsorbate on the surface [114]

and have been compared and contrasted with

corresponding LEED measurements [113].

Atomic-structure information can be obtained from ISS experiments [25,26,115]. Use

here can be made of the fact that a surface

atom (e.g., an adsorbate) has a shadowing

effect with respect to nearby atoms. Alternatively, multiple scattering can be important (usually for higher ion masses, smaller

ion energies, and smaller angles of incidence

and scattering) and give information about

bond distances and geometries.

The vibrations of surface atoms can be

directly measured by IRS [89-92], lETS [93-

96], and EELS [116,117]. The measured en- ergies for the vibrational excitations are related, in part, to the bond geometries and

it appears that the geometries of adsorbates

in different surface binding sites can be

determined.

The technique known as extended x-ray

absorption fine structure (EXAFS) has been

shown to be useful for determining the local

atomic arrangement and atom-atom spacings in

solids and molecules. It now seems likely

that surface sensitivity can be obtained by

measuring the yield of Auger electrons

(emitted following x-ray absorption) as the

x-ray energy is varied [118]. Thus, the

geometries of surface atoms (particularly of

adsorbates on surfaces) could be determined

by this method.

17
2.3.3 Measurement of Electronic Structure

at Surfaces

Many techniques have been used to measure

the electronic structure at surfaces [3,5,

8,10-15,18,31,33,35-50], that is, the spatial

charge distribution and the energy distribution of the electronic states of the surface

atoms. The most common and useful techniques

are: x-ray photoel ectron spectroscopy (XPS)

of valence electrons [1 1 (c) ,12,18,24,40,47,

119]; uv photoelectron spectroscopy (UPS)

[11 (c), 12, 39, 47, 119]; Auger-electron spectroscopy (AES) involving valence electrons

[40,47,50,120]; electron energy-loss spectroscopy (EELS) [5,22,121]; field-electron

energy spectroscopy (FEES) [11(e), 122]; ionneutralization spectroscopy (INS) [13,123];

and appearance-potential spectroscopy (APS)

[5,85,86]. A review of methods for calculating the electronic structure of surfaces

has been published recently [124].

All of these techniques involve electrons

as the incident or detected particles or

both. With the exception of FEES and INS,

the surface sensitivity of the techniques is

due to the short inelastic mean free path

(-v 3 to 20 A) of low-energy electrons (^ 10

to 1000 eV) in solids. With the exception

of FEES, all techniques involve an electronic

transition or excitation. The observed

spectral information is thus related to the

valence electron density of states and to a transition probability appropriate for the

particular process. Additional complexities

can arise, and these can be regarded as making the determination of the density of

states more difficult or as giving additional

useful information about the surface. The

complexity of the measurement process, however, often makes it desirable to compare,

contrast, or combine results obtained by more

than one measurement technique. One technique, FEES, is relatively well understood

[11(e)], but unfortunately it is of less

general applicability than the others.

Despite the complexity in the interpretation of many of the measurements, a large

amount of significant information on surface

electronic structure has been obtained during

the past five years. Surfaces of metals, insulators, alloys, and semiconductors have

been examined. Surface states have been observed on semiconductor surfaces, as expected,

and also on some metal surfaces. Different

electronic structures have been found on different crystal faces of a material and re- lated to the bulk band structure. The pres- ence of single atoms on otherwise clean sur- faces has been detected and their electronic

structure characterized. Different binding

; states of adsorbed atoms and molecules have

been observed with different electronic

structure. The initial stages of oxidation

and corrosion have been detected and an understanding gained of some of the basic

processes. Intermediate species in a prototype catalytic reaction have been observed

and monitored as a function of surface tem- perature. Surface-electronic properties are being related to the symmetry and directionality of surface bonds.

The various measurement techniques for

determining electronic structure at surfaces

have been reviewed recently and extensively

elsewhere [5,8,10-15,18,31 ,33,35-50,120-123].

At this time it is believed that photoelectron spectroscopy (UPS and XPS) has the

greatest utility for determining surface

electronic structure and for relating electronic structure to surface atomic structure.

2.3.4 Summary of Measurement Needs

A large number of measurement methods

(Appendix C) have been developed in the past

ten years, primarily for applications in sur- face science. Many of these measurement

techniques, together with other developments

in experimental and theoretical surface sci- ence and newly developed concepts, are being

increasingly applied in surface technology

(e.g., failure analysis, quality control, and

process development). At this time, however,

there are still needs for new and improved

measurement capabilities in both surface sci- ence and surface technology.

There is a widespread belief that many of

the basic questions concerning surface pro- cesses and phenomena in catalysis, oxidation,

corrosion, adhesion, lubrication, and wear

can now be tackled [125-128]. This belief

and the results that have been obtained to date are no doubt responsible for the tre- mendous recent growth of interest and work in

surface science and technology [1-53]. The

measurement tools now available and that have

just been described have sufficient sensitivity and specificity to be usefully applied

to prototype or model catalysis, corrosion,

and adhesion systems; investigations of this

type are in fact now being successfully

carried out (section 3). Fundamental questions, such as those concerning bonding,

specificity of catalytic reactions, reac- tivity of surfaces, kinetics, reaction paths,

and intermediate species are being tackled.

The measurement techniques now in use need

to be improved so that surface composition

can be specified more exactly as a function

of position, surface structure determined

simply from LEED or other data, and surface

electronic structure determined with greater

reliability than at present. The sensitivity

18
of the surface-composition methods needs to be improved to detect dopants and impurities

in semiconductor devices. Also, new mea- surement methods need to be developed so that catalytic and corrosion reactions can

be studied at higher pressures and on "real"

surfaces. Techniques are required to adequately characterize the small particles

used as catalysts (with diameters of about

20 K) , and other surfaces with large amounts

of disorder and defects. If sufficient

conceptual advances can be made with the

present or improved measurements techniques,

it could be possible, for example, to engi- neer improved catalysts with greater selectivity, efficiency, and longevity for particular reactions. New techniques are also

required to characterize the size and shape

of pollutant particles and the reactions

that occur on them. Special techniques need

to be developed in the continuing quest for

improved materials and processes (e.g.,

semiconductor devices of greater reliability

and surfaces modified by ion implantation to have greater corrosion resistance).

The existing techniques for the determination of surface composition are being

widely applied in surface technology (section

3.1). These techniques need to be further

developed so that quantitative surface

analyses of different types can be made with

known accuracy. Specifically, reference

data (section 2.2.3) concerning materials,

instrumentation and the measurement process,

reference materials (section 2.2.4), and

procedures to make reliable and useful

measurements need to be developed. Specific

needs are itemized in section 4.2.3.1. As new techniques of potential are originated,

it is anticipated that there will be similar

needs for reference data, materials, and

methodology.

2.4 Dissemination and Enforcement Network

2.4.1 Central Standards Laboratories

Programs concerned with certain types of

surface measurements exist at the National

Physical Laboratory in Great Britain, at the

Electrotechnical Laboratory in Japan, and at the National Bureau of Standards. At present,

the organizational infrastructure of this

part of the National Measurement System

(section 2.2) is not well developed; a national dissemination and enforcement

network does not exist in the U.S. nor is there significant international activity in

this area. This situation is expected to change in the near future as a result of the

rapid growth of surface science and technology, the inauguration of ASTM committees on

catalysts and on surface analysis, and as a result of NBS programs dealing with surface

measurements

2.4.2 State and Local Offices of Weights

and Measures

There is no relationship now between NBS

and any state or local office of weights and measures concerning measurement of surface

properties nor is any such relationship an- ticipated in the near future.

2.4.3 Standards and Testing Laboratories

and Services

Many of the manufacturers of surface instrumentation (section 2.2.2.2) offer analytical services that make use of their own instruments. In addition, other companies

offer analyses of surfaces based on x-ray

photoelectron spectroscopy, Auger-electron

spectroscopy, secondary-ion mass spectroscopy, and ion-scattering spectroscopy.

2.4.4 Regulatory Agencies

There are not believed to be any regulatory agencies now concerned with the mea- surement of surface properties.

2.5 Direct Measurements Transactions Matrix

2.5.1 Analysis of Suppliers and Users

Table 2.4 gives a listing of the major

suppliers and users of instrumentation,

measurement techniques, measurement methodology, reference data, measurement concepts

and analytical services for the measurement

of surface properties, as discussed earlier

in this chapter. The first column shows the

major categories of suppliers while the

second column gives examples or components

of the major suppliers to indicate their

scope. These suppliers provide a variety of

measurement services, as indicated in the

third column. It should be emphasized that

the measurement suppliers (and users) do not form a cohesive unit with a well-defined

pattern of activity amongst all members of

the category. That is, individual members

of a category may well supply different

services at different times.

Figure 2.2 is an input-output direct-measurements transactions matrix for the measurement of surface properties. This matrix

shows the nature of the transactions, according to the key at the bottom of the figure,

between suppliers and users of measurement

services in this portion of the National

Measurement System.

19
Table 2.4. Major suppliers of instrumentation, measurement techniques, measurement methodology, reference data, measurement concepts and analytical services for the measurement of

surface properties. Column 1 indicates the major categories of suppliers, column 2 shows

examples or components of the categories to define their scope, and column 3 indicates the

type of measurement service provided (A = reference data, B = measurement concepts, C

= instrumentation and measurement techniques, D = measurement methodology, E = analytical

services). The first column also shows the appropriate standard Industrial Classification (SIC) codes from the 1972 manual.

Suppl ier Lomponen LS Measurement

Service

(1) Knowledge Community

(SIC Codes 2721, 2731

8221, 8621, 8922)

Scientific Organizations

Academic Institutions

Professional Societies

ociciiLiTiL diiu iccnnicai uuurrid i b

A,B,C,D

(2) Documentary Standards

uryaii \ lcxl luiib (SIC Code 8621)

ASTM A,D

(3) Instrumentation Industry

(SIC Codes 3811 and 3823)

Manufacturers of Instruments A,B,C,D

(4) NBS

(SIC Code 9611)

Institute for Basic Standards

Institute for Materials Research

Institute for Applied Technology

A,B,C,D

(5) Testing Laboratories

(SIC Code 7391 and 7397

Instrument Manufacturers

MildiyLICal OciVILc LaL/UfaLUi 1 R and D Laboratories

A,B,C,D,E

(6) Department of Defense

(SIC Code 9711)

e.g., Naval Research Laboratory

Naval Weapons Center

Hava 1 L_icL.Li uii iL.j Lauui a LU i y Air Force (CRL, WPAFB)

Night Vision Laboratory

Picatinny Arsenal

A,B,C,D

(7) Other Federal Government

(SIC Codes 9611 and

9661 )

e.g., tnergy Kesearcn ana ueveiopment Momimstration Contractors (e.g., Sandia Laboratories, Oak Ridge National Laboratory, Argonne

National Laboratory) National Aeronautics and

Space Administration

A R r n

(8) Semiconductor Industry

(SIC Codes 3641, 3661,

3662, 3673, 3674, 3573,

3699)

Manufacturers of semiconductor devices,

computer components, lamps, special vacuum

tubes, communication equipment, office

equipment

A,B,C,D

(9) Chemical Industry

(SIC Codes 2819, 2821,

2823, 2824, 2843, 2891

3861 )

Manufacturers of plastics, films, fibers,

composites, elastomers, adhesives, catalysts,

photographic materials

A,B,C,D

(10) Petroleum Industry

(SIC Code 2911)

Development of catalysts, production of

petroleum products

A,B,C,D

(11) Metallurgical Industry

(SIC Codes 3312, 3353

3411, 3711, 3721, 3724)

Manufacturers of ferrous and nonferrous metal

products

Automobile Manufacturers

Aircraft Manufacturers

A,B,C,D

20
DIkf CT MrflSLiRtMTNTS THa.ssarTIONS *«TRI' rOR

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12 STATF 5 LOCAL

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[e*i-. OiWs & Reo- Aq. ) 13 INDUSTRIAL

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14 AGDICULTURE.rORESTRY

FISHING-. HINI.'IG (SIC Ui». A U)

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(SIC Ofv. C)

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16 F0OD/IO6/TE1CTILE/ APPAREL /LUR/ TURN/PAPER/ LEAIHtk (Sll 20-26, 31

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(SIC 33-34, 391)

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(SIC Rjjor Gp 35) 20 CLICTRIC AND tllCTBONIC CQPMT

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C. Importance

1 = Minor

2 = Moderate

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B. Rate of Change

Declining

Stable

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SUPPLIER

USER

C D

A

B

Atiequacy: Amount of

Improvements Required

0 = None

1 = Minor

2 = Moderate

3 = Large

4 = Major

Magnitude

0 = Trivial

1 = Minor

2 = Moderate

3 = Large

4 = Major

Figure 2.2. Input-output direct-measurements transactions matrix for the measurement of

surface properties.

21
The central figure in each intersection

box is intended to be a measure of the magnitude of the transaction, taking into ac- count the amount of transfer of measurement

and other information, economic magnitude,

and the degree of measurement-intensi veness

In general, each supplier provides a different mixture of measurement services (column

3 of table 2.3) to each user so that the

central digits in each box are at best

semiquantitative estimates and in many cases meaningful intercompari sons cannot be made

from box to box.

The figure in the bottom left-hand corner

of each box is a measure of the rate of

change (growth) of the transaction, while

the number in the top left-hand corner is a measure of the importance, significance or

critical ity of the transaction, independent

of its magnitude. The digit in the top

right-hand corner of each box is a measure

of the adequacy or inadequacy of the measurement transaction. In nearly all boxes, the

latter digit has been coded 2 to indicate

that nearly all measurement services are being performed at the current state-of-theart although most users desire improvements

in accuracy and precision, greater specificity and sensitvity, and lower cost, as discussed earlier. All digits in the figure

must be regarded as subjective estimates of

factors which are difficult to define precisely and determine objectively. Nevertheless, the estimates provide a coarse summary

of the information given earlier in this

chapter concerning the technical infrastructure, measurement capability, and measurement needs of this part of the measurement

system and of the information to be presented

in chapters 3 and 4 concerning the applications and impact of the measurements and the

role of NBS, respectively.

2.5.2 Highlights re Major Users

The major user categories of surface mea- surements are (a) academic institutions, (b)

government laboratories, and (c) industrial

laboratories in the semiconductor, chemical,

petroleum, and metallurgical industries.

The types of measurements being made in

these laboratories will be discussed in

section 3.1.

3. IMPACT, STATUS, AND TRENDS OF MEASUREMENT SYSTEM

A survey of the more important methods of

surface characterization was given in

chapter 2. In this chapter, we will describe how the measurements are used, give

estimates of the costs and economic benefits

of the measurements, discuss the adequacy of

the measurements, and give estimates of the

future growth of measurement applications

and measurement needs.

3.1 Impact of Measurements

3.1.1 Functional, Technological, and

Scientific Applications

The diverse applications and impacts of

surface science and technology have been re- ferred to briefly in chapter 1 in excerpts

from two recent reports prepared under the

sponsorship of the National Academy of

Sciences [1,2]. We will give here representative examples of applications of sur- face-characterization measurements that have

been published in the literature, given to the author following personal inquiries

to users of particular instruments, given to the author by instrument manufacturers, or given to J. T. Yates, Jr. in a related NBS

survey. Some of this information was supplied on the understanding that particular

individuals, laboratories, or companies

would not be identified. To protect adequately such confidences and the related

proprietary information, the sources of

information presented in this section will

not be given. It can be stated, however,

that surface-characterization instruments

are in active use in many laboratories of

academic institutions, research foundations,

government agencies, and large companies in

the semiconductor, chemical, petroleum, and

metallurgical industries.

3.1.1.1 Applications for Surface Science

Surface science is performed at universities, research foundations, government

installations, and industrial laboratories.

At this time, there appear to be two distinct but related thrusts in fundamental

surface science.

First, considerable effort is being

applied theoretically and experimentally to determine the relationships between surface

composition, surface structure, and surface

electronic structure. Experimental work of

this type is often performed as far as possible on "ideal" surfaces (section 2.1)

in order to compare measurements with

22
theoretical work. Research is also performed

with "less ideal" or "real" surfaces, ranging from small particles, surfaces with

various amounts and types of defects, to surfaces of metastable and amorphous materials. Many of the measurement techniques

listed in table C.l of Appendix C have been

used for these measurements although the

techniques listed in section 2.2.2.1 are utilized to a greater extent.

Second, a large amount of effort is being

devoted to obtain a fundamental understanding of various electrical, optical, mechanical and chemical properties of the many

different kinds of surfaces just described

and of processes which occur on such surfaces. Specific problem areas are: adhesion, adsorption, diffusion from or to the

bulk, catalysis, contacts, corrosion, crystal

growth, epitaxy, evaporation, interface

properties and reactions, nucleation, oxidation, radiation effects, segregation, sur- face conductivity, surface diffusion, sur- face-phase changes, surface reactions,

surface thermodynamics, and thin-film growth,

structure, and properties. Experimental and

theoretical data are being obtained concur- rently in many of these areas and are being

related, where applicable, to the properties

of the constituent or interacting materials

or surfaces. This scientific work is motivated by needs for improved materials or processes and is usually closely coupled

with related developmental programs.

Applications of surface physics to the

computer industry, for example, are described

in a recent article by Branscomb [128].

Modern experimental surface science, as described above, must be performed with

materials that are well characterized. The

degree of characterization (section 2.1) may

vary, depending on the nature of the work,

but in most cases involves the surface

composition and often surface structure. In other cases, particular properties (e.g.,

adsorption, oxidation, and reactivity) are being correlated with the electronic structure at the surface. Thus, part of the

complexity (and cost) of surface science and

technology is due to the many facilities

that must be provided: surface generation

and processing equipment, surface-characterization instrumentation, and components to measure the particular surface properties or processes of immediate concern.

3.1.1.2 Applications for Surface Technology

Applied research and development work on surfaces, surface properties, and surface

processes is being performed at many government and industrial laboratories. We have

found in this survey that the principal form

of surface characterization is the determination of surface composition and that sur- face-composition information is obtained in

most cases by Auger-electron spectroscopy

(AES) or x-ray photoel ectron spectroscopy

(XPS), as could be inferred from table 2.2. We therefore show in this section specific

examples of the applications of AES and XPS;

similar examples have been found for ISS/SIMS

(ion- scattering spectroscopy/ secondary- ion

mass-spectroscopy) instrumentation

In the majority of present applications,

surface-composition information is obtained

for some relatively large area of a sample

(depending on the particular measurement

method), but it is believed that there will

be an increasing demand for measurements of

the distribution of particular elements or compounds in the plane of the surface. In- formation concerning the distribution with

depth of particular species is desired for

the majority of applications and is obtained

by gradual sputtering of the sample, a process known also as "depth profiling" and

"ion mi 1 1 ing.

Measurements of surface structure and

surface electronic structure are performed

at some laboratories in order to relate

these parameters to other desired surface

properties (e.g., reactivity, photocathode

response, stability, oxidation, diffusion,

electrical properties, etc.) for the development of new materials and processes.

3.1.1.2.1 Government Laboratories

The research and development laboratories

of civilian agencies and the Department of

Defense have widely different missions and

activities. There are, however, many sur- face-related, analytical, and developmental

programs at many installations despite the

diversity of objectives (e.g., space materials, energy programs, environmental applications, and defense). To illustrate this

diversity, we give in table 3.1 examples of

applications and uses of AES and XPS at eleven different laboratories; for some of

the larger laboratories, the list of

applications is almost certainly incomplete.

23
Table 3.1. Applications of Auger-electron spectroscopy (AES) and x-ray photoelectron

spectroscopy (XPS) in twelve government laboratories.

Laboratory Appl ication

(1) Migration of sodium ions in silicon dioxide under ion bombardment; segregation of impurities at grain boundary interfaces; fracture and embrittlement;

oxidation protection; activation and poisoning of thermionic cathodes; correlation of infrared reflectance for various materials with surface composition;

rocket engine catalysts (AES)

(2) Hydrogen permeation, hydriding, and gettering processes; development of

surfaces with increased corrosion resistance; role of surface composition on adhesive bonding and electroplating; poisoning of catalysts; relationship of

catalytic activity and surface morphology to crystallography, composition and

electronic structure; electrical contact studies; diffusion and surface

segregation in thin films; electrochemistry at thin solid films (AES, XPS)

(3). Improvement of reliability of equipment and components: corrosion problems

and problems in semiconductor devices; contamination on electrical contacts;

lubrication, cleaning and adhesion (AES, XPS)

(4) Detection and analysis of protein functional -group modification (XPS)

(5) Identify nitrogen and sulfur compounds in particulate soots: trace nature of

surface reactions on atmospheric pollutants (XPS)

(6) Material transfer in metal -polymer bearing systems (AES)

(7) Electronic structure of metal hydrides; development of superconducting materials to operate at higher temperatures (XPS, AES)

(8) Detection of different modes of sulfur (pyritic, sulfate, organic) in raw

coal (XPS)

(9) Oxidation, corrosion, and diffusion measurements (AES)

(10) Role of surface contamination in damage of lenses, mirrors, and windows used

with high-power lasers (AES)

(11) Development and characterization of photocathodes (AES)

(12) Role of first-wall contaminants on Tokamak performance (AES)

3.1.1.2.2 Semiconductor Industry

A more uniform pattern of applications, is

found in the semiconductor industry where

AES in particular is extensively used; SIMS

is used in applications requiring higher

sensitivity [129]. There are now three principal areas of application [4,30]:

(1 ) Process and Device Development . There is a continuing demand for new devices

with improved performance or properties. New

classes of materials are being developed as are new methods of fabrication and processing [128-130]. In addition, there is an increasing trend to microminiaturization and

greater complexity of devices.

(2) Process Control . AES is frequently

used to solve a variety of processing and

production problems such as:

(a) identification of stains, remnants

of a previous processing step, corrosion

products, compounds formed at interfaces by

diffusion, and dopants and contaminants in

semiconductors at various stages of processing;

(b) analysis of failures of lead bonding,

hermetic seals, and metallization adherence;

and

(c) establishment of effective cleaning

procedures. In these applications, decisions

are often made by comparing an Auger spectrum from the sample of interest with one from a sample known to be satisfactory; that

is, relative analyses are made on a given

instrument.

(3) Failure Analysis . Devices of increasing density and complexity and of

smaller size (microminiaturization) are being developed, but this trend has led to severe problems of reliability and yield.

Typical yields of MOS/LSI devices, for

example, are 5 to 8% of final assemblies.

24
Failure rates can be alarmingly high [131,

132], whereas reliability is crucial in large-scale civilian applications and in

defense and space applications. In a recent

analysis [132], 39'^ of device failures were attributed to surface-related defects and

18% of failures were attributed to metallization, oxide and bond defects. Many of these

failures are caused by problems at surfaces

or interfaces in the fabrication and processing of devices, such as residual con- tamination, adsorption of impurities, differential solubility, diffusion, void formation,

electromigration, film dewetting, modification of surface electronic properties, and

localized surface defects (e.g., dislocations, excessive roughness, and steps)

[131,133]. The poor yields often found in

the manufacture of complex LSI devices can

be attributed to inadequate quality control

during device manufacture; in particular,

surface contamination during processing has

been identified as a critical problem [132].

3.1.1.2.3 Chemical Industry

Table 3.2 shows examples of the applications of AES and XPS in the laboratories of

six large chemical companies. A common objective in all of these laboratories was the

development of improved catalysts.

3.1.1.2.4 Petroleum Industry

Table 3.3 shows examples of applications

of AES and XPS in laboratories of seven large petroleum companies. The development

and evaluation of process catalysts is again

a common feature of all laboratories.

3.1.1.2.5 Metallurgical Industry

Table 3.4 shows examples of applications

of AES and XPS in the laboratories of nine

metallurgical companies (including automobile manufacturers). The applications here

range from corrosion measurements and the

development of protective coatings to failure analysis, diffusion measurements,

segregation effects, fatigue, joining, wear

and embrittlement.

Table 3.2. Applications of Auger-electron spectroscopy (AES) and x-ray photoel ectron

spectroscopy (XPS) in six chemical -industry laboratories.

Laboratory Applications

(1) Heterogeneous catalysis and properties of catalysts; relation of surface

properties of fibers, plastics, and composites to adhesion and optical

qualities; corrosion studies (XPS)

(2) Development of improved process catalysts (greater selectivity, increased

activity, lower cost); relation of catalytic activity to structural defects;

adhesion phenomena: analysis of elastomers and substrates; role of surface

composition on composite bond strengths; development of new alloys with

lower corrosion rates, and longer process-container lines based on measurements of formation and breakdown of thin oxide films; interaction of surfaces

with processing environments; technical problems of polymer films; process

cleaning and wettability: surface adhesion (XPS, AES)

(3) Development of improved catalysts; reactions at fuel-cell electrodes; corrosion measurements (XPS, AES)

(4) Study of catalysis by metal particles (AES, XPS)

(5) Development of improved catalysts for manufacture of chemicals and plastics;

failure analysis and process development (AES)

(6) Development of improved catalysts: correlation of catalytic activity with

surface chemical species; acceptance testing of catalysts prior to use; elucidation of structure of complex organic molecules with N or S heteroatoms;

detection of trace impurities with electrochemical enrichment; migration of

ions following irradiation: changes of surface composition; treatment of

catalysts to stabilize physical properties in working environment; analysis

of surface coatings on particles in pigments (XPS)

25
Table 3.3. Applications of Auger-electron spectroscopy (AES) and x-ray photoelectron

spectroscopy (XPS) in seven petroleum-industry laboratories.

Laboratory Applications

(1) Improvement of catalysts in chemical process applications (XPS)

(2) Mechanisms of catalysis, and role of catalyst preparation and structure;

development of new catalysts and catalytic processes; catalyst evaluation;

corrosion on metal surfaces; wear phenomena; characterization of metals,

plastics, and composites (XPS)

(3) Surface species identification on active catalysts for petroleum refining or petrochemical processes; role of hydrogenating/dehydrogenating promoters on catalyst surfaces; types of solid acids on catalyst surfaces; surface species

in corrosion, wear and fracture (XPS)

(4) Characterization of surface composition and morphology on catalyst surfaces,

including poisons and promoters; passivation of metal surfaces against

corrosion; bonding of fibers; bonding of plastics; lubrication and wear (XPS)

(5) Catalyst evaluation and synthesis (XPS, AES)

(6) Catalyst evaluation and development; stability and regenerabil ity of catalysts

(XPS, AES)

(7) Elucidation of active catalyst sites and their optimization and stabilization; improvement of catalyst activity and selectivity; role of catalyst

support; effect of impurities on electronic states of the catalyst; role of

dispersion in metal, alloy, and other catalysts (XPS, AES)

26
Table 3.4. Applications of Auger-electron spectroscopy (AES) and x-ray photoel ectron spectroscopy (XPS) in nine metal 1 urgical -industry laboratories.

Laboratory Applications

(1) Failure analysis and quality control in laboratory of steel company (AES)

(2) Surface composition of powders and materials to be used for fuel cells;

diffusion and segregation of impurities in alloys; grain-boundary phenomena

in alloys; alloy foils; manufacturing problems: pickling, residuals of

cleaning, bonding problems in welds (AES).

(3) Poisoning of catalytic converter in automobiles; optimization of catalytic

converter; corrosion and wear of surfaces at high temperatures; coverage of

solid-state lubricants; surface reactions of exhaust gases in exhaust system

and control of gas composition (AES)

(4) Adherence and blistering of coatings; failure analysis; pickling rates;

optimization of surface treatments to improve bonding of fibers in composites;

temper embrittlement ; coatings to reduce eddy current losses in transformer

steels (AES)

(5) Catalytic reactions and materials in auto emission control; catalytic activity as a function of alloy surface composition; elimination of poisons on catalyst surfaces; analysis of surface layers (coatings on glass or chrome,

catalysts, oxides that affect joining, corrosion films, corrosion-protection

coatings, phosphating, and painting of surfaces); impurities at internal

interfaces (grain boundaries in steels and ceramics, fiber-matrix interfaces);

development of processes for wear-resistant coatings and decorative coatings

(AES)

(6) Surface reactions and nature of films that form on alloy surfaces during

processing; affect of surface films on welding, brazing, lubrication, wear, adhesion, electrical contact, resistance, radiation, durability (AES)

(7) Dependence of durability of anodic films on surface composition for different

preparation conditions; strength and durability of adhesive joints and the

relationship to surface composition; development of production line tests to characterize surface and near-surface composition of adherends; develop

passivating processes to improve resistance to corrosion, erosion, and stresscorrosion cracking and to give improved thermal and optical properties (AES,

XPS)

(8) Understanding of catalytic mechanisms and development of improved catalysts;

electronic structure of surface defects on small particles; bond strengths of

plated layers and of adhesive bonds; corrosion measurements (XPS, AES)

(9) Correlation of hardness and corrosion resistance of steels with surface

composition (AES, XPS)

3.1.1.2.6 Other Industries

Table 3.5 shows examples of applications

of the use of AES and XPS in the laboratories of ten companies engaged in a variety

of manufacturing industries ranging from

electronic instrumentation and equipment,

communications equipment, business machines,

and glass products.

3.1.1.3 Summary of Applications

We have shown here many applications of

surface-characterization measurements in

surface science and surface technology. The

most common form of surface characterization

is a qualitative determination of surface

composition, often as a function of position.

Surface-composition data is now being

27
Table 3.5. Miscellaneous industrial applications of Auger-electron spectroscopy (AES) and

x-ray photoelectron spectroscopy (XPS) in ten laboratories of manufacturing industries.

Laboratory Applications

(1) Quality control and failure analysis of incandescent lamps and lamp materials;

process evaluation; mirrors: surface contaminants; phosphor coatings (AES,

XPS)

(2) Identify surface composition and corrosion products or reactor fuel pellets;

diffusion studies of impurities in cladding; corrosion of pipes (AES)

(3) Surface analysis of organic and molecular solids; process development for

thin- film devices (AES, XPS)

(4) Determination of average particle size for dispersed catalysts (XPS)

(5) Lead monolayer lubrication in machining of steels: reduction of tool wear

(AES)

(6) Quality of films and interfacial bonds in compound device technology (AES)

(7) Studies of catalytic reactions by transition metals and perovskite oxides;

design of catalysts for chemical synthesis, energy conversion, and pollution

" abatement; passivation of surfaces; thin-film nucleation and growth, in-

^ eluding epitaxy; characterization of semiconductor and insulator surfaces

and interfaces; passivation of surfaces; development and fabrication of

semiconductor devices and precision resistors, capacitors, and conductors;

electronic structure of metal alloy and semiconductor materials; diffusion

of species in semiconductor devices (AES, XPS)

(8) Analysis of impurities and contaminants on semiconductor devices; phosphor

screen analysis; product and device development (e.g., photocathodes) (AES)

(9) Electronic properties of metal and semiconductor surfaces and of interfaces;

diffusion measurements; surface reactions; catalytic decomposition; surface

chemistry involving organics; corrosion chemistry; growth of oxide layers;

radiation chemistry; development of new materials with special properties

(XPS, AES)

(10) Role of surface composition on strength and durability of glasses: vaporization and migration during fabrication (AES, XPS)

obtained by Auger-electron spectroscopy, x- ray photoelectron spectroscopy, and ionscattering spectroscopy/secondary-ion mass spectroscopy (table 2.3). As pointed out in

section 2.3, these measurement techniques

have the ability to detect surface species

with a sensitivity much greater than that

available with other techniques. Although

commercial instrumentation based on these

new techniques has only been available for a short time, it is being used for a large

number of applications in many industries.

The industrial applications vary from problemsolving in analytical laboratories (e.g.,

failure analysis) to process and product

development, process evaluation and process

control. Examples of these applications

have been described in a number of recent

articles [134-143].

3.1.2 Economic Impacts - Costs and Benefits

We have estimated in section 2.2.2.2 that

the total sales of surface-characterization

instrumentation to date (i.e., within the

past ten years) is about $70M and that the

current sales volume is about $10M per year.

About two-thirds of this instrumentation has

been purchased by U.S. customers at an estimated cost of $7M per year. We assume that

500 instruments (LEED, AES, XPS, ISS/SIMS,

and IMMA) are currently in use in the U.S.

(table 2.3) and that each is operated by a scientist or engineer and a technician at a cost of $75K per year (combined salary and

overhead). The labor cost of making the

surface-characterization measurements is

thus about $37M per year. The total spending

for capital equipment and labor for these

28
measurements is then about $44M per year.

This total does not include the costs of

"homemade" or noncommercial instrumentation

developed for use of other measurement

methods (Appendix C), the associated labor

cost for their operation, and the costs of

additional ancillary equipment (e.g., residual gas analyzers, digital-data recording and

processing systems, etc.). The total spending for surface-characterization measurements

is therefore believed to be about S50M per

year.

The benefits of surface-characterization

measurements, economic and otherwise, cannot

be usefully quantified at present as they

involve government programs (e.g., defense

and energy), the short-term and long-term

benefits of scientific developments, work of

a proprietary nature (e.g., development of

improved catalysts), and a diversity of

applications (for which there could be more

than a single factor leading to the benefit).

We can, however, give a qualitative assess- ment of benefits for the following categories.

(1) Surface Science . The benefits here

are non-quantifiable in that one cannot

readily attach a particular monetary value

to a particular piece of scientific knowledge. There have been substantial developments in surface science in the past decade,

as evidenced by the amount of activity and

the scientific achievements noted in recent

articles and reviews [1-53,128]. These

developments have led to a greater fundamental understanding of surfaces, surface

properties, and surface processes which have

promoted most of the recent advances in

surface technology. The scientific developments have also led to the production and

utilization of new types of instrumentation

that have unique sensitivity for the detection and solution of surface-related

problems.

(2) Surface Analyses . A large fraction

of the surface-analysis equipment (e.g.,

AES, XPS, ISS/SIMS) in industrial laboratories is used for general -purpose analytical

or service work, particularly for failure

analysis [27,28,30,129,133-143]. In addition, the instrument manufacturers and a number of private analytical laboratories

perform analytical services on a fee-forservice basis.

It seems clear that the cost of these

analytical measurements must have at least a corresponding economic benefit. Furthermore, the surface-analysis instrumentation

discussed here has unrivalled sensitivity

for the detection of surface contaminants

and products; this instrumentation therefore

has a unique capability for solving problems

associated with or localized to a surface.

Although a single surface-analysis instrument costs typically $50-100K (table

2.3), one industrial user of AES equipment

remarked to the author that "the instrument

paid for itself in one week." That is, the

cost of a production-line failure for even short periods of time can be appreciably

greater than the cost of diagnostic analytical measurements.

(3) Surface Technology . As pointed out

in section 3.1.1.2, surface-characterization

equipment is used for the development of new

or improved processes and materials for a variety of applications. Again, it can be

reasonably assumed that the unique measurement capabilities of this equipment are generally being used to the economic advantage

of the user; the nature and magnitude of the

economic advantages can be inferred from the

examples of application given in section

3.1 .1 .2. Some individuals, in responding to re- quests for information on the nature of

their surface-characterization measurements,

specifically indicated that their activities

involved proprietary products, materials or processes. According to them, their surfacecharacterization measurements were either of

economic value to their company or of national benefit (in the case of a defense program) . One application, namely catalysis and the

development of improved catalysts, stands

out by its frequency in the responses made

for information for this report. Haensel

and Burwell [144] point out that catalysts

play a major role in the production of goods

worth more than $100 billion a year. Even slight improvements in the efficiency,

selectivity, stability, and life of a catalyst can have considerable economic impact.

Already, it is known that XPS has been used

for acceptance testing of industrial catalysts prior to use, thus avoiding the ex- pense of installation and unsatisfactory

operation (in this case, a saving of several

million dollars) [143]. Also, catalytic

activity is being correlated with the sur- face composition of binary alloys (determined by AES) [126].

Another important area of impact is

corrosion and the determination of the

integrity and efficacy of anticorrosion

coatings. It is known that AES is being

used for quality control, by a buyer and a seller, of galvanized coatings on steel used

for canning of food products. In another

case, AES was used to determine the cause of

paint blistering on the steel seats of a stadium, a multimillion dollar problem.

Precipitates on ceramic surfaces and the

material localized at corrosion pits have

29
been detected with a scanning Auger-electron

microscope.

In the semiconductor industry, intermaterial diffusion (and device failure) is retarded by the deposition of intermediate

layers; the significance and extent of

diffusion was revealed by AES. Improved

negative electron-affinity devices with many

applications are being developed with the

aid of AES.

(4) Government Programs . The surfacecharacterization measurements made in government laboratories benefit defense, energy,

space, and environmental programs, as noted

i n section 3.1.1.2.1.

More general benefits of surface science

and surface technology are discussed in the

next section.

3.1.3 Social, Human, Man-on-the-Street

Impacts

We have up to this point given examples

of specific surface-measurement activities

and programs at many laboratories. In some

cases, the objectives of the programs were

very clear while in others it could only be

assumed that the program objectives were of

value to the particular organization.

To give a clearer picture of the relevance

and impact of surface-characterization mea- surements, surface properties and surface

processes, we show in table 3.6 selected

portions of the report "Materials and Man's

Needs" sponsored by the National Academy of

Sciences [145(a)]. The panel that prepared

this report solicited the views of many

experts on current needs in applied materials

research and engineering. Table 3.6 gives a selection of the needs rated as "very high

priority" or "high priority" that relate to surface properties and processes in nine

major areas of public concern and societal

need: (1) communications, computers, and

control; (2) consumer goods; (3) defense and

space; (4) energy; (5) environmental quality;

(6) health services; (7) housing and other

construction; (8) production equipment; and

(9) transportation equipment. Clearly other

measurement techniques than those discussed

in this report will be required to develop

improved materials, products, or processes

for the various specific areas of applications. It is obvious, however, from this

table and the specific examples of surface

measurements and applications given earlier

in this chapter that surface-characterization

measurements are now having and will continue to have a considerable impact on programs

and policies of major public concern.

3.2 Status and Trends of the System

Information concerning the current status

of surface science, surface technology, and

of surface-related measurements has been

presented and discussed in several earlier

sections of this report. In chapter 1, we quoted from two recent National Academy of

Sciences reports that give independent

assessments of the significance of surface

science and the importance and relevance of

surface technology. Advances in surface

science and technology depend on reliable

methods of surface characterization. The

types of surface characterization were described in section 2.1 and the more important methods in section 2.2.2. The status

of present methods of surface characterization was summarized in section 2.3 together

with the more pressing needs for improved

measurements; detailed needs are given in

section 4.2.3.1. Information concerning the

interactions amongst suppliers and users of

surface-measurement services was given in

section 2.5 while the impact of surfacerelated measurements was described in

section 3.1. We have pointed out in chapter 2.2.2.2

substantial growth (about 25% per year) of

sales of surface-characterization instruments manufactured in the U.S.; the current

sales volume is about $10M per year. This

substantial growth rate is clearly related

to a number of factors, amongst them, the

establishment of public and private goals,

the growing awareness that the recently

developed measurement capability with previously unattainable surface sensitivity can

be successfully applied to a wide range of

practical problems and to a wide range of

research and development work, and the

belief among scientists and engineers that new concepts and measurement methods can be

developed to extend present knowledge of

surface processes and to provide other forms

of surface characterization.

30
Table 3.6. Impact Areas of Applied Research and Engineering that involve surface properties, process, or measurements, selected from the recent National Academy of Sciences

report "Materials and Man's Needs" [145].

(1 ) Communications, Computer, and Control

(a) Properties

Electrical: memories; solid-state circuitry, large-scale integration, display devices, Josephson devices, charge-coupled devices; miniaturization; reliability

Atomic structure: perfection; quality of crystals; surface effects; el ectromigration; ion implantation

Microstructure: defects in III-IV and II-VI semiconductors; defects in crystals;

films and epitaxy; interface imperfections; electromigration ; yields; metallization

Optical: optical properties; displays, solid-state lasers; optical communications;

optical storage

Dielectric: surface effects at semiconductor/insulator interfaces; encapsulation;

substrates

(b) Materials

Elemental and Compound Semiconductors: for electronic circuits; large-scale integration; displays; semiconductor memory; variable bandgap

Thin films: large-scale integration; control of metal 1 ization ; thin-film memories;

thin-film integrated optical devices; epitaxy; perfection of thin films

Ceramics: substrates, oxide layers, dielectrics; integrated optics; encapsulation;

laser windows

Glasses and Amorphous Materials: optical transmission; integrated optics; laser

windows; radiation-hand switches; glass for passivation

Inorganic, Nonmetallic Elements and Compounds: electro-optic microelectronics;

displays; modulators; detectors

(c) Processes

Vapor and El ectrodeposition , Epitaxy: yield and processing of large-scale integrated circuits; thin-film quality; epitaxy: greater miniaturization; control

of metal 1 ization

Chemical: corrosion; compatibility in environment; contacts; connectors; doping;

distribution of dopants; etching

Extraction, Purification, Refining: purification; synthesis ;^ characterization

Synthesis and Polymerization: encapsulants; conducting adhesives; coatings; seals

Radiation Treatment: ion implantation; radiation damage

Plating and Coating: encapsulation; environmental protection

31
Table 3.6 (continued)

(2) Consumer Goods

(a) Materials

Plastics: stronger plastics; wear resistance; less brittleness; nonflammable

plastics; impact-resistant plastics; biodegradable plastics;

Adhesives, Coatings, Finishes, Seals: Resistant polymers and rubbers; corrosion

protection; enamels; hot-water tank coatings; self-cleaning coatings for ranges;

reduce permeability of packaging films; bonding; fastening

(b) Processes

Plastics Extrusion and Moldings: reinforced plastic; composites; colloid properties; improved fibers

Synthesis and Polymerization: composite processing; biodegradable polymers; improved cross-linking; molecular architecture for special properties; improve fiber

strength by controlling molecular orientation

(3) Defense and Space

(a) Properties

Mechanical and Acoustic: mechanical properties of composites; high-temperature

materials; fatigue; corrosion fatigue; crack propagation; high-temperature fatigue;

creep resistance; fracture toughness; impact resistance; fatigue resistance; undersea equipment; materials for pressure hulls

Microstructure : dispersion hardening; microstructural stability; corrosion pitting; uniformity of mechanical properties; radiation-resistant materials; hydrogen

compatibility

(b) Materials

Composites: composites for ship construction; structural designs for composites;

improved fracture toughness of composites; fatigue-resistant composites; dispersion-hardened alloys; reliability of composites

Adhesives, Coatings, Finishes, Seals: high-temperature coatings; fabrication of

metal -nonmetal systems; integrity of polymer adhesives; degradation of adhesive

bonds; antifouling coatings for ships; coatings to reduce corrosion; low drag and

low contamination paints; room- temperature curing adhesives; thermal -control coatings; ablation materials; cements; sealants for deep-sea equipment

Joining: welding of titanium; weldable aluminum alloys; welding of dispersionhardened alloys; joining of composites; adhesion mechanisms; seals for undersea

repeaters

Testing and Nondestructive Testing: failure analysis; service life; failure prediction; nondestructive testing for welds

(4) Energy

(a) Properties

Chemical: batteries; higher energy density; improved electrodes; lower weight;

longer life; catalysts for batteries; new container materials for batteries;

corrosion of cables, of heat exchangers, of turbine blades; radiation effects on corrosion; high-temperature corrosion

32
Table 3.6 (continued)

Atomic Structure: solid-state electrolytes; hydrogen embri ttl ement ; superconducting materials for power transmission

Microstructure : Radiation resistance; swelling; void formation; blistering;

stability under high neutron fluxes; radiation- hard control equipment

Thermodynamic: combustion efficiency; thermoelectric power converters; magnetohydrodynamic conversion systems; electrohydrodynamic conversion systems

Mechanical and Acoustical: high-temperature materials for reactors, both for fuel

containers and converters; lightweight conductors; high-temperature alloys for

turbines; high-temperature bearings; creep; fracture toughness; high strength;

toughness; notch sensitivity; fracture propagation in pipeline materials

(b) Materials

Ceramics: high-temperature materials for burners; for plasma containment; highvoltage insulators; ceramics for turbine blades

(c) Processes

Testing and Nondestructive Testing: failure criteria; lifetime prediction; non- destructive testing of reactor components

(5) Environmental Quality

(a) Properties

Chemical: catalysts for automobile exhausts; pollution detection of control sys- tems; improved, cleaner extraction processes; improved benef iciation of ores; re- covery processes

Biological: handling corrosive, toxic, and dusty materials; biodegradable plastics

(b) Materials

Plastics: wear

(c) Processes

Extraction, Purification, Refining: improved extraction methods; improved incineration methods; control of pollution and environmental degradation caused by

mining and extraction

(6) Health Services

(a) Properties

Chemical: corrosion of implants; microbial corrosion; stress corrosion

Biological: biological response to implants; biocompatibil ity; rejection; toxicity; immunological response

Microstructure: adhesion; prosthesis/tissue interface; adhesion between implants

and tissue

Mechanical and Acoustical: artificial bone, teeth, tissue, membranes, and organs,

better filling material for teeth; fatigue; wear; alloys for joints

33
Table 3.6 (continued)

(b) Materials

Plastics: membranes; artificial teeth; dental adhesives; artificial heart valves;

encapsulants for implants; containers for blood

Prosthetic and Medical Materials: implants; artificial organs, bones, teeth,

tissue and membranes; compatibility and biological response

Fibers and Textiles: membranes, fine wires, organ replacements

Rubbers: artificial organs, tissue, membranes

Composites: for implants; bone and tooth replacements; joints; pins

Organo- and Organometal 1 ic Compounds: prosthesis-tissue interface; adhesion between bone and tissue; for implants

(c) Processes

Synthesis and Polymerization: dental adhesives; compatibility; interface between

tissue and prosthesis

Plastics Extrusion and Molding: precision forming; controlled porosity; artificial

organs; heart valves; membranes

Testing and Nondestructive Testing: quality control; methods to evaluate compatibility; characterization of properties of implants

(7) Housing and Other Construction

(a) Properties

Chemical: corrosion; atmospheric degradation

(8) Production Equipment

(a) Materials

Ferrous Metals and Alloys: harder dies; better cutting tools; better saws; rust

resistance

Nonferrous Structural Metals and Alloys: improved wear and fatigue properties

Lubricants, Oils, Solvents, Cleansers: tribology-lubricants; wear and abrasion

resistance

(b) Processes

Testing and Nondestructive Testing: quality control; fatigue failures

(9) Transportation Equipment

(a) Properties

Mechanical and Acoustical: fatigue; crack propagation; temperature cycling;

better bearings

Microstructure : super alloys for engines; corrosion resistance; stress corrosion

Chemical: corrosion resistance; stress corrosion; corrosion fatigue; high-temperature oxidation; catalytic converters for automotive exhaust

34
Table 3.6 (continued)

(b) Materials

Adhesives, Coatings, Finishes, Seals: Adhesives and sealants for aircraft; adhesives for automobile bodies, frames, and repairs; coatings for automobile

mufflers; coatings for turbine blades; seals for gas turbines; seals for Wankel

engines; refractory coatings

Lubricants, Oils, Solvent, Cleansers: wear, abrasion resistance

Ferrous Metals and Alloys: improved high-temperature properties; corrosion re- sistance

Nonferrous Structural Metals and Alloys: superalloys; high-temperature materials

for turbine engines

Plastics: composites

Composites: develop composites for use in engine and bodies of automobiles and

aircraft; joining metals

(c) Processes

Metal Deformation and Processing: nondestructive testing evaluation

Heat Treatment: improved strength; high-temperature properties

Material Removal : improved shaping methods

Joining: fasteners and bonding systems for aircraft and for automobiles; joining

methods for composite materials

At this point it is useful to recall that

the expression and establishment of major

"national goals" generally sets in motion a chain of organizational and technical re- sponses. A typical chain could include the

development and relationship of policies,

organizational approaches, technical approaches, hardware needs, applied materials

research, and basic materials research over

the necessary and appropriate time scales.

On this basis, one can appreciate how the

high-priority needs listed in table 3.6 for

improved materials, properties, or processes

relate directly to the particular goals

under which they are classified. Similar

relationships exist in industry between

corporate decisions (e.g., to enter a market)

and appropriate research and development

activities.

We believe that the following national

goals or policies will stimulate or require

continued growth in surface-measurement

capabil ity.

(1) Energy . The energy crisis is a com- plex matter of very high public concern that

will require a large number of governmental,

corporate, and individual actions for its

alleviation and eventual solution (by

Project Independence). Surface technology

will be required in at least the following

four areas of activity.

(a) Controlled Thermonuclear Reactors.

Whatever the type of reactor that may even- tually be developed as an alternate source

of energy, there will be a significant

problem in the design of the "first wall"

that will be exposed to the hot plasma [146-

148]. Radiation from the hot plasma will

strike the surfaces of the first wall (and

perhaps other components, such as diverters

and limiters) and will cause wall damage and

erosion and the release of gas and impurity

atoms into the plasma, thereby affecting

adversely the performance and efficiency of

the device.

A study group of the American Physical

Society has recently reported that [147]

"surface effects in CTR devices are strongly

influenced by impurities, by adsorbed surface

films, and by surface topography. Scrupulous attention must be paid to these points

in all investigations in this area." Surface analysis is therefore required to analyze the topmost layers of the wall

surface in order to gauge the efficiency of

initial cleaning operations and to identify

35
the nature of the equilibrium surface for

other performance criteria (e.g., sputtering, diffusion, and wear) [148].

(b) Laser Fusion. Laser-induced fusion

is another potential technique for energy

generation. In addition to the "first wall"

problems noted in (a) above, damage can occur to the optical components (mirrors,

windows, etc.) Damage thresholds are now strongly limited by surface defects (roughness, morphology of films) and by surface

impurities (contaminants introduced by

fabrication and by surface treatments) [149-

150].

(c) Liquefaction and Gasification of

Coals. Improved catalysts (with the neces- sary efficiency, stability, selectivity, and

cost) need to be developed to obtain liquid

and gaseous synthetic fuels from coal [126,

151]. Quantitative surface analysis will

enable improved catalysts to be scientifically engineered so that the" desired reactions

can be promoted and undesired components

(ash, sulfur, nitrogen) removed [152-155].

Identification of the nature and measurements

of the rates of specific surface (catalyzed)

reactions are also required so that improved

(e.g., alloy) catalysts can be designed.

(d) Hydrogen. Hydrogen has been proposed

as a major source of energy in the future

[156-157]. There are substantial surface

problems in hydrogen storage (as hydrides),

transport (due to hydrogen embrittlement)

and efficient use (e.g., in fuel cells).

(2) Defense . Surface technology is re- quired for the development of rocket-engine

catalysts, laser optical components, oxidation and corrosion protection, night-vision

devices, lubricants, microelectronic devices,

avoidance of fracture and embrittlement,

development of high-performance composite

and other materials, ablation materials,

adhesion and welding of materials, failure

analysis, and nondestructive testing; see also table 3.6.

(3) Advanced Materials . Needs for

advanced materials, as determined by a National Academy of Sciences panel , that

require surface technology are shown in

table 3.6. Similar needs have been highlighted in a recent series of articles on high- technology materials [158].

The prediction of the durability of

building materials and components, for

example, is becoming increasingly important

with the rapidly growing interest in lifecycle benefit-cost analysis. Many building

materials (e.g., concrete and paints) are composites in which internal interfaces have

an important bearing on performance. In addition, surface characteristics are of

vital importance in a wide range of building

materials (e.g., adhesives, building-joint

sealants, built-up roofing, electrical

terminations, paints, and coatings) for

which degradation occurs primarily by sur- face processes.

(4) Environment . Improved catalysts and

control methods are required for automobile

exhausts, power-station exhausts, and factory exhausts. Improved measurement methods

for determining the surface composition of

pollutant particles in the atmosphere (as a result of the discharges from fossil -fueled

power plants) and for determining the nature

and rate of chemical reactions on the sur- faces of these particles are urgently re- quired.

(5) Health and Safety . New bio-compatible and nondegradabl e materials are required

for prostheses and implants (table 3.6).

The development of such materials will

require the use of surface-characterization

measurements to assess corrosion rates in

the body environment. It is anticipated

that surface-measurement techniques will be

developed to characterize lipid membranes

and to determine how the transport of drugs

and carcinogens through such membranes can

be controlled.

(6) Productivity . Many industries are currently using surface-characterization instrumentation and surface technology to improve products, develop new products or to improve yield (section 3.1.1.2). It is

believed, based on the present activity and

the recent growth of activity, that this use of surface technology will continue and

probably intensify. Specific major areas of

development will probably include:

(a) the development of catalysts with

improved performance (efficiency, stability,

and selectivity) for existing and new pro- cesses in the petroleum and chemical industries ; (b) the development of improved coatings

and processes that can better withstand

corrosion and wear (e.g., by ion implantation [159]);

(c) the development of semiconductor

devices, particularly large-scale integrated

circuits, with greater yield and greater re1 iabil ity;

(d) the development of new components

(devices, memories, displays, optical systems) for improved performance in the commu- nications and computer industries; and

(e) the development of metal products

with improved strength and service life.

(7) Transportation . Needs for improved

properties, materials, and processes in the

automobile and aircraft manufacturing industries are shown in table 3.6.

36
In addition to the needs and developments

described above, it is believed that the

following factors will further stimulate

growth in surface-measurement capability.

(8) Surface Science . The development of

surface science has reached the point where

the properties of "ideal" surfaces (section

2.1) can be measured with reasonable confidence (section 2.3) and related to modern

theories of surfaces. It appears likely

that new and improved measurement techniques

and methodologies will be developed to characterize "real" surfaces. Developments

are anticipated in the following areas:

(a) methods to determine the local atomic

structure of real surfaces, perhaps from the

angular distributions of photoelectrons or

of excited ions (originating from chemisorbed

species)

(b) characterization of §mall particles

or clusters (diameters > 10 A) that are used

as practical catalysts tl7];

(c) methods, perhaps optical, to characterize surfaces in high-pressure environments (e.g., working catalysts) where electron-spectroscopic methods are unsuitable;

(d) solution of other basic problems

limiting the performance of industrial

catalysts [153];

(e) methods to develop and characterize

ultra-thin-film and microminiaturized semiconductor devices;

(f) determination of the relationship of

surface atomic structure and surface electronic structure for "ideal" and "real" surfaces to surface properties, such as reactivity, bonding, corrosion, durability,

wear, and lubrication; and

(g) determination of biophysical properties at biological surfaces and interfaces.

(9) New Instrumentation . The commercial

instrumentation now used for surface characterization (section 2.2.2) has directly

evolved from previously established scientific and technical knowledge. It is anticipated that instrumentation with improved

capabilities for surface characterization

will likewise be developed in the future

[160]; for example, the recent development

of a photoelectron microscope for imaging

biological surfaces has benefitted from

earlier work on electron optics and surface

physics and will probably stimulate new applications in biophysics [161].

(10) Quantification . Many present

methods of surface characterization are qualitative rather than quantitative (section

2.3). Although qualitative determinations

of surface composition have been extremely

useful for the solution of practical problems

(section 3.1), it seems intuitively clear

that the various types of instrumentation

will not be used to their full potential

until the results of the measurements can be

expressed in absolute terms with known

uncertainty.

(11) Legal . As the system for the mea- surement of surface properties becomes

better established (chapter 2), it is an- ticipated that reliable means for the determination of surface composition, for

example, will be used to specify the prepared

or working surface of a proprietary coating

or product (e.g., catalyst). Similar sur- face measurements will likewise be used in

the prosecution and defense of patent suits

where surface properties are involved.

(12) General Analysis . As the unique

sensitivity of instruments that determine

surface composition becomes more widely

known in the technical community, it seems likely that the instruments will be used to solve a wider range of problems than those

discussed in section 3.1; that is, there is no evidence of "saturation" in the present

range of applications. It is therefore

thought likely that within a decade most

major laboratories will have surface-characterization instruments routinely available

for analytical work, much as electron microscopes, mass spectrometers, chromatographs

,

x-ray analyzers, and spectrophotometers are available and in common use now. It is also

believed that the surface sensitivity of the

instrumentation discussed here could be

valuable in forensic applications.

37
4. SURVEY OF NBS SERVICES

NBS has many programs concerned with

properties of surfaces or of the surface

regions (of varying depths) of bulk matter.

These programs range from surface finish

measurements, electron probe microanalysis,

blood protein-polymer interactions, surface

reactions and catalysis, semiconductor

surface and interface properties, to corrosion measurements in biological, marine,

underground, and atmospheric environments.

In this chapter we will describe almost

exclusively NBS programs in the Surface and

Electron Physics Section of the Institute

for Basic Standards. There is considerable

cross-fertilization in the programs of this

section with those of the Surface Processes

and Catalysis Section of the Institute for

Materials Research, and reference will be

made to the latter programs where appropriate and to a recent unpublished study and

evaluation of measurement needs in heterogeneous catalysis by Dr. J. T. Yates, Jr. There is also a recently established program

in the Semiconductor Characterization Section

of the Institute for Applied Technology

concerned with methods for analysis of

semiconductor surfaces.

4.1 The Past

4.1.1 History of the Surface Physics Program

We describe here the initial background

and past accomplishments of the surface

physics program conducted in the Surface and

Electron Physics Section, a section which

has been in existence for only 3 years. The

elements of the program, however, have their

origins in the Electron Physics Section

founded in 1948 with Dr. L. Marton as Chief.

Although the personnel assigned to the

Electron Physics Section have changed over

the years and the programmatic objectives

have changed substantially, a particular

philosophy can be discerned in the section's

operation. A significant fraction of the

section's effort has always been devoted to improving the state-of-the-art of electronoptical devices which have been applied in

turn to a wide variety of current measurement problems. Specifically, new and improved types of electron guns, electron

monochromators , electron energy analyzers,

and electron lenses have been developed

together with new design principles and

data and with procedures to ensure that

electron-optical devices can be operated in

a satisfactory way. Although it has only

been in recent years that electron-spectroscopic devices have been intensively applied

to surface-related problems, surface characteristics have always been pertinent to the

development of electron-optical devices

(e.g., development of improved cathodes,

processing of photomul ti pi iers , and treatment of surfaces to minimize work function

variations or secondary-electron generation).

Figure 4.1 illustrates the programmatic

trends since 1955. In that year, the

largest effort was devoted to measurements

of inelastic electron scattering in solids

in order to determine the mechanisms of

contrast in the electron microscope. An effort to develop a novel x-ray microscope

led to the development of a field-emission

electron source that subsequently was used

in a commercial flash x-ray tube. This

project might be considered the forerunner

of the present surface-physics program. Two

years later, a field-emission program was established as part of an NBS program to study free radicals. Later, in 1961, a new program was established to measure work

functions of wel 1 -characterized singlecrystal planes of metals by a field emission

method. By this time, the program to measure inelastic interactions of electrons

with solids had diminished in size and was concerned principally with bulk properties

of solids and with applications in radiation

physics. In 1970, the Electron Physics

Section was disbanded. The surface and

solid-state related programs were incorporated into the Far Ultraviolet Physics

Section (where there was an existing uv surface photoemission program) while the

program to measure inelastic electron interactions in gases was incorporated into a new Electron and Optical Physics Section. A further reorganization took place in 1973

when the surface-physics and electronphysics elements of these two sections were combined to form a new Surface and Electron

Physics Section. At this time, increased

effort was applied to surface-related mea- surement problems by internal reprogramming.

The general and specific accomplishments,

to be described in sections 4.1.2 and 4.1.3,

respectively, are those related to surface

physics and must be viewed both in relation

to the current measurement needs (as discussed previously in section 3.2) and with

regard to the changing resources applied to these problem areas.

38
Electron Physics Electron Scattering Electron Electron X-ray

Section in Solids Inter- Schlieren microscope

1955 ference gas flow

(4f MY) (1? MY) (2 MY) (2 MY)

Electron Field- El Electron Scattering in Scattering electron Op, Gases

in Solids Emission

(2 MY) (2 MY) (i: (4t MY)

Far Ultraviolet

Physics Section

1970

Electron Field- Surf. uv Other Scattering electron Theory photoemission Section / in Solids Emission from surfaces Programs \

(2 MY) (2 MY) (1 my: (2? MY) (8* MY) .

'C Other El Electron / Section Op Scattering

Programs in Gases y (7 MY) (?) (2i

Electron and Optical Physics Section

1970

Surface and Electron Physics Section

1975

1

\ / 1

/

V\ //

/

/

/ /

\

\

\

\

Surface Surface El. uv Electron Elec tron \nalysis anc Theory Pol. photoemission Optics Scattering

El. Scat. from surfaces in Gases

(2 MY) (2 MY) (1 MY) (3 MY) (If MY) (2t MY)

1

I 10 15 MAN -YEARS

Figure 4.1. Prograrrmatic trends from the Electron Physics Section in 1 955 to the Surface

and Electron Physics Section of 1975 together with the corresponding number of full-time,

permanent, professional employees. "El. Opt." denotes electron optics, "El. Pol." denotes

electron polarization, and "El. Scat." denotes electron scattering in solids.

4.1.2 General Outputs of the Surface Physics

Program

There have been several major programmatic directions taken in recent years whose

general output will now be described.

(1) Field-electron emission measurement

techniques and work-function data. From

1961 to 1974, improved analyzers were developed to measure the energy distributions of

field-emitted electrons; these instruments

were used to make reliable measurements of

work functions of well-characterized singlecrystal planes. The measurement of workfunction changes was one of the few techniques available five to ten years ago to characterize surfaces. The instruments were

used to detect and characterize single

adsorbed atoms on a single-crystal plane,

observe surface states on metals, describe

the thermal field-emission process, and to obtain a surface density of electronic

states

(2) Photoel ectron emission measurement

techniques and data. In 1964 a program was initiated in the Far Ultraviolet Physics

Section to measure photoelectric yields from

clean and gas-covered metal surfaces in order to solve problems of plasma-wall

interactions in fusion reactors and to describe the performance of photocathodes in

space and other applications. In 1971, a new type of photoelectron analyzer was developed which has been used to observe and

39
monitor intermediate stages in the catalytic

decomposition of ethylene on tungsten, to observe metal surface states, and to observe

characteristic features identifying the

species and bonding geometry of adsorbed

gases on a metal surface.

(3) Surface Theory. Since 1968, theoretical effort supported jointly by the

Institute for Basic Standards and the

Institute for Materials Research has been

directed to deducing the basic significance

of surface spectroscopies and to stimulating

new surface measurements. Significant

accomplishments have been made in the areas of field emission, chemisorption , photoemission, and electron attenuation lengths in

solids. This effort was expanded in 1974.

(4) Surface Analysis. A program was initiated in 1973 to enable quantitative

surface analyses to be made by two popular

electron-spectroscopic methods (AES and

XPS). Measurements of electron attenuation

lengths have been made by two new methods,

and critical assessments made of attenuationlength and ionization cross-section data.

Experimental tests have been made of simple

models to describe the intensities measured

in AES and XPS experiments.

(5) Electron Optics. Improved techniques have been developed to calculate the

properties of electron lenses and to apply

this data to the design of improved electron-optical systems such as high-resolution

energy analyzers for field emission. Augerelectron spectroscopy and photoemission as well as other applications.

4.1.3 Specific Outputs of the Surface

Physics Program

We show in table 4.1 some specific sur- face-related accomplishments of the Surface

Physics Program that have occurred in the

last five years. For convenience, we have

subdivided these accomplishments into the

five program areas described in section

4.1.2. In practice, however, there have

been strong synergistic effects between

various program elements at all times.

We have identified in the table both an accomplishment and a related impact. For

the earlier accomplishments, the impacts

have already occurred among the users to be

described later in this chapter. For the more recent accomplishments, we have identified a potential impact based on our analysis of the status of measurements and/or the

need for data in a particular field.

4.1.4 Cooperation between Surface Programs

in the Institute for Basic Standards

and the Institute for Materials

Research

Modern surface science is an interdisciplinary endeavor involving chemistry,

physics, and metallurgy. The need to have

active cooperation between surface chemists

and surface physicists has long been recognized at NBS, and active collaboration

between these disciplines is an integral

strength of the Surface Physics program in

the Optical Physics Division and the Surface

Finish Program in the Mechanics Division of

the Institute for Basic Standards (IBS) and

the Surface Chemistry program in the Physical

Chemistry Division and the Corrosion program

in the Metallurgy Division of the Institute

for Materials Research (IMR). A theoretical

physicist. Dr. J. W. Gadzuk, is working on the theory of surface phenomena of concern

to both Institutes and his work is supported

equally by IMR and by IBS. In addition, an informal joint IMR-IBS seminar meets weekly

to discuss recent developments in surface

science.

Staff members from the IMR and IBS sur- face groups have jointly sponsored a number

of scientific conferences or lecture series

at NBS. Among these are: the 14th Field

Emission Symposium (1967), the lecture

series "Introduction to Surface Properties"

(1968), low-energy electron diffraction

seminars (1970, 1971), the 31st Physical

Electronics Conference (1971), and "The

Electron Factor in Catalysis" Workshop

(1975).

Surface science at NBS is widely recognized for its high quality. NBS is considered by many to be a premier institution in

surface science and has been characterized

as a national asset. The high external

reputation of surface-science activities at NBS transcends disciplinary or organizational

1 ines.

A joint research effort has been recently

initiated between IMR and IBS. Ultraviolet

photoelectron spectroscopy is being applied

to heterogeneous catalytic reactions using a spectrometer developed and built by IBS. Personnel from both institutes are currently

participating in this program, partially

supported by the Office of Naval Research,

and it is anticipated that NBS will make a significant impact by applying this technique to the identification and monitoring

of intermediate species in catalytic

reactions.

40
Table 4.1. Major Surface-Related Accomplishments of the Surface Physics Program from 1969

to 1974 and the nature of their impact.

Accomplishment Impact

(1 ) Field-emission Program

(a) Discovery of resonance tunneling

of adsorbed atoms on field emitter.

(b) Discovery of tunneling current from

a metal surface state.

(c) Technique developed to measure work

functions of single-crystal planes reliably.

(d) Observed high-energy "tails" on field-emission energy distributions.

(e) Observed smooth transition between

field emission and thermionic emission as emitter temperature was raised.

(2) Photoemission Program

(a) Observed catalytic decomposition of

ethylene on tungsten and structure characteristic of C-C, C-H, and C-W bonds.

(b) Observed characteristic features

for simple gases adsorbed on single-crystal

faces of tungsten.

(c) Observed surface state on metal

surface for the first time.

(d) Observed angular dependence in uv photoelectron energy distributions.

(e) Photoelectron yield of tungsten

changed when gases were adsorbed on surface

(in vacuum ultraviolet region).

A new technique for surface characterization

in chemi sorption experiments. Experiments

confirmed vi rtual -bound-state model of chemi

sorption.

Existence of a surface state is a standard by

which cleanliness of surface can be determined. Existence of the surface state has to be included in a complete description of sur- face electronic properties.

New measurement techniques that can be applied to characterize surfaces.

Theory developed concurrently showed that

this result was due to many-body processes.

Electron states between Fermi level and vac- uum level can be observed and used to determine shape of potential barrier. Barrier

transmission function used to interpret

photo-field emission results.

Powerful technique developed for monitoring

catalytic reactions as intermediate species

in complex reactions can be identified.

Spectra can be used as a library in later

work to identify intermediate species in sur- face reactions. Microscopic data for atoms

have been related to macroscopic properties

of adsorbed layers.

Surface sensitivity of photoemission could be

compared with that of field emission. Measure of cleanliness of a surface now exists

for photoemission experiments.

Angular distribution for an adsorbed layer

can be related (by theory) to the local bond

geometry of the adsorbate on the surface.

Showed sensitivity of photoyield to surface

conditions. Showed likely variations in calibrations of photocathodes with and without

exposure to gas.

41
Table 4. 1 continued

(3) Surface Theory Program

(a) Generalized theory of field emission

developed including many-body effects, dbands in transition metals and effects of

chemisorbed atoms.

(b) Junction-tunneling theory developed

to account for effects of impurities in the

barrier region and to relate tunneling

to one-dimensional density of states.

(c) Microscopic theory of alkali

atom chemisorption on metals developed.

(d) Surface-molecule theory of chemisorption developed that includes chemical

orbital and solid-state band effects.

(e) Theory of photoemission developed

for chemisorbed atoms and molecules.

(f) Theory of electronic relaxation

developed for photoemission.

(g) Theory of inelastic electron scattering in thin films developed.

(h) Theory of optical absorption by

adsorbed atoms developed.

(4) Quantitative Surface Analysis Program

(a) Two new techniques for the measure- ment of attenuation lengths of low-energy

electrons in solids developed.

(b) Procedure developed to compute

attenuation lengths.

(c) Experimental and theoretical data

on cross sections for ionization of innershell electrons evaluated.

(d) Measured AES and XPS intensities,

and compared with model predictions.

(5) Electron Optics Program

High-resolution improved state-of-the-art

electron energy analyzers developed for

field-emission, inelastic-electron- scattering, and photoemission measurements.

Used to provide unified theory of field emission. Many-body and band-structure effects

can be determined. Differences in local density of states on different crystal planes of

a metal can lead to different observed structures. Effects due to chemisorbed atoms can now be quantified.

Inadequacies of previous theories shown.

Current- vol tage characteristics can now be

engineered by appropriate doping.

Used to interpret work-function change and

desorption-energy experiments.

Results used for interpretation of experiments

of adsorbed atoms on surfaces. Bond and band

effects important in catalysis.

Theory shows significant angular anisotropies

in photoemission can be related to bonding.

Theory explains observed line asymmetries

and some satellites; intensities of the latter

are needed for quantitative analyses by x-ray

photoemission.

Results important for quantitative surface

analyses by x-ray photoelectron spectroscopy

and Auger-electron spectroscopy.

Optical techniques will be valuable probes of

surface conditions of catalysts in highpressure environments.

Quantitative analyses of surfaces by Augerelectron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) are needed for

many applications in industrial, government,

and industrial laboratories (Chapter 3).

Improved measurement capabilities have led to new ways of characterizing surfaces and to the marketing of commercial instruments based

on NBS designs.

42
4.1.5 Cooperation between Surface Programs

1n the Institute for Basic Standards

and the Institute for Applied

Technol ogy

A program has recently been initiated in

the Electronic Technology Division of the

Institute for Applied Technology (lAT) to evaluate techniques currently in use for the

determination of composition at surfaces, at interfaces, and throughout thin-film elements

of semiconductor devices. This division is

also interested in expediting the development and use of present and improved mea- surement techniques of established reliability. It is anticipated that there will be

close ties in the future between the related

IBS and lAT programs to develop standards

and reference materials required by the

semiconductor industry.

4.2 The present-scope of NBS Services

4.2.1 Description of NBS Services

Figure 4.1 shows programs of the Surface

and Electron Physics Section in 1975. All

of the experimental programs make use of

state-of-the-art high-performance electron

monochromators and/or electron energy ana- lyzers that have been designed and developed

as a result of the electron optics capability in the Section. An important feature of

the work of the Section is the strong synergistic coupling between theory and experiment at all stages of every project.

One recently established program, not described earlier, is an effort to develop

an efficient detector of electron spin

polarization. Such a detector, in conjunction with a new source of monoenergetic

spin-polarized electrons, would be used in

electron-scattering experiments to identify

exchange-scattering mechanisms and in diffraction experiments to determine the local

atomic structure [99]. The detector is also

expected to be used for measurements of the

polarization of field-emitted electrons as a function of their energy. The effort on the

electron-polarization project has increased

since 1975 while the effort on the uv photoemission and electron scattering in gases

projects has decreased.

Programs of the Surface and Electron

Physics Section involve most of the following eleven operations:

(1) Identification of a measurement

need (see also section 4.4);

(2) Development of a new or improved

measurement method, instrument, or theory,

(3) Application of that measurement

method or theory to a problem of current

scientific or technical concern;

43

(4) Analysis of the data and results so obtained in relation to the body of scientific knowledge;

(5) Development of new concepts;

(6) Development of measurement procedures ; (7) Acquisition of measurement data for

a sufficient number of materials and conditions to show the power or limitations of

the measurement method or theory;

(8) Careful measurement of selected

properties ("benchmark data") that can be

used as tie points for data analysis, refer- ence purposes (in relative measurements),

and calibrations of instruments;

(9) Preparation of compilations or critical reviews of available measurement

data and theories to meet the needs of those

working in a particular field;

(10) Frequent evaluations of the current

measurement needs in the particular technical comnunity during the course of the

program; and

(11) Frequent evaluations of technical

progress and, with item (10), consideration

of the need to redirect the objectives of

the program.

The results of the various steps of the

Section programs are disseminated to the

scientific and technical community through

presentations at meetings and scientific

conferences (often sponsored by professional

societies), technical reports (often to sponsors), articles in professional journals,

published reviews, correspondence, and

through consultations. In all of these

activities, knowledge is disseminated. In many cases, new results of scientific significance and various types of reference

data are distributed. In addition, measure- ment methodology, instrument performance,

design data, instrument designs, and com- puter programs are disseminated. Personnel

of the section have also been active in

standardization activities, at first through

a regional group of users of x-ray photoelectron spectrometers (the North-East ESCA

Users' Group) and, more recently, through

the ASTM Committee E-42 on Surface Analysis

(section 2.2.1 )

4.2.2 Users of NBS Services

The primary users of the measurement

services provided by the NBS Surface and

Electron Physics Section have been identified in section 2.5.1. These users benefit

from the information generated at NBS and

disseminated in the manner described above.

Secondary and other users (of which the

majority are other members of the same primary group) benefit in turn from the

further dissemination of knowledge,
instruments, procedures, and data distributed

by the primary users. Surface science and surface technology

are both relatively new, compared to many

other branches of science and technology,

and as some of the NBS surface-physics

programs have only been established recently,

a summary of "typical" applications of NBS

services with the implication that these

services have been utilized over many years

would not be warranted. Nevertheless, an assessment of the use of NBS services can be

gained from section 4.1.2 and table 4.1.

Users of these results and developments

would include the following:

(1) Designers of high-performance electron energy analyzers and other electronoptical instrumentation.

(2) Scientists who make use of the

sensitivity of surface-state spectral features to surface contamination in order to determine the cleanliness of their surfaces.

(3) Scientists and technologists who

need quantitative analyses of surfaces.

(4) Scientists working on the development of new or improved catalysts who need

to detect and monitor the presence of different chemisorbed species.

(5) Scientists who wish to deduce the

local atomic structure for atoms adsorbed on surfaces.

(6) Scientists and technologists who

need reliable work-function data for wellcharacterized single-crystal planes.

(7) Scientists who wish to determine

surface electronic structure by the various

measurement techniques.

(8) Scientists and technologists who

wish to know the efficiency of photocathodes

on instruments used on space flights.

(9) Scientists who wish to use optical

techniques to monitor the presence of adsorbates on surfaces.

(10) Scientists and technologists who

make use of the instruments and measurement

procedures developed at NBS.

(11) Scientists who make use of the

reference data generated at NBS.

(12) Users of x-ray photoelectron spectrometers who need to know how the transmission of different instruments varies with

electron energy.

4.2.3 Alternate Sources

4.2.3.1 Measurement Needs

Before discussing whether or not there

exist alternate sources for the measurement

services provided by NBS, it is desirable to summarize and review in this section the

present needs for such services. A summary

of the present measurement capability for

the determination of surface composition,

surface atomic structure, and surface electronic structure was given in section 2.3

together with a brief description of current

measurement needs. The lack of documentary

standards, adequate reference data, and of

standard materials was pointed out in

section 2.2. The overall need for improved

measurement capability and improved measurement services is expected to grow based on the growth of surface science and surface

technology in response to national needs and

the other factors and trends described in

section 3.2. Inasmuch as the most commonly

used form of surface characterization is the

determination of surface composition (section 3.1), we will summarize the most important measurement needs for this application in some detail

.

4.2.3.1.1 Measurement Needs for the

Determination of Surface

Composition

The most common methods for the determination of surface composition are Augerelectron spectroscopy (AES) and, to a lesser

extent, x-ray photoelectron spectroscopy

(XPS). These two el ectron-spectroscopic

methods of surface analysis have many common measurement needs.

(1) Initial excitation: ionization

cross sections as a function of electron

energy and the energy distribution of backscattered electrons (AES); photoelectric

cross sections in designated shells and

subshells (XPS).

(2) Electron transport: electron attenuation lengths as a function of electron

energy in different materials; anisotropies

in crystals; matrix effects; modelling of

electron transport; surface topography.

(3) Analyzer performance: transmission

function; resolution; effect of modulation

amplitude (AES); detector sensitivity.

(4) Geometry: relation of specimen

crystal 1 inity and orientation and possible

anisotropy of electron transport to location

and angular acceptance of analyzer.

(5) Measurement reliability: procedures

to insure that representative regions of a sample are being measured; homogeneity of

sample; transverse and depth variation of

composition (resolution); procedures to insure meaningful calibration and operation

of equipment.

(6) Radiation damage: electron and x- ray induced damage; desorption, decomposition,

polymerization

.

(7) Reference data: tabulations and

reviews of line positions and line shapes

44
for elements and compounds in XPS and AES;

role of chemical or local atomic environment.

(8) Standards: standard materials for

calibration of energy, intensity, and depthprofile scales; standards for determination

of measurement sensitivity.

(9) Procedures: procedures to determine composition from observed intensities.

(10) Sputter yields (for "depth-profile"

measurements): data for elements, alloys,

and compounds as function of ion type and

ion energy; ion-induced dissociation and

other damage; crater effects during analysis

[7].

Amongst these needs, we have identified

the following as the most pressing:

(1) Standards for calibration of the

analyzer energy scale;

(2) Standards for the calibration of

the analyzer intensity scale;

(3) Standards for depth profiling

(thickness standards);

(4) Other surface standards (section

2.2.4);

(5) Reference spectra and line-position

data;

(6) Attenuation-length data for electrons in solids;

(7) Inner-shell ionization crosssection data;

(8) Energy distribution and number of

backscattered electrons (AES);

(9) Procedures to derive the surface

composition from observed intensities;

(10) Sputtering yields of elements (and

their variation with chemical environment)

[7];

(n) Data for electron-beam or x-ray

beam- induced damage to specimens.

The techniques of ion-scattering spectroscopy (ISS) and secondary-ion mass spectroscopy (SIMS) have the following measurement needs [23,25,26,76-84,162]:

(1) Primary beam: characterization of

primary ion beam shape and current density.

(2) Scattering and ionization: ion

scattering cross sections (ISS); neutralization effects; ionization efficiency (SIMS);

matrix effects; role of molecular ions,

multiply-charged ions, self-polymer ions,

hydride ions, and primary ion-matrix molecular ions (SIMS); surface topography.

(3) Ion transport: Knock-on effects

(SIMS); channeling in crystalline samples

and orientation effects; energy distribution

of secondary ions (SIMS).

(4) Analyzer performance: transmission

function; resolution; detector sensitivity.

(5) Geometry: role of geometry in

sensitivity and resolution; role of orientation of crystalline sample.

(6) Measurement reliability: procedures to insure reliability of measurement

and homogeneity of sample; transverse and

depth variation of composition (resolution);

reliable operation of equipment.

(7) Ion damage: sputter yields and

matrix effects; ion-induced damage to sample; crater effects during analysis [7].

(8) Reference data: tabulations and

reviews of ISS and SIMS data for elements

and compounds.

(9) Standards: standard materials

(thin-film, insulator, and alloy standards).

(10) Procedures: procedures to obtain

composition data from observed intensities.

4.2.3.1.2 Measurement Needs for the

Determination of Surface Atomic

Structure

Methods for the determination of surface

atomic structure by low-energy electron diffraction (LEED) are still being developed.

The differences betv/een observed and com- puted intensities are still large enough to suggest that either the experimental data

have been obtained from inadequately characterized samples, the theoretical models are not sufficiently accurate or complete, or the derived structure data may not be as accurate as believed. The most satisfactory

methods of LEED data analysis are rather

complex and costly (in computer time), and

there is a need for the development of

simpler procedures of acceptable accuracy.

As LEED only gives information on the

surface atomic structure of ordered singlecrystal surfaces, there is a pressing need

for the development of other methods for the

determination of local atomic structure on less ideal surfaces, as pointed out in

section 2.3.

4.2.3.1.3 Measurement Needs for the

Determination of Surface

Electronic Structure

The theory of the "measurement process"

for most methods of determining surface

electronic structure is still not fully

developed. As a result, the advantages and

limitations of particular measurement techniques have only become apparent through

extensive intercomparisons of experimental

data. Improved measurement methods that

give more direct information on surface

electronic structure need to be developed

both for single-crystal and less ideal

surfaces. In view of the complexity of the

relevant theory, there is a need for the

continued empirical evaluation of the many

45
present (Appendix C) and anticipated measure- ment techniques.

4.2.3.1.4 Measurement Needs for Other

Surface Properties and Processes

Measurement of surface composition,

atomic structure, and electronic structure

are frequently made so that other surface

properties and processes (e.g., reactivity)

can be related to fundamental surface characteristics. It is therefore important that

the techniques of surface characterization

be compatible with other measurement or operational requirements but, in general,

this has often not been possible. For

example, a catalyst may have to operate in a high-pressure working environment (pressure

greater than one atmosphere) whereas mea- surements of surface composition by Augerelectron spectroscopy, say, have to be made

in an ultrahigh vacuum (pressure about 10"^

Pa) [163]. There is therefore need for the

development of special measurement methods

(e.g., optical techniques) that can be

calibrated against Auger-electron spectroscopy at low pressures and used at high

pressures. Methods of this type could also

be used to determine whether the composition

of a surface has changed on going from a high-pressure working environment to a lowpressure measurement environment. Special

measurement methods likewise need to be

developed for other applications and conditions (e.g., nondestructive testing of

integrated circuits, surfaces of fuel-cell

elements, surfaces of biological membranes,

surfaces of highly dispersed catalysts, and

surfaces of particulate pollutants in the

atmosphere)

.

4.2.3.2 Sources of Measurement Services

Many members of the industries and organizations listed in figure 2.2 have developed

or provided surface-characterization mea- surement services, as discussed in chapter 2 and indicated schematically in table 2.4.

Many important contributions have been made

by many individuals from industrial, government, and university laboratories to meet

some of the measurement needs listed in

section 4.2.3.1, particularly in the provision of reference data. These efforts,

however, do not usually represent a significant part of the organizations' missions.

Also, the results of such programs usually

do not involve most of the eleven significant

components of a successful measurementservice program listed in section 4.2.1 on account of various institutional, economic, or competitive constraints.

The need for an NBS role in supporting

the Surface Properties section of the

National Measurement system can be appreciated from the following quotations from

letters received from the manufacturers of

surface-analysis equipment and from industrial users of this equipment. These

letters were received in response to re- quests for comments on the need (several

years ago) for the then-proposed establishment of a NBS surface-analysis program and

(later) on the specifics of the program.

"Most of our Augor spectrometers will be

going into the analytical chemistry

groups in the various companies and

industries. The scientists in these

groups are typically chemists with ex- perience in the standard bulk chemical

analysis techniques. The first question

we always get when talking to these

scientists concerning equipment sales is 'to what accuracy can you tell me the

quantity of a species present on this

surface.' At the present time we cannot

be very confident or accurate with the

quantitative analysis because of the lack

of standard data.

(Instrument manufacturer, October 1971)

"... At the present time, the chemical

interpretation of photoel ectron spectra

is often confused by little-understood

surface effects occurring in a depth up

to 100 Angstroms. In general, we do not

understand or know the electron escape

depths, the depth dependence of surface

charging, the radiation-induced surface

conductivity or the nature of the chemical compound at the surface of the

sample. Methods for preparing samples of

known surface composition have not been

worked out. The effect of vacuum gases

on the surface characteristics as exhibited by photoel ectron spectra is not

understood at all.... Matrix corrections

for quantitative analysis by electron

spectroscopy have not been worked out. "Certainly our sales would increase if

electron spectroscopy could be made

quantitative. However, industry cannot

afford to do the basic research required

to establish this capability."

(Instrument manufacturer, October 1971)

46
We feel that there is a need for NBS to begin a program to measure and compile

data relevant to Auger and ESCA. This

should be not only electron escape depth,

ionization cross section, and surface

induced damages as a function of energy,

and material and surface preparation but

also to establish standards for perfor- mance such as

1. Spectrometer Calibration - (a) sta- bility, (b) accuracy, (c) resolution,

(d) signal to background, (e) signal

to noise, (f) signal level (intensity)

2. Relative line intensities

3. Charging effects

4. Standards.

There is a sufficient need for the data

for NBS to be involved. The individual

companies will never produce data that

can readily be compared."

(Instrument manufacturer, November 1971)

To summarize, I think it v/ould be most

helpful if the Bureau of Standards could

participate in the evolution of electron

spectroscopy. Much work remains to be

done to make these techniques quantitative. The development of standard cross sections as a function of electron energy

and of electron absorption for the emerging photoelectrons would be most helpful.

The development of standardized methods

of correcting for these matrix effects

would be a significant contribution. I sincerely hope you are in a position to launch such a program."

(Instrument manufacturer, December 1971)

I am very happy to see that you have initiated this program which I think can provide extremely useful information for

the users of AES and XPS equipment,

particularly with respect to quantitative

analysis.

From the user's point of view, there is

another area which adds confusion to the

quantitative capability of surface analysis techniques on practical surfaces, and

this is the surface topography. Variation in surface topography can cause great differences in absolute sensitivity

in a measurement technique such as Auger

electron spectroscopy, and perhaps you

may have some suggestions as to how to take this into account."

(Instrument manufacturer, June 1973)

"The factors which we find to be important

in a practical sense, are the ones you

have designated as (1) initial excitation, (2) electron transport or mean free

paths for inelastic scattering of electrons. Analyzer performance, in the sense of the instrument's intensity

response as a function of electron energy

is also a factor which must be accounted

for."

(Instrument manufacturer, July 1973)

"... We are most enthusiastic about the

(NBS) program and feel that it is important and desirable from both the user's

and manufacturer's point of view. The

problem with leaving this type of work to industry or equipment manufacturers is

competitive pressure and economics.

(Instrument manufacturer, September 1973)

"Yes there is a real need for quantifying

these measurement processes if one wants

to do serious work. Those who will go

into the more complicated systems approxi

mating applied ones will be grateful for

having a tool that will help them sort

out the mess

"Yes NBS should do this work. Why not us? Because we have enough to do to try to solve the energy problem. I think this

is a classic case of the definition

implied in spelling out NBS. Furthermore, many industries are hampered in a comparison effort by secrecy."

(Head of surface science group of a major

petroleum company, December 1972)

"It is extremely important to quantify these

measurement processes (XPS, AES) through

such media as round-robin testing."

(Director of a Materials Science Laboratory of a catalyst manufacturer, January

1973)

"Our surface problems are in the fields of

catalysis, adhesion, and corrosion. We

feel that significant progress cannot be

made in any of these areas without the

'new' surface techniques that you are speaking of.

"There is no question that there is a real

need for quantifying these measurement

processes. The state of the art is not

quantitative as yet. While information

can be gathered with present techniques,

the methods are far from optimized.

"Industrial scientists are interested in

information about specific materials and

processes. They would indulge in standardization only occasionally.

47
"Any standardization of a measuring apparatus requires "known" samples. One role

that NBS could play would be to standardize surface preparation techniques so that experiments can be systematically

repeated in several laboratories.

"Comparison of spectra on different Auger

and ESCA machines should also take ac- count of variations in the excitation

sources, different geometries for surface

preparation in situ, etc. That is, more

than just transmission functions need to be compared.

(Member of corporate research laboratory

of a major automobile manufacturer, January

1973)

"In the Semiconductor industry, the role of

surfaces on device properties has become

of vital importance. We have been aware

of this shift in emphasis from bulk to film to surfaces for some time. While

monitoring progress in characterization

techniques, it has become clear that the new surface techniques are not capable of

generating quantitative results. One of

the major reasons for this lack of quantitation is, of course, the lack of

standards.

"One of the most useful surface techniques

is Auger spectroscopy. This technique

can characterize surfaces to a depth of

10 to 20 angstroms and when coupled with

ion sputtering, can give in-depth composition analysis in 10-20 angstrom increments for several thousand angstroms.

Unfortunately, all of the analytical data

is at^ best semi -quantitative.

"It appears that the National Bureau of

Standards should be actively involved in

the generation of standards for surface

analysis; particularly for Auger spectroscopy. These same standards could be

used for photoelectron spectroscopy (PES,

ESCA). As part of this standards development, the development of quantitative

techniques would be essential."

(Director of Materials Characterization

Laboratory of a major manufacturer of semiconductor devices, December 1975).

"In the past few years, having applied the

Auger technique in semiconductor manufacturing methods and failure analysis, I felt an acute need for proper standards

for surface characterization. Often the

surface composition of a material is

critically dependent on the manufacturing

method and also on the manufacturer.

"Standards with accurately known impurity

concentration and location in depth (such

as ion-implanted species) would be very

desirable from the viewpoint of determining the minimum detectable limits of

each technique. Often the concentration

derived from the electrical parameters

such as resistivity, may not give the

true surface concentration of an impurity. In such cases it would be desirable

to have reference samples with accurately

known concentration of impurities, in

which one can have confidence rather than

depending on the 'hand-waving' evident in

the literature.

"There is also an acute need for thin film

samples of accurately known thicknesses.

Such samples will be of immense value in

determining the depth-resolution and the

sputter rates in the composition profile

measurement using AES and ion sputtering.

"For those experimentalists who are primarily concerned with the application of AES

in problem solving, the Auger spectra

from elemental samples have been compiled

(though not without minor errors) and

made available commercially. However,

this could not be said about the spectra

from all inorganic compound materials.

Often one has to search the vast literature for reference spectra and even then

one may not find the relevant spectra.

Compiling reference Auger spectra from

all inorganic compounds might be a prohibitive task. Nevertheless, it will be

of great value if such spectra from

materials one usually encounters in the

electronics industry were to be compiled

and made available to the user. In this

context, it will be further helpful to tabulate the 'chemical shifts' (if any)

in these material s

"I strongly feel that the NBS is the only

establishment capable of playing a key

role in providing standard samples and

reference spectra, one may need in the

proper characterization of a solid surface. I hope your laboratories will

undertake the task, immense as it may be,

of providing the necessary framework for

and resolving the confusion in surface

analysis.

(Member of technical staff of a major

manufacturer of semiconductor devices,

December 1975)

4.8
"From the discussions that occurred during

our recent ASTM E-2.02 Subcommittee for

Surface Analysis meeting and Subcommittee

Task Group meetings, the unanswered

questions concerning surface analysis

certainly far outnumber the answered

ones. It is the wish of each of our Task

Groups - AES, ESCA, SIMS, ISS - to quantify the analytical measurements of these

techniques. As you are aware, this

requires in many cases the knowledge of

parameters of fundamental nature as well

as theoretical procedures for making use of the measured data. Standard materials

and well-characterized surfaces are also

needed.

"We understand that NBS has undertaken work

to answer some of these questions and

make certain necessary measurements. We heartily endorse this program as a valuable undertaking for all those in the

field of surface analysis. We hope this

program will be successful. Please keep

us informed of your progress."

(Secretary of ASTM Subcommittee E-2.02 on Surface Analysis - now Committee E-42 on Surface Analysis, November 1975)

Present NBS programs have been selected

to be responsive to the measurement needs

listed in section 4.2.3.1 within limits set

by available personnel and funding. Specifically, programs now exist for the quantification of surface analyses, for the

determination of surface electronic structure, and the determination of surface

atomic structure (by the diffraction of

polarized electrons and through use of the

theory of the angular distributions of

photoemitted electrons), as indicated in

sections 4.1 and 4.2. It is anticipated

that new measurement methods for specific

applications in science and technology

(section 4.2.3.1.4) will continue to be

developed at NBS in conjunction with the

other elements (section 4.2.1) of our programs.

4.2.4 Funding Sources for NBS Services

As shown in figure 4.1, there are 8 fulltime professional employees in the NBS

Surface and Electron Physics Section (in

1975) devoted to surface-characterization

programs. In addition, a significant fraction of the electron optics program (1%

employees) leads to improved surface-characterization instrumentation. These activities involve an expenditure of $41 IK (FY 75)

of which $343K originates from directly

appropriated NBS funds. The other $68K is

received by contract from the Energy

Research and Development Administration for

measurements describing the interaction of

electrons with solids.

4.2.5 Mechanism for Supplying Services

The results of NBS programs are disseminated by a variety of mechanisms:

(1) papers published in scientific and

technical journals (see Appendix D);

(2) papers published in review journals

(see Appendix D)

(3) papers presented at regional , national, and international scientific

meetings;

(4) presentations at workshops;

(5) reports to sponsors;

(6) individual consultation;

(7) correspondence;

(8) participation in ASTM activities;

(9) distribution of computer programs;

(10) distribution of design data and

mechanical drawings of NBS instruments;

(11) visits to manufacturers of surfacecharacterization instruments; and

(12) visits to university, government,

and industrial laboratories.

In addition, members of the Surface and

Electron Physics Section have attained

positions of leadership in professional

societies, have participated in the planning

and organization of scientific conferences,

and are frequently asked to referee manu- scripts submitted to journals and to review

proposals submitted for support to various

government agencies.

4.3 Impact of NBS Services

The most significant recent NBS accom- plishments have been listed in table 4.1

together with assessments of the corresponding impacts. These accomplishments have

been disseminated by the methods indicated

in section 4.2.5 and are being used by

personnel in industrial, government, and

university laboratories, as shown in section

4.2.2.

The impact of NBS work (and the esteem in

which NBS personnel are held in the scientific and technical community) can be gauged

from the extensive number of citations to NBS work in the published work of others (as

listed in recent editions of the Saienae

Citation Index) and from knowledge that NBS

results and data are used frequently (often

on a day-to-day basis) in many laboratories.

NBS personnel are frequently invited to give

talks at major national and international

scientific conferences, to participate in

international science programs (e.g..

International Center for Theoretical Physics

at Trieste, NATO Advanced Study Institutes),

49
and to serve on committees of professional

societies (e.g., of the American Physical

Society, the American Vacuum Society, the

Physical Electronics Conference, and ASTM),

and on review panels. On this basis, it is believed that NBS personnel have earned a high reputation for impact and effectiveness.

A listing of recent NBS publications, by

the personnel associated with the programs

shown in figure 4.1, is given in Appendix D.

4.3.1 Economic Impact of Major User Classes

The users of NBS measurement services are affiliated principally with manufacturers of

surface-characterization instruments, government laboratories, university laboratories,

and laboratories of the semiconductor,

chemical, petroleum, and metallurgical

industries (sections 2.5 and 3.1). These

organizations are concerned with the advancement and application of fundamental

knowledge, the development and sales of

instruments to promote science and technology, the promotion of national defense and

public welfare, and the development and

marketing of a wide range of products that

are directly and indirectly of benefit to the public (computers, communication equipment, lamps, plastics, adhesives, catalysts,

petroleum products, automobiles, and aircraft), as pointed out in section 3.1. The

significance of surface measurements and

properties has also been emphasized in two recent reports sponsored by the National

Academy of Sciences [1,2].

NBS programs have supported and promoted

the development of surface science through

the development of improved measurement

methods and the provision of reliable reference data. Developments in surface science

have led to the development of commercial

surface-characterization instrumentation, to advances in the understanding of surface

properties and processes, and to advances in

surface technology. The recently established

NBS program to quantify measurements of

surface composition is now beginning to support surface technology.

4.3.2 Technological Impact of Services

The impact of surface-characterization

measurements in science and technology has

been discussed extensively in section 3.1 while the factors which will cause growth of

surface-measurement capability in the future were described in section 3.2. The nature

of the impact of NBS programs has been

pointed out in sections 4.1 and 4.2.2.

4.3.3 Payoff from Changes in NBS Services

The reorganization in 1973 that led to the formation of the Surface and Electron

Physics Section was the result of recognition by NBS management of the current

and growing importance of surface science

and surface technology, in some earlier years,

the surface programs had been often regarded

as subordinate to other priorities and programs. The recent reorganization has thus

provided a new focus and visibility for

surface-related measurements and surfacerelated problems. At the same time, some internal reprogramming led to the establishment of the surface-analysis program in

response to the measurement needs that had

become apparent to the staff over a period

of several years. Recently, a new program

has been initiated to develop an improved

source and detector of polarized electrons

that are expected to be used for many scientific and technical purposes.

4.4 Evaluation of NBS Program

The National Bureau of Standards has

the authority [164] to undertake "the study

and improvement of instruments and methods

of measurement" for "the determination of

physical constants and properties of materials when such data are of great importance

to scientific or manufacturing interests and

are not to be obtained of sufficient accu- racy el sewhere.

Needs for NBS services in response to current measurement problems are determined

from a variety of sources:

(1) Staff awareness of trends in sci- ence, technology, and of related matters of

public concern (e.g., energy crisis, environment, defense, health, and safety, etc.);

(2) Staff attendance at scientific con- ferences ; (3) Staff visits to university, government, and industrial laboratories;

(4) Staff visits to manufacturers of

surface-characterization instrumentation

;

(5) Staff participation in meetings of

ASTM committees;

(6) Individual contact with users of

surface-characterization instrumentation

;

(7) Examination of scientific and technical journals; and

(8) Suggestions made by external advisors (e.g., the Evaluation Panel of the NBS

Optical Physics Division which previously

has recommended strengthening and expanding

the surface-measurements program).
Decisions to undertake and continue

projects are based on the following con- siderations : (1) Assessments of the magnitude of the

need in relation to the corresponding impact

and benefits (perhaps through an "issue

study");

(2) Determination that similar work is not or is unlikely to be undertaken elsewhere (of the necessary quality);

(3) Determination of a likely time scale

for the work;

(4) Availability of resources (personnel,

funds, equipment); and

(5) Current policies of NBS management.

Present NBS surface-measurement programs

are thus the product of continuing input and

evaluation in response to the mandate ex- pressed in the NBS enabling legislation.

The success or adequacy of NBS programs is

gauged by NBS management, NBS Evaluation

Panels, and the reactions of the users of

NBS services.

Previous and current NBS surface-measurement programs are distinguished by the

following strengths:

(1) A creative and competent staff whose

work is recognized nationally and internationally to be of high quality;

(2) An integrated program involving

capability in instrument development and

design, experiment, and theory;

(3) Existence of a measurement capability and expertise in the forefront of the

field;

(4) Provision of a variety of services

ranging from new instruments, reference

data, data analyses, measurement procedures,

analyses of the "measurement process" for

various measurement methods, new concepts,

and calculations of material properties; and

(5) Significant impact on existing

measurement problems.

4.5 The Future

We would like to summarize here reasons

for believing that NBS surface-measurement

programs will be required in the future

(that is, for at least the next five years).

(1) Surface science and surface technology are both growing in importance

(chapters 1 and 3)

(2) Substantial measurement problems and

needs now exist (sections 2.3.4 and 4.2.3.1).

(3) Manufacturers of surface-characterization instruments have requested NBS to provide measurement services that support

use of these instruments. Proposed NBS

programs of this type have been endorsed by

both manufacturers and users.

(4) Applications for surface-characterization measurements are expected to in- crease (section 3.2)

Recommendations for NBS action are sum- marized in the next section.

5. SUMMARY AND CONCLUSIONS

We have presented an analysis of the

state of the National Measurement System for

the Measurement of Surface Properties. This

part of the National Measurement System is

distinguished principally by the fact that,

as yet, there is no formal system of the

type found in most other areas of physical

measurement (as discussed in the other

reports of this series).

We now give the principal findings and

recommendations resulting from the present

study.

(1) Surface science and surface technology are widely regarded as being "frontier" areas in which major scientific breakthroughs will occur and in which major

improvements in materials and processes will occur (chapter 1). Most of the significant

advances to date in surface science and the

significant developments and applications of

surface technology have occurred during the

past ten years (chapters 1 and 3).

Present national goals for solution of

the energy crisis, provision of an adequate

defense capability, control of environmental

pollution, increase of industrial productivity to improve the national economy, and the

development of advanced materials for the

automobile and aircraft industries and for

improved individual health and safety will

stimulate or require growth of surfacemeasurement capability (sections 3.1.3 and

3.2). Other factors which will stimulate

growth in surface-measurement capability are projected developments in surface science,

development of improved instrumentation,

development of quantitative methods for

surface characterization, legal needs, and

anticipated growth in the applications of

surface analysis (section 3.2).

The present growth of surface measurements has occurred in the absence of a formal measurement system (chapter 2). At

this time, measurements are based on informal conventions rather than formal definitions (section 2.1). There is no established system of documentary specifications,

and there is a complete lack of standards,

standard procedures, and standard materials

to support surface-related measurements

(section 2.2). The extent of this problem

has been recently realized and an ASTM

Committee on Surface Analysis has been

organized (section 2.2).

51
Recommendation 1. It is recommended that

NBS support surface science and surface

technology by establishing, through its own programs and through the stimulation of

organizations such as the ASTM Committee

E-42 on Surface Analysis, a satisfactory

measurement system for surface properties

.

(2) The large number of solid-surface

properties that can be measured have been

divided into two groups. The first group

contains properties that are used to characterize a surface, such as surface composition, surface atomic structure, surface

electronic structure, the nature and distribution of surface defects, surface topography, and the nature and area of exposed

facets. The second group contains derived

properties such as electrical properties,

optical properties, adhesion, bonding,

catalytic activity, plating, durability,

corrosion, decoration, grain-boundary segregation, lubrication, and reactivity (section

2.1). Many of these latter properties and

processes, of considerable scientific and

technological significance, depend in detail

on the composition, atomic structure, and

electronic structure of the surface (section

3.1). Improved products and processes

depend on the control, design, and measurement of these three surface characteristics

(chapter 3)

.

(3) The principal form of surface characterization in use at the present time is

the measurement of surface composition

(section 2.2.2). Determinations of the

distribution of particular chemical species across a surface and as a function of depth

from the surface are frequently required

(sections 2.1 and 3.1).

Other forms of surface characterization

(e.g., nature and distribution of defects on

a surface, the surface topography, and the

nature and area of exposed facets) are expected to be required in the future for

particular scientific and technical applications (sections 2.1 and 3.2).

(4) Most measurements of surface composition are performed by Auger-electron

spectroscopy and, to a lesser extent, by x- ray photoelectron spectroscopy, ion-scattering spectroscopy and secondary-ion mass spectroscopy (section 2.2.2). The sales of

these instruments are estimated to be $10M

per year with a present growth rate of 20 to 30% per year (section 2.2.2.2). It is

estimated that about 60% of the instruments

to determine surface composition are in use

in industrial laboratories, about 20% in

Federal Government laboratories, and about

20% in university laboratories (section

2.2.2.2). These surface-analysis instruments are used routinely to solve a wide

range of industrial problems in the semiconductor, chemical, petroleum, and metallurgical industries. The applications range

from process and device development, process

control, process evaluation to failure

analysis (section 3.1.1.2). The same instruments are being used in Federal Government laboratories for many purposes, for

example, in support of defense, space,

energy, and environmental objectives

(section 3.1.1.2.1). University laboratories frequently employ these instruments in

order that investigators can relate fundamental surface properties to surface composition (section 3.1.1.1).

The cost of surface-characterization

measurements is estimated to be about $50M

per year (section 2.2.2.2). Data concerning

specific economic benefits have been hard to isolate but the direct benefits to industrial laboratories, in particular, are believed to be substantially greater than

the cost of the measurements (section

3.1.2).

Most measurements of surface composition

are now qualitative rather than quantitative

(section 2.3.1). Manufacturers and users of

surface-analysis equipment have pointed out

the need for the development of methods and

the provision of reference data and refer- ence materials so that quantitative analyses

of surfaces with known accuracy can be

obtained (sections 2.2, 2.3, and 4.2.3).

These services cannot be provided on the

necessary scale at the needed rate by instrument manufacturers and users on account

of various institutional, economic, and

competitive constraints (section 4.2.3.2).

An NBS program to meet specific measurement

needs has been strongly endorsed by instrument manufacturers and representative users (section 4.2.3).

Recommendation 2. It is recommended that

NBS, through its own internal program and

through cooperation with the ASTM Committee

E-42 on Surface Analysis, develop methods

and provide reference data and reference

materials to enable surface analyses to be

made with known aoouraay using, initially.

Auger-electron spectroscopy and x-ray photoelectron spectroscopy and, later, secondary-ion mass spectroscopy and ion-scattering

spectroscopy

.

(5) The surface atomic structure of

ordered surfaces is now being determined by

low-energy electron diffraction (section

2.3.2). A variety of other measurement

techniques have been recently proposed for

the determination of the local atomic structure of surfaces which do not necessarily

have the long-range order needed to generate

an electron diffraction pattern (section

2.3.2).
Reaormendat-ton 3. It is recommended that

NBS explore and develop improved methods for

the determination of the looal atomic structure of surfaces.

(6) Many techniques are being used to determine surface electronic structure but

considerable uncertainty remains in the

proper interpretation, of the measurement

data (section 2.3.2).

Recommendation 4. It is recommended that

NBS theoretical and experimental effort be

directed to resolving the measurement problems in the determination of surface electronic structure.

(7) Most methods for the characterization of surfaces can be employed only in an ultrahigh vacuum environment and some of

these methods can only be employed on relatively ideal (i.e., single-crystal) surfaces

(section 2.3.4). There is a need for the

development of improved measurement methods

that will allow surfaces to be characterized

at higher pressures and that will enable the

composition and structure of disordered

surfaces, highly dispersed catalysts, biological surfaces, and pollutant particles in

the environment to be measured (sections

2.3.4 and 3.2). More sensitive measurement

methods need to be developed to identify

transient species on surfaces and the kinetics of reacting species (sections 2.3.4 and

3.2).

Recommendation 5. It is recommended that

NBS develop improved measurement methods for

the determination of the surface composition,

atomic structure, and electronic structure

of practical surfaces of significance in

science and technology.

(8) Many of the present users of sur- face-characterization instruments do not have extensive experience in surface science

or technology and have had difficulty in

selecting instruments to meet their needs or

in using these instruments satisfactorily

(section 2.2.5). With the present rapid

growth in surface science and technology,

there is a continuing need for short courses

and review articles that provide up-to-date

evaluations of instruments, techniques, and

methods of data analysis for specific types

of applications (section 2.2.5).

Recommendation 6. It is recommended that

NBS sponsor short courses and prepare status

reports as needed to assist existing and

potential users of surface instrumentation

to select and apply instruments, methods,

and techniques in order to efficiently solve

current industrial measurement problems.

(9) NBS programs in surface physics have

had considerable impact on the development

of surface science through the development

of new instruments and measurement methods,

the observation of new surface properties

and processes, the development of new

theories and concepts, the provision of

reference data, and the publication of data

compilations and critical reviews (sections

4.1 , 4.2, and Appendix D)

Until recently, the major goal of the NBS

effort has been to support and promote

surface science (sections 4.1 and 4.2).

Surface technology has grown substantially

within the last five years and NBS data has

been widely used for many applications

(sections 4.1 , 4.2, and 4.3)

Many measurement problems exist in sur- face science and technology (sections 2.2,

2.3, 3.1.3, 3.2, and 4.2.3.1). Significant

problems exist in determining the properties, particularly the relationships between

particular physical characteristics such as composition and particular surface processes

(such as corrosion, catalysis, adhesion,

lubrication, and wear). The basic science

needs to be developed so that surface properties can be understood from a fundamental

point of view and so that surface science

can be used to design improved products and

processes (section 3.2).

Recommendation 7. It is recommended that

NBS continue to support surface science and

surface technology through the development

of improved measurement methods, through

theoretical and experimental programs designed to show the significant relationships

between surface characteristics and surface

properties and processes, and through the

provision of reference data needed by the

scientific and technical community.

Effective response to the foregoing

recommendations should lead to the establishment of a satisfactory National Measurement System for the Measurement of

Surface Properties.
APPENDIX A. METHODOLOGY OF THE STUDY

Information for this report was derived

from a variety of sources, the most important being:

(1) background knowledge of the staff

of the Surface and Electron Physics Section;

(2) supplementary reading of relevant

recent journal articles, reviews, and books;

(3) presentations given at recent

conferences and workshops on surface science

and technology;

(4) conversations and correspondence

with users of surface-characterization

instruments

(5) visits to or conversations with

manufacturers of surface-characterization

instruments;

(6) conversations with members of ASTM

Subcommittee E2.02 (now Committee E-42) on Surface Analysis;

(7) letters sent to Dr. J. T. Yates,

Jr., of NBS in response to inquiries for a companion study;

(8) examination of customer lists

supplied by some manufacturers of surfacecharacterization instruments;

(9) phone calls to representative users

of surface-characterization instruments

(whose names were on manufacturers' customer

lists); and

(10) comments and suggestions made by

interested scientists.

The author is extremely grateful to the

many people who provided help and information for this report and who made constructive suggestions to improve the first draft

of the report.

APPENDIX B. SUMMARY OF RECENTLY-PUBLISHED BACKGROUND DOCUMENTS

1 . Title : Characterization of Solid Surfaces

Edited by : P. F. Kane and G. B. Larrabee

Publ ished : Plenum Press, New York, 1974 (670 pages)

Contains : 23 articles on different methods of surface characterization

W. C. McCrone: "Light Microscopy"

A. C. Hall: "Multiple-Beam Interferometry"

D. J. Whitehouse: "Stylus Techniques"

C. Laird: "Electron Microscopy"

0. Johari and A. V. Samudra : "Scanning Electron Microscopy"

P. F. Kane: "Field Ion Microscopy"

R. D. Dobrott: "X-ray Diffraction Methods"

D. M. MacArthur: "Electrochemical Techniques"

J. L. Seeley and R. K. Skogerboe: "Emission Spectrometry"

N. J. Harrick and K. H. Beckmann: "Internal Reflection Spectroscopy"

J. A. Keenan and G. B. Larrabee: "Radioisotope Techniques"

J. V. Gilfrich: "X-ray Fluorescence Analysis"

5. H. Hercules and D. M. Hercules: "Surface Characterization by Electron Spectroscopy

for Chemical Analysis (ESCA)"

D. Hanemann: "Resonance Methods"

M. C. Hobson, Jr.: "Mossbauer Spectroscopy"

W. D. Mackintosh: "Rutherford Scattering"

T. B. Pierce: "Accelerator Microbeam Techniques"

6. A. Hutchins: "Electron Probe Microanalysis"

W. L. Baum: "X-ray Emission Fine Features"

C. C. Chang: "Analytical Auger Electron Spectroscopy"

J. M. McCrea: "Mass Spectrometry"

D. V. McCaughan and R. A. Kushner: "Impurity-Movement Problems in Analysis Methods

using Particle Bombardment"

C. W. White, D. L. Simms, and N. H. Tolk: "Surface Composition by Analysis of Neutral

and Ion Impact Radiation"

Comment : A useful up-to-date compilation of articles. Some of the articles describe techniques that are not surface-sensitive as defined in this report.

54
2. Title

Edited by

Surface Science: Recent Progress and Perspectives

T. S. Jayadevaiah and R. Vanselow

Publ ished : CRC Critical Reviews in Solid State Sciences 4, Nos. 2 and 3, 1974 (426 pages) _

Contains: Proceedings of the International Summer Institute in Surface Science, University

of Wisconsin, Milwaukee, Wisconsin, August 27-31, 1973. Contains 21 articles on recent

developments of surface science.

P. H. Emmett: "Fifty Years of Progress in Surface Science"

L. K. Runnels: "Surface Statistics"

D. Robertson and G. M. Pound: "Heterogeneous Nucleation and Film Growth"

G. Ehrlich: "Surface Self-Diffusion"

J. P. Hobson: "Physical Adsorption"

R. Gomer: "Some Aspects of the Theory of Chemisorption"

A. J. Bennett: "Some Electric Properties of Solid Surfaces"

F. C. Tompkins: "Heterogeneous Catalysis: Reactions of Simple Molecules at Metal

Surfaces"

J. H. Sinfelt: "Heterogeneous Catalysis: Some Aspects of Catalysis by Metals"

A. N. Broers: "Recent Advances in Scanning Electron Microscopy of Surface Topography"

A. van Oostrom: "Surface Analysis by FIM and AP"

C. B. Duke: "Electron Solid Scattering"

J. C. Tracy and J. M. Burkstrand: "Recent Advances in Surface Characterization using LEED and Auger Electron Spectroscopy"

D. Lichtman: "Surface Characterization by Electron, Ion, Photon, and Surface Wave

Induced Desorption"

R. Greenler: "The Use of Thermal Desorption, IR Spectroscopy, and Ellipsometry for

Surface Analyses"

G. A. Somorjai and S. B. Brumbach: "The Interaction of Molecular Beams with Solid

Surfaces"

D. R. Franke: "Surface States"

R. F. Greene: "Surface Electron Transport"

F. Stern: "Quantum Properties of Surface Space-charge Layers"

A. Many: "Relation between Physical and Chemical Processes on Semiconductor Surfaces"

C. B. Duke: "Future Perspectives in Surface Science"

3. Title : Proceedings of the Second International Conference on Solid Surfaces

Publ i shed : Japanese Journal of Applied Physics, Supplement 2, Part 2, 1974 (920 pages)

Contains : Proceedings of the International Conference held at Kyoto, Japan, on March 25-29,

1974. Sixteen jnvited and many other papers are published. The invited papers are:

E. W. Muller: "Atom-Probe Field Ion Microscopes and High-Field Surface Effects"

H. D. Hagstrum: "Some Topics concerning the Electronic Characterization of Solid

Surfaces"

Y. Uemura: "Landau Levels and Electronic Properties of Semiconductor Interface"

M, Drechsler: "Crystal Shape Changes in Vacuum: Determination of Surface Quantities

on Field Emitter Crystals without and with Adsorbed Layers"

T. N. Rhodin and J. E. Demuth: "Chemisorption on (001), (110), and (111) Nickel

Surfaces"

R. Gomer: "Some Aspects of the CO-Tungsten System"

D. Haneman: "Review of EPR Investigations of Semiconductor Surfaces"

J. Horiuti: "Catalyzed Reactions by Solid Surfaces and Adsorption"

J. H. Block: "Field Ion Mass Spectrometry of Oxygen, Sulphur, and Selenium at Different

Metal Surfaces"

J. Kistemaker and H. E. Roosendaal : "Fundamental Processes in Surface Erosion by

Sputtering"

K. Kambe: "Theory of Low-Energy Electron Diffraction at Crystal Surfaces"

C. B. Duke: "Determination of the Structure of Solid Surfaces by Low-Energy Electron

Diffraction"

V. Heine: "The Theory of Electrons at Surfaces"

R. L. Park, J. E. Houston, and G. E. Laramore: "Comparison of Many-Body Effects in

Core level Surface Spectroscopies"

A. A. Maradudin: "Edge Modes"

W. E. W. Ludwig: "Theory of Surface Phonons in Diamond- and Zincblende-Lattices"

55
4. Title : Proceedings of the 21st National Symposium of the American Vacuum Society

Pub1 ished : Journal of Vacuum Society and Technology ]2^, No. 1, January-February 1975

(594 pages)

Contains : Proceedings of the National Symposium held at Anaheim, California, on October 8-

11, 1974. Contains many invited and contributed papers on a variety of topics pertaining to surface science, vacuum technology, vacuum metallurgy, and thin-film phenomena.

Topics of the sessions relevant to this report are: Welch Memorial Lecture: "The Development of Ion-Neutralization Spectroscopy" (H. D. Hagstrum)

Thin Film Symposium: Metallization

Insulating Films

Unique Properties

Film Growth and Characterization

Films for Energy Conversion

Surface Science Symposium: Interactions of Atoms with Surfaces

Structure of Chemisorbed Layers

Electronic Structure of Surfaces

Photoemi ssion Studies

Chemi sorption

Vacuum Science and Technology Symposium: Analytical Depth Profiling Techniques

Hydrogen-Metal Interactions

Ion-Material Interactions and Techniques

5. Title : The Solid-Vacuum Interface

Edited by : G. A. Bootsma and J. W. Geus

Publ ished : Surface Science 47, No. 1, January 1975 (412 pages)

Contains : Proceedings of the Third Symposium on Surface Physics, University of Utrecht,

The Netherlands, June 26-28, 1974. Many papers are published on the following topics:

electron spectroscopy; alloy surfaces; chemisorption on metals; semiconductor surfaces;

electron diffraction; nucleation and surface diffusion; ion scattering; secondary ion mass spectrometry; desorption studies.

6. Title : A Special Issue on Surface Physics

Published : Physics Today 28, No. 4, April 1975, pages 23 to 71 (April 1975)

Contains : Five articles on different aspects of surface physics.

J. R. Schrieffer and P. Soven: "Theory of the Electronic Structure"

P. J. Estrup: "The Geometry of Surface Layers"

D. E. Eastman and M. I. Nathan: "Photoelectron Spectroscopy"

R. L. Park: "Inner-shell Spectroscopy"

E. W. Plummer, J. W. Gadzuk, and D. R. Penn: "Vacuum- tunnel ing Spectroscopy"

7. Title : "Techniques for Elemental Composition Profiling in Thin Films"

By : J. W. Coburn and E. Kay

Publ ished : CRC Critical Reviews in Solid State Sciences 4, No. 4, 561-590 (September 1974)

Contains : A good, up-to-date summary of the measurement techniques used for surface

analysis, the techniques of depth profiling, and of the damage to surfaces by ion

bombardment.

8. Title : Electron Spectroscopy

Edited by : R. Caudano and J. Verbist

Publ i shed : Journal of Electron Spectroscopy and Related Phenomena, Vol. 5, 1974 (1 124 pages)

Contains : Proceedings of the International Conference on Electron Spectroscopy, Namur,

Belgium, April 16-19, 1974. Contains many papers on instrumentation, techniques, photoelectron production cross sections, photoelectron spectra, theoretical models, surface

studies, valence-band studies, and analytical applications of x-ray photoelectron spectroscopy.

56
9. Title : Surface Physics of Crystalline Materials

Edited by : J. M. Blakely Published : Academic Press, New York, 1975

Contains : Ten articles on different topics of surface physics.

J. A. Strozier, Jr., D. W. Jepsen and F. Jona: "Surface Crystallography"

J. A. Appelbaum: "Electronic Structure of Solid Surfaces"

H. J. Leamy, G. H. Gilmer and K. A. Jackson: "Statistical Thermodynamics of Clean

Surfaces"

J. M. Blakely and J. Shelton: "Equilibrium Adsorption and Segregation"

M. Henzler: "Electronic Transport at Surfaces"

H. P. Bonzel : "Transport of Matter at Surfaces"

J. W. Gadzuk: "Interactions of Atoms and Molecules with Surfaces"

R. L. Park: "Chemical Analysis of Surfaces"

M. Lagally: "Surface Vibrations"

D. Tabor: "Interactions between Surfaces: Adhesion and Friction"

10. Title : Aspects of the Study of Surfaces

Edited by : I. Prigogine and S. A. Rice

Publ ished : Advances in Chemical Physics 7J_ (John Wiley and Sons, Inc., 1974) 633 pages

Contains : Five review articles on surface physics and surface chemistry.

C. B. Duke: "Determination of the Structure and Properties of Solid Surfaces by Electron Diffraction and Emission"

R. Gomer: "Electron Spectroscopy of Chemisorption on Metals"

E. N. Economou and K. L. Ngai : "Surface Plasma Oscillations and Related Surface

Effects in Solids"

K. L. Kliewer and R. Fuchs : "Theory of Dynamical Properties of Dielectric Surfaces"

S. A. Rice, D. Guidotti, H. L. Lemberg, W. C. Murphy, and A. N. Bloch: "Some Comments

on the Electronic Properties of Liquid Metal Surfaces"

1 1 . Title : Surface Properties of Materials

Edited by : L. L. Levenson Publ ished : Surface Science 48, No. 1 (March 1975) 287 pages

C ontains : Proceedings of the Conference on Surface Properties of Materials, University of

Missouri, Rolla, Missouri, June 24-27, 1974. Contains sixteen articles on surface

properties and surface characterization.

P. Auger: "The Auger Effect"

C. C. Chang: "General Formalism for Quantitative Auger Analysis"

J. P. Rynd and A. K. Rastogi : "Characterization of Glass Surfaces by Electron

Spectroscopy"

J. E. Rowe, H. Ibach, and H. Froitzheim: "Photoemission and Energy Loss Spectroscopy

on Semiconductor Surfaces"

D. L. Mills: "The Scattering of Low Energy Electrons by Electric Field Fluctuations

near Crystal Surfaces"

R. L. Park: "Recent Developments in Appearance Potential Spectroscopy"

C. R. Brundle: "Elucidation of Surface Structure and Bonding by Photoelectron

Spectroscopy?"

J. E. Holliday: "Characterization of Surfaces by Soft X-ray Spectroscopy"

A. V. Crewe: "Electron Microscopes using Field Emission Source"

G. Slodzian: "Some Problems Encountered in Secondary Ion Emission Applied to Elementary Analysis"

H. B. Huntington, L. A. Turk, and W. W. White III: "Binding of an Adatom to a Simple

Metal Surface"

S. L. Bernasek and G. A. Somorjai: "Small Molecule Reactions on Stepped Single Crystal

Platinum Surfaces"

R. C. O'Handley and D. K. Burge: "Optical Studies of Chemisorption on Metals"

P. Halevi: "Absorption of Radiation by Impurities on Crystalline Surfaces"

B. B. Dasgupta, P. Kumar, and D. E. Beck: "A Simple Dispersion Relation for the

Surface Plasmon: Dependence on Electron Density Profile"

R. J. Bell, R. W. Alexander, Jr., C. A. Ward, and I. L. Tyler: "Introductory Theory

for Surface Electromagnetic Wave Spectroscopy"

57
12. Title : Treatise on Solid State Chemistry. Vol. 6. Surfaces

Edited by : N. B. Hannay

Publ ished : Plenum Press, New York, 1976

Contains : Ten articles on surface science

G. A. Somorjai: "The Structure and Thermodynamics of Clean Surfaces - Principles"

E. G. McRae and H. D. Hagstrum: "Surface Structure - Experimental Methods"

G. M. Rosenblatt: "Evaporation from Solids"

R.J.H. Voorhoeve: "Molecular Beam Deposition of Solids on Surfaces: Ultrathin Films"

T. N. Rhodin and D. L. Adams: "Adsorption of Gases on Solids"

T. E. Madey, J. T. Yates, Jr., D. R. Sandstrom, and R.J.H. Voorhoeve: "Catalysis by

Solid Surfaces"

F. H. Eisen and J. W. Mayer: "Ion Implantation and Channeling"

S. R. Morrison: "Semiconductor Surfaces"

W. Vielstich et al_. : "The Role of the Solid in Electrochemical Phenomena"

H. L. Frisch, G. L. Gaines, Jr., and H. Schonhorn: "Polymer Surfaces"

13. Title : Methods of Surface Analysis

Edited by : A. W. Czanderna

Publ ished : Elsevier, New York, 1975

Contains : Ten articles on surface analysis

G. K. Wehner: "The Aspects of Sputtering in Surface Analysis Methods"

D. Lichtman: "A Comparison of the Methods of Surface Analysis and Their Applications"

T. M. Buck: "Low-Energy Ion Scattering Spectrometry"

W. M. Riggs and M. J. Parker: "Surface Analysis by X-ray Photoelectron Spectroscopy"

A. Joshi , L. E. Davis, and P. W. Palmberg: "Auger Electron Spectroscopy"

J. A. McHugh: "Secondary Ion Mass Spectrometry"

J. M. Morabito and R. K. Lewis: "The Use of Auger Electron Spectroscopy and Secondary

Ion Mass Spectrometry in the Microelectronic Technology"

E. W. Miiller: "The Atom-Probe Field Ion Microscope"

J. H. Block and A. W. Czanderna: "Field Ion Mass Spectrometry Applied to Surface

Investigations"

H. G. Tompkins: "Infrared Reflection - Absorption Spectroscopy"

14. Title : Surface Physics of Phosphors and Semiconductors

Edited by : C. G. Scott and C. E. Reed

Publ ished : Academic Press, New York, 1975

Contains : Nine articles on characterization and properties of semiconductor surfaces

D. Haneman: "Atomic Structures of Surfaces"

R. 0. Jones: "Aspects of Surface State Theory"

F. Berz: "The Surface Space Charge Layer"

S. R. Morrison: "Theory of Adsorption"

C. E. Reed and C. G. Scott: "Techniques and Measurements"

F. Meyer and M. J. Sparnaay: "The Chemical and Physical Properties of Clean Germanium

and Silicon Surfaces"

C. G. Scott and C. E. Reed: "II-VI and III-V Compound Materials"

J. N. Zemel : "Gas Effects on IV-VI Semiconductor Films"

K. H. Zaininger: "The Effect of Surface States on Semiconductor Devices"

15. Title : The Physical Basis for Heterogeneous Catalysis

Edited by : E. Drauglis and R. I. Jaffe

Publ ished : Plenum Press, New York, 1976

Contains : 26 articles on the physical and chemical characterization of surfaces and on the use of modern surface science to study catalysts and catalytic reactions

58
16. Title : Interactions on Metal Surfaces. Vol. 4 of Topics 1n Applied Physics

Edited by : R. Gomer

Publ ished : Springer-Verlag, New York, 1975

Contains : Seven articles on the characterization of surfaces and the study of catalytic

reactions

J. R. Smith: "Theory of Electronic Properties of Surfaces"

S. K. Lyo and R. Gomer: "Theory of Chemisorption"

L. D. Schmidt: "Chemisorption - Aspects of the Experimental Situation"

D. Menzel : "Desorption Phenomena"

E. W. Plummer: "Photoemission and Field Emission Spectroscopy"

E. Bauer: "Low Energy Electron Diffraction (LEED) and Auger Methods"

M. Boudart: "Concepts in Heterogeneous Catalysis"

17. Titl

: Surfaces and Interfaces of Glass and Ceramics

Edited by : V. D. Frechette, W. C. LaCourse and V. L. Burdick

Publ ished : Academic Press, New York, 1974

Contains : 26 articles on the characterization and properties of glass and ceramic

surfaces.

18. Title : ARPA/NBS Workshop IV. Surface Analysis for Silicon Devices

Edited by : A. G. Lieberman

Publ ished : National Bureau of Standards Special Publication 400-23 (March 1976)

Contains : 22 articles on various methods for the analysis and characterization of

silicon and semiconductor surfaces

1 9 . Title : Secondary Ion Mass Spectrometry

Edited by : K.F.J. Heinrich and D. E. Newbury

Published : National Bureau of Standards Special Publication 427 (October 1975)

Contains : Ten articles on the practice of secondary-ion mass spectroscopy

H. Liebl : "The Ion Microprobe - Instrumentation and Techniques"

G. Slodzian: "Looking at the Collection Efficiency Problem through the Ion Microscope Optics"

P. Williams and C. A. Evans, Jr.: "High Mass Resolution Secondary Ion Mass

Spectrometry"

J. G. Bradley, D. Y. Jerome, and C. A. Evans, Jr.; "A Comparison of Mass Spectra

from Three Ion Probes"

C. A. Andersen: "A Critical Discussion of the Local Thermal Equilibrium Model for

the Quantitative Correction of Sputtered Ion Intensities"

J. M. Schroeer: "An Outline of Secondary Ion Emission Models"

J. A. McHugh: "Empirical Quantitation Procedures in SIMS"

J. F. Lovering: "Application of SIMS Microanalysis Techniques to Trace Element and

Isotopic Studies in Geochemistry and Cosmochemistry"

J. A. McHugh: "Factors that Influence an Elemental Depth Concentration Profile"

J. M. Morabito: "A Comparison of Auger Electron Spectroscopy (AES) and Secondary Ion Mass Spectrometry (SIMS)"

20. Title : Proceedings of the 22nd National Symposium of the American Vacuum Society

Publ ished : Journal of Vacuum Science and Technology 1_3, No. 1, January/February 1976

Contains : Proceedings of the National Symposium held at Philadelphia, Pennsylvania, on October 28-31, 1975. Contains many invited and contributed papers on a variety of

topics pertaining to surface science, thin-film phenomena, and vacuum science and

technology; electrical and chemical properties of interfaces; structural and mechanical properties of interfaces; properties of films and interfaces; thin films in tribology and mechanical properties of thin films; optical properties of thin films;

applications of thin films; thin film processes; structure of surfaces; structure and

analysis of surfaces; surface properties of III-V surfaces; chemistry at surfaces;

chemisorption; catalysis; interactions of atoms with surfaces; ion-material interactions and techniques; profile analysis by various methods)

59
21 . Title : Proceedings of the Third Annual Conference on the P hysics of Compound Semiconductor Interfaces

Published : J. Vac. Sci . Techno!. 13, No. 4, 749-964 (July/August 1976)

Contains : 37 articles on the characterization and properties of compound semiconductor

surfaces and interfaces

22. Title : Systematic Materials Analysis (Vols. 1, 2, and 3)

Edited by : J. H. Richardson and R. V. Peterson

Publ ished : Academic Press, New York, 1974

Contains : The following chapters pertaining to surface analysis:

G. Stupian: "Auger Electron Spectrometry" (Vol. 1)

H. H. Farrell : "Electron Diffraction: Low Energy (LEED)" (Vol. 1)

A. L. Smith: "Infrared Spectrometry" (Vol. 1)

J, J. Uebbing: "Ultraviolet Photoelectron Spectrometry" (Vol. 2) W. G. Proctor: "X-ray Photoelectron Spectrometry (ESCA)" (Vol. 2)

R. S. Carbonara: "Ion-Scattering Spectrometry for Surface Analysis" (Vol. 3)

23. Title : Electronic Structure and Reactivity of Metal Surfaces

Edited by : E. G. Derovane and A. A. Lucas

Publ ished : Plenum Press, New York, 1976

Contains : 17 articles on the theory, chemistry, reactivity, activity of metal surfaces

T. Rhodin and D. Adams: "Introduction to Phenomenological Models and Atomistic

Concepts of Clean and Chemisorbed Surfaces"

T. A. Grimley: "Survey of Current Ideas in the Theory of Chemi sorption by Metals"

G. Allan: "Electronic Structure of Transition Metal Surfaces"

N. D. Lang: "Density-Functional Approach to the Electronic Structure of Metal

Surfaces and Metal -Adatom Systems

T. B. Grimley: "Chemisorption Theory, Electronic Structure, and Reactivity of Metal

Surfaces"

T. Rhodin and D. Adams: "Electronic Properties of Clean and Chemisorbed Metal

Surfaces"

T. Rhodin and D. Adams: "Approach to Two Prototype Metal Adsorption Systems"

G. E. Rhead: "Atomic Structure and Thermodynamics of Pure and Two-Component Metal

Surfaces"

B. W. Holland: "Theory of L.E.E.D."

S. Andersson: "Applications of LEED to the Determination of Surface Structures on Metals"

J. W. Gadzuk: "Electron Spectroscopy of Surfaces via Field and Photoemission"

C. R. Brundle: "Electron Spectroscopy for the Investigation of Metallic Surfaces

and Adsorbed Species"

M. Barber: "S.I. M.S. Studies at Metal Surfaces"

J. Block: "Field-Ion-Mass Spectrometry Investigating Electronic Structure and Re- activity of Surfaces"

C. Naccache: "Spectroscopic Studies of Supported Metal Catalysts: Electron and

Ferromagnetic Resonance and Infrared Spectroscopy"

G. C. Bond: "Small Metal Particles: A Bridge between Theory and Practice"

V. Ponec: "Catalysis by Supported and Unsupported Metals and Alloys"

24. Title : Adsorption at Solid Surfaces

Publ ished : Surface Science 53 (December 1975)

Contains : Proceedings of the Second Interdisciplinary Surface Science Conference,

University of Warwick, March 17-20, 1975

60
25. Title : Surface Science: Recent Progress and Perspectives

Edited by : R. Vanselow and S. Y. Tong

Pub1 ished : CRC Critical Reviews in Solid State Sciences 6, Nos. 2, 3, and 4 (1976)

Contains : Proceedings of the International Summer Institute in Surface Science,

University of Wisconsin, Milwaukee, Wisconsin, August 1975. Contains 19 articles on recent developments of surface science.

E. W. Muller: "The Imaging Process in Field Ion Microscopy from the FEM to the AtomProbe"

P. Soven, E. W. Plummer, and N. Kar: "Field Emission Energy Distribution (Clean

Surfaces)"

J. H. Block: "Chemical Surface Reactions in the Presence of High Electric Fields"

B. Mutaftschiev: "Adsorption and Crystal Growth"

H. P. Bonzel : "Surface Diffusion of Metals: A Comparison of Intrinsic and Mass

Transfer Measurements"

L. Esaki and L. L. Chang: "Superfine Structures of Semiconductors grown by Molecular Beam Epitaxy"

J. G. Dash: "Recent Studies of Physisorbed Films"

W. A. Steele: "Monolayer Physical Adsorption on Crystal Surfaces"

T. B. Grimley: "Chemisorption Theory"

M. B. Webb and P. I. Cohen: "Structural Studies of Clean and Overlayed Surfaces

with an Application to Xe Adsorption on Ag"

R. L. Park and M. den Boer: "Surface Analysis using Electron Beams"

A. Benninghoven: "Surface Analysis by Means of Ion Beams"

W. E. Spicer: "Surface Analysis by Means of Photoemission and other Photon-stimulated Processes"

J. H. Lunsford: "Surface Analysis by Means of Magnetic Resonance Techniques"

J. A. Appelbaum and D. R. Hamann: "Quantum Physics and Chemistry of Surfaces"

T. Baker: "Controlled Atmosphere Electron Microscopy of Gas-solid Interactions"

T. E. Fischer: "Contributions of Surface Physics to Catalysis"

J. R. Arthur: "Surface Science in the Electronics Industry"

M. Kaminsky: "Surface Effects in Controlled Thermonuclear Fusion"

61
APPENDIX C. SUMMARY OF MEASUREMENT

TECHNIQUES THAT HAVE BEEN USED TO

CHARACTERIZE SURFACES.

Figure C.l shows a summary of the many

techniques that have been used to characterize surfaces; this summary has been adapted

from one prepared recently by Murday [4].

The key to the various acronyms is given in

table C.l.

TABLE C.l. KEY TO ACRONYMS SHOWN IN FIGURE C.l

AEAPS

AEM

AES

APS

ASW

ATR

BIS

CIS

CLCOL

CPD

DAPS

^^ADS

ELELL EELS

EMESESDI

ESDN

ESR

EXAFS

FDFDM

FDS FEM FEES

FIM FIM-APS

FIS

GDMS

GDOS

HEED

IIRS

IIXS IMMA

IMXA

Auger-electron appearance-potential spectroscopy

Auger-electron microscopy

Auger-electron spectroscopy

Appearance- potential spectroscopy

Acoustic surface-wave measurements

Attenuated total reflectance

Bremsstrahl ung isochromat spectroscopy

Characteristic isochromat spectroscopy

Cathodol uminescence

Colorimetry: ir, visible, uv, x-ray, and y-ray absorption

spectroscopy

Contact potential difference

(work-function measurements)

Disappearance-potential spectroscopy

Heat of adsorption measurements

Electrol uminescence

El 1 ipsometry

Electron energy-loss spectroscopy

Electron microprobe

Emission spectroscopy

Electron-stimulated desorption

of ions

Electron-stimulated desorption

of neutrals

Electron-spin resonance

Extended x-ray absorption fine

structure

Flash desorption

Field-desorption microscopy

Field-desorption spectroscopy

Field-emission microscopy

Field-electron energy spectroscopy

Field-ion microscopy

Field-ion microscope - atom probe

spectroscopy

Field- ion spectroscopy

Glow-discharge mass spectroscopy

Glow-discharge optical spectroscopy

High-energy electron diffraction

Ion-impact radiation spectroscopy

Ion-induced x-ray spectroscopy

Ion microprobe mass analysis

Ion microprobe x-ray analysis

INS - Ion-neutralization spectroscopy

IRS - Internal reflectance spectroscopy

JS - Ionization spectroscopy

ISD - Ion-stimulated desorption

ISS - Ion-scattering spectroscopy

ITS - Inelastic tunneling spectroscopy

LEED - Low-energy electron diffraction

LMP - Laser microprobe

LS - Light scattering

MBRS - Molecular-beam reactive scattering

MBSS - Molecular-beam surface scattering

MOSS - Mossbauer spectroscopy

MS - Magnetic saturation

NIRS - Neutral impact radiation spectroscopy

NMR - Nuclear magnetic resonance

PD - Photodesorption

PEM - Photoelectron microscopy

PES - Photoelectron spectroscopy

RBS - Rutherford backscattering spectroscopy

RHEED - Reflection high-energy electron diffraction

SC - Surface capacitance

SDMM - Scanning desorption molecule microscopy

SEE - Secondary-electron emission

SEM - Scanning electron microscopy

SI - Surface ionization

a{p) - Adsorption isotherm measurements

SUMS - Secondary-ion imaging mass spectroscopy

SIMS - Secondary-ion mass spectroscppy

SLEEP - Scanning low-energy electror/ probe

SRS - Surface reflectance spectrojscopy

STEM - Scanning transmission electron microscopy

SXAPS - Soft x-ray appearance - potential

spectroscopy

SXES - Soft x-ray emission spectroscopy

TE - Thermionic emission

TEM - Transmission electron microscopy

TL - Thermol uminescence

UPS - Ultraviolet photoemi ssion spectroscopy

XEM - Exoelectron microscopy

XES - Exoelectron spectroscopy

XPS - X-ray photoemi ssion spectroscopy

XRD - X-ray diffraction (glancing incidence)

62
DETECTED PARTICLE

PHOTON ELECTRON NEUTRAL ION PHONON E/H FIELD

ATR AEAPS

AEM

LMP

PD LMP

PD ELL AES

ESR PEM

EXAFS PES o

H IRS SEE

O

5d LS UPS

MOSS

NMR

SRS XRD

XEM

XES

XPS

APS AEAPS ESDN ESDI

BIS AEM SDMM

CL AES

CIS DAPS

EM EELS

;tron SXAPS HEED

SXES IS

ELEC LEED

SEE

RHEED

SEM

SLEEP

STEM

TEM

NEUTRAL NIRS SEE >ffiRS MBSS

a(p)

GDOS IMXA ISD GDMS

IIRS INS SDMM IMMA

ION IIXS SEE ISD

ISS

RBS

SI IMS

SIMS

PHONC ES

TL TE FD SI ASW

Q

^AW EL FEES EDM FIM CPD M

fa FEM FDS FIM-APS ! MS

ITS FIS SC

W i

Figure C.I. Outline of surface-characterization techniques.

63
APPENDIX D. LIST OF RECENT PUBLICATIONS

ON SURFACE-RELATED MEASUREMENTS BY STAFF OF THE INSTITUTE FOR BASIC STANDARDS

This appendix lists publications dealing with surface-related measurements by the NBS

staff who have been involved with the programs described in sections 4.1 and 4.2.

1. Condensation of Tungsten on Tungsten in Atomic Detail: Monte Carlo and Statistical

Calculations vs. Experiment, R. D. Young and D. C. Schubert, J. Chem. Phys. 42^, 3943

(1965) . 2. Condensation of Tungsten on Tungsten in Atomic Detail: Observation with the Field-Ion

Microscope, T. Gurney, F. Hutchinson, and R. D. Young, J. Chem. Phys. 42^, 3939 (1965).

3. Field Desorption of Thorium from a Field-Evaporated Tungsten Surface, R. D. Young, J. Appl. Phys. 36, 2656 (1965).

4. Differences in the Characteristic Electron Energy Loss Spectra of Solid and Liquid

Bismuth, C. J. Powell, Phys. Rev. Lett. 1^, 852 (1965).

5. Field Emission Ultramicrometer , R. D. Young, Rev. Sci. Instrum. 37^, 275 (1966).

6. Inelastic Scattering Cross Sections for 20 keV Electrons in Al , Be and Polystyrene,

N. Swanson and C. J. Powell, Phys. Rev. 145^, 195 (1966).

7. Plasmon Damping Metals, B. W. Ninham, C. J. Powell, and N. Swanson, Phys. Rev. 145 , 209

(1966) . 8. Effect of Surface Patch Fields on Field-Emission Work-Function Determinations, R. D. Young and H. E. Clark, Phys. Rev. Lett. 1^, 351 (1966).

9. Anomalous Energy Spreads in Electron Beams, J. A. Simpson and C. E. Kuyatt, J. Appl.

Phys. 37, 3805 (1966).

10. Anomalous Work Function of the Tungsten (110) Plane, R. D. Young and H. E. Clark, Appl.

Phys. Lett. 9, 265 (1966).

11. Electron Monochromator Design, C. E. Kuyatt and J. A. Simpson, Rev. Sci. Instrum. 38^, 103 (1967).

12. Characteristic Energy Losses of 8 keV Electrons in Liquid In-Al and In-Bi Alloys, C. J. Powell, Adv. Phys. 16^, 203 (1967).

13. Inelastic Scattering of Kilovolt Electrons by Solids and Liquids: Determination of

Energy Losses, Cross Sections, and Correlations with Optical Data, C. J. Powell, Health

Phys. 13, 1265 (1967).

14. Field Emission Ultramicrometer Checks Dimensions, Profiles without Contact, R. D. Young,

Machinery Magazine (1967).

15. 1.1.5. Electron Guns, J. A. Simpson, Methods of Experimental Phys. Vol. 4, Atomic and

Electron Physics, Academic Press, New York (1967).

16. 1.1.7. Special Sources of Monoenergetic Electrons, J. A. Simpson, Methods of Experimental Phys., Vol. 4, Atomic and Electron Physics, Academic Press, New York (1967).

17. Comparison of the Spherical Deflector and the Cylindrical Mirror Analyzers, H. Hafner,

J. A. Simpson, and C. E. Kuyatt, Rev. Sci. Instrum. 39, 33 (1968).

18. Characteristic Energy-Loss Spectra and -Im(l/e) for Amorphous and Polycrystal 1 ine

AI2O3, N. Swanson, Phys. Rev. 165^, 1067 (1968).

19. Excitation of L-Shell Electrons in Al and Al^O^ by 20 keV Electrons, N. Swanson and

C. J. Powell, Phys. Rev. 167_, 592 (1968).

^ 20. Excitation of K-Shell Electrons in Be by Soft X-rays and 20 keV Electrons, N. Swanson

and K. Codling, J. Opt. Soc. Am. 58, 1192 (1968).

21. 9.2. Interaction of Electrons with Solids, C. J. Powell, Methods of Experimental

Phys. Vol. 7, Part B, Atomic and Electron Physics, p. 275, Academic Press, New York

(1968).

22. Resolution Determination in Field Emission Energy Analyzers, R. D. Young and C. E. Kuyatt, Rev. Sci. Instrum. 39, 1477 (1968).

23. Characteristic Energy Losses of 8 keV Electrons in Liquid Al , Bi , In, Ga, Hg, and Au,

C. J. Powell, Phys. Rev. 175, 972 (1968).

24. Field Emission through Single Strontium Atoms Adsorbed on a Tungsten Surface, H. E. Clark and R. D. Young, Surf. Sci. U, 385 (1968).

25. Resonance Tunneling of Field Emitted Electrons through Adsorbates on Metal Surfaces,

E. W. Plummer, J. W. Gadzuk, and R. D. Young, Solid State Commun. 7, 487 (1969).

26. Analysis of Optical- and Inelastic-Electron-Scattering Data. Parametric Calculations,

C. J. Powell, J. Opt. Soc. Am. 59, 738 (1969).

27. Many-Body Tunnel ing-Theory Approach to Field Emission of Electrons from Solids, J. W. Gadzuk, Surf. Sci. 15, 466 (1969).

64
28. Band-Structure Effects in the Field-Induced lunneling of Electrons from Metals, J. W. Gadzuk, Phys. Rev. 182, 416 (1969).

29. Resonance Tunneling Through Impurity States in Metal -Insul ator-Metal Junctions, J. W. Gadzuk, J. Appl . Phys. 41, 286 (1970).

30. Analysis of Optical- and Inelastic-Electron-Scattering Data. II. Application to Al

,

C. J. Powell, J. Opt. Soc. Am. 60_, 78 (1970).

31. Analysis of Optical- and Inelastic-Electron-Scattering Data. III. Reflectance Data for

Beryllium, Germanium, Antimony, and Bismuth, C. J. Powell, J. Opt. Soc. Am. 5^, 214

(1970).

32. Resonance Transmission in Electron Emission from Surfaces with Adsorbed Atoms, J. W. Gadzuk, Surf. Sci . 18, 193 (1969).

33. Coupled Surface-Plasmon Modes in Metal-Thin-Film-Vacuum Sandwiches, J. W. Gadzuk, Phys.

Rev. B. 1, 1267 (1970).

34. Resonance-Tunneling Spectroscopy of Atoms Adsorbed on Metal Surfaces: Theory, J. W. Gadzuk, Phys. Rev. B 1, 2110 (1970).

35. Field-Emission Studies of Electronic Energy Levels of Adsorbed Atoms, E. W. Plummer and

R. D. Young, Phys. Rev. B 1, 2088 (1970).

36. A Comparison Between the Fermi-Thomas and Quantum Dielectric Response of a Metal Surface

to a Static Point Charge, J. W. Gadzuk, Surf. Sci. 23, 58 (1970).

37. Validity of Inelastic-Electron-Scattering Data in Determining the Metallic or Insulating

Properties of Adsorbed Atomic Layers, C. J. Powell, Phys. Rev. B 1, 4191 (1970).

38. Comparison of Optical Data for Sodium and Potassium with Interband-Transition Absorption

Theory, C. J. Powell, Optics Commun. 2, 87 (1970).

39. Surface States on Tungsten, E. W. Plummer and J. W. Gadzuk, Phys. Rev. Lett. 25^, 1493

(1970) . 40. Hot-Hole-Electron Cascades in Field Emission from Metals, J. W. Gadzuk and E. W. Pluirmer,

Phys. Rev. Lett. 26, 92 (1971).

41. Field Emission Energy Distributions of Hydrogen and Deuterium on the (100) and (110)

Planes of Tungsten, E. W. Plummer and A. E. Bell, J. Vac. Sci. Techno!. 9 (1971).

42. Reply to Comments on a Theory of Field-Induced Tunneling, J. W. Gadzuk, Phys. Rev. B 3_, 1772 (1971).

43. Virtual Impurity Level Density of States as Investigated by Resonance Tunneling, J. W. Gadzuk, E. W. Plummer, H. E. Clark, and R. D. Young, NBS Spec. Publ . 323 (1971).

44. Tunneling from Cambridge Surface States, J. W. Gadzuk, J. Vac. Sci. Technol . 9^, 591 (1971) . 45. Approach to Alkali-Metal Chemisorption within the Anderson Model, J. W. Gadzuk, J. K. Hartman, and T. N. Rhodin, Phys. Rev. B 4, 241 (1971).

46. Internal X-Ray Photoemission in Aluminum: Excitation of Electrons from the Valence Band,

C. J. Powell, Solid State Commun. 10, 1161 (1972).

47. High-Resolution Measurements of Auger-Electron and Photoel ectron Structure in the

Secondary-Electron Energy Distributions of Aluminum, Nickel and Copper, C. J. Powell,

Proc. International Conference on Inner Shell Ionization Phenomena and Future Applications, Atlanta, Ga. (1972).

48. Electron Spectroscopy of Chemisorbed Atoms, J. W. Gadzuk, IX Winter School of Theoretical

Physics in Karpacz, Poland (1972) {The Theory of Metals and the Many Body Troblem,

Vol. 11, 1 (1972)).

49. Structure on the High-Energy Side of the KL^^M Auger Peak from Solid Aluminum: Internal

Photoemission, C. J. Powell, Appl. Phys. Lett. 20 (1972).

50. Photoemission Observation of a Surface State of Tungsten, B. J. Waclawski and E. W. Plummer, Phys. Rev. Lett. 29, 783 (1972).

51. High-Resolution Measurements of the LoMp J-L ^ Transitions in Nickel and Copper, C. J. Powell and A. Mandl , Phys. Rev. Lett. 29^; 1 753 (1972).

52. High-Resolution Measurements of Auger-Electron and Photoel ectron Structure in the Secondary-Electron Energy Distributions of Aluminum, Nickel and Copper, C. J. Powell and A. Mandl, Phys. Rev. B 6, 4418 (1972).

53. Windowless Photoelectron Spectrometer for High Resolution Studies of Solids and Surfaces,

J. K. Cashion, J. L. Mees, D. E. Eastman, J. A. Simpson, and C. E. Kuyatt, Rev. Sci. Instrum. 42, no. 11, 1670 (1971).

54. Third-Order Aberration Coefficients of Electron Lenses, C. E. Kuyatt, S. V. Natali, and

D. DiChio, Proceedings Eleventh Symposium on Electron, Ion, and Laser Beam Technology,

University of Colorado, Boulder, San Francisco Press, Inc. (1971).

65
55. Accurate Calculations of Properties of the Two-Tube Electrostatic Lens. I. Improved

Digital Methods for the Precise Calculation of Electric Fields and Trajectories, S. Natali, D. DiChio, and C. E. Kuyatt, J. Res. Natl. Bur. Stand. 76A, 27 (1972).

56. Accurate Calculation of Properties of the Two-Tube Electrostatic Lens. II. FirstOrder Focal Properties and P-Q Curves, S. Natali, D. DiChio, E. Uva, and C. E. Kuyatt,

Rev. Sci. Instrum. 43, 80 (1972).

57. Accurate Calculation of Properties of the Two-Tube Electrostatic Lens. III. Aberration

Coefficients, C. E. Kuyatt, S. Natali, and D. DiChio, Rev. Sci. Instrum. 43[, 84 (1972).

58. Field Emission Deflection Energy Analyzer, C. E. Kuyatt and E. W. Plummer, Rev. Sci. Instrum. 43, 108 (1972).

59. Contrasting Valence-Band Auger-Electron Spectra for Silver and Aluminum, C. J. Powell,

Phys. Rev. Lett. 30, 1179 (1973).

60. Field-Emission Tails and Tunneling Lifetimes, J. W. Gadzuk and A. A. Lucas, Phys. Rev.

B 7, 4770 (1973).

61. Field Emission Energy Distribution (FEED), J. W. Gadzuk and E. W. Plummer, Rev. Mod.

Phys. 45, 487 (1973).

62. Semiautomated Data-Recording and Control System for an Electron Energy Analyzer, C. J. Powell, Rev. Sci. Instrum. 44, 1031 (1973).

63. Electronic Characterization of Submonolayer Films, E. W. Plummer, Monolayer and Submonolayer Helium Films, Symposium at Stevens Institute of Technology (1973).

64. Representation of Focal Properties of the Equal -Diameter Two-Tube Electrostatic Lens for

Computer Calculations, A. Galejs and C. E.. Kuyatt, J. Vac. Sci. Technol . 10, 1114 (1973).

65. Focal Properties of the Two-Tube Electrostatic Lens for Large Voltage Ratios, C. E. Kuyatt, D. DiChio, and S. V. Natali, J. Vac. Sci. Technol. 10, 1118 (1973).

66. Third-Order Aberration Coefficients of Electron Lenses. II, C. E. Kuyatt, D. DiChio,

and S. V. Natali, J. Vac. Sci. Technol. 10^, 1124 (1973).

67. Electron Energy Analyzer Design, C. E. Kuyatt, Proceedings of Conference on Electron

Probe Analysis and Electron Microscopy, New Orleans, La. (1973).

68. Field Emission as a Probe of the Surface Density of States, D. R. Penn and E. W. Plummer,

Phys. Rev. B 9, 1216 (1974).

69. Valence-Band Auger-Electron Spectra for Aluminum, J. W. Gadzuk, Phys. Rev. B 9^, 1978

(1974).

70. Surface Molecules and Chemisorption . I. Adatom Density of States, J. W. Gadzuk, Surf.

Sci. 43, 44 (1974).

71. Use of Matrices to Represent Electron Lenses. Matrices for the Two-Tube Electrostatic

Lens, D. DiChio, S. V. Natali, C. E. Kuyatt, and A. Galejs, Rev. Sci. Instrum. 45^, 566

(1974).

72. Focal Properties of the Two-Tube Electrostatic Lens for Large and Near-Unity Voltage

Ratios, D. DiChio, S. V. Natali, and C. E. Kuyatt, Rev. Sci. Instrum. 45, 559 (1974).

73. Attenuation Lengths of Low-Energy Electrons in Solids, C. J. Powell, Surf. Sci. 44, 29

(1974).

74. Third-Order Asymptotic Aberration Coefficients of Electron Lenses. III. Formulas and

Results for the Two-Tube Electrostatic Lens, C. E. Kuyatt, D. DiChio, and S. V. Natali,

Rev. Sci. Instrum. 45^, 1275 (1974).

75. Angular Distributions of Electrons Photoemitted from Chemisorbed Atoms, J. W. Gadzuk,

Solid State Commun. 15, 1011 (1974).

76. Photoelectron Spectra of the Decomposition of Ethylene on (110) Tungsten, E. W. Plummer,

B. J. Waclawski, and T. V. Vorburger, Chem. Phys. Lett. 28, 510 (1974).

77. Surface Molecules and Chemisorption. II. Photoemi ssion Angular Distributions, J. W. Gadzuk, Phys. Rev. B 10, 5030 (1974).

78. A New Form for the Third-Order Asymptotic Aberration Coefficients of Electrostatic

Lenses; Application to the Two-Tube Electrostatic Lens, D. DiChio, S. V. Natali, and

C. E. Kuyatt, Rev. Sci. Instrum. 46^, 71 (1975).

79. Determination of Electron Attenuation Lengths in Metals: Transmission through Thin

Adsorbed Films, M. Sunjic, D. Sokcovic, and J. W. Gadzuk, J. Appl . Phys. Jap. Suppl . 2,

Pt. 2, 753 (1974) (Proceedings Second Internatl . Conf. on Solid Surfaces).

80. Electron Spectroscopy of Chemisorbed Atoms and Surface Molecules, J. W. Gadzuk, J. Appl.

Phys. Jap. Suppl. 2, Pt. 2, 851 (1974) (Proceedings Second Internatl. Conf. on Solid

Surfaces)

81. Experimental Observations of Electronic Energy Levels at a Solid-Vacuum Interface, E. W. Plummer, B. J. Waclawski, and T. Vorburger, Proceedings of the Symposium on Electrocatalysis, San Francisco, 43 (1974).

66
82. Relaxation Energies in Chemisorption Spectroscopy, J. W. Gadzuk, J. Vac. Sci. Technol

12, 289 (1975).

83. Angular Dependence of UV Photoelectron Distributions for Oxygen Adsorbed on W(IOO),

B. J. Waclawski, T. V. Vorburger, and R. J. Stein, J. Vac, Sci. Technol. U, 301 (1975).

84. Determination of the Spin-Polarized Surface Density of States in Strongly Correlated

Metals by Field Emission: Theory, D. R. Penn, Phys. Rev. B 1J_, 3208 (1975).

85. Vacuum-Tunneling Spectroscopy, E. W. Plummer, J. W. Gadzuk, and D. R. Penn, Physics

Today 28 (1975).

86. Field Emission Work Functions, T. V. Vorburger, D. Penn, and E. W. Plummer, Surf. Sci.

48, 417 (1975).

87. Optical Properties of Adsorbate Atoms, A. J. Bennett and D. R. Penn, Phys. Rev. B 11,

3644 (1975). ~

88. Field-Ion Microscopy of Silicon, A. J. Melmed and R. J. Stein, Surf. Sci. 49^, 645 (1975).

89. The Dependence of the Tunneling Current on Density of States in Non-Superconducting

Junctions, D. R. Penn, Surf. Sci. 50, 125 (1975).

90. 5f-Electron Excitation Energies and the Coulomb Term, U, in the Light Actinide Metals,

J. F. Herbst and R. E. Watson, Phys. Rev. Lett. 34, 1395 (1975).

91. Excitation Energy Dependence of Core-Level X-Ray-Photoemission-Spectra Line Shapes in

Metals, J. W. Gadzuk and M. ?unjic, Phys. Rev. B U, 524 (1975).

92. Measurement of the Surface Density of States by Field Ionization, D. R. Penn, Surf. Sci.

52^, 270 (1975).

93. Observation of Polarized Electrons by Davisson and Germer, C. E. Kuyatt, Phys. Rev. B 12, 4581 (1975).

94. Interaction of Atoms and Molecules with Surfaces, J. W. Gadzuk, Surfaoe Physios of

Materials, Vol. II, 339 (1975).

95. Extra-Molecular Relaxation Energies for Embedded in an Electron Gas, J. W. Gadzuk,

Chem. Phys. Lett. 36, 606 (1975).

96. Angle-Resolved Photoemission from Chemisorbed Layers: Further Theoretical Considerations, J. W. Gadzuk, Surf. Sci. 5^, 132 (1975).

97. Angle-Resolved Photoemission from Crystal -Field Split d Shells of Adsorbed Atoms, J. W. Gadzuk, Phys. Rev. B 12^, 5608 (1975).

98. Photoemission for Xe Physisorbed on W(IOO): Evidence for Surface Crystal -Field Effects,

B. J. Waclawski and J. F. Herbst, Phys. Rev. Lett. 35, 1594 (1975).

99. Cross Sections for Ionization of Inner-Shell Electrons by Electrons, C. J. Powell, Rev.

Mod. Phys. 48, 33 (1976).

100. Cross Sections for Ionization of Inner-Shell Electrons by Electron Impact, C. J. Powell,

J. Vac. Sci. Technol. 13, 219 (1976).

101. Electron Attenuation Lengths for Free-Electron-Like Metals, D. R. Penn, J. Vac. Sci.

Technol. U, 221 (1976).

102. UPS Studies of Virgin CO on W(IOO), T. V. Vorburger, D. R. Sandstrom, and B. J. Waclawski, J. Vac. Sci. Technol. 13, 287 (1976).

103. Can Chemisorption Bonding Shifts be Separated from Relaxation-Energy Shifts in PhotoElectron Spectroscopy?, J. W. Gadzuk, J. Vac. Sci. Technol. 13, 343 (1976).

104. 4f Excitation Energies in Rare-Earth Metals: Relativistic Calculations, J. F. Herbst,

R. E. Watson, and J. W. Wilkins, Phys. Rev. B U, 1439 (1976).

105. Effect of Ground State and Excitation Potentials on Energy Levels of Ni Metal, R. E. Watson, J. F. Herbst, L. Hodges, B. I. Lundqvist, and J. W. Wilkins, Phys. Rev. B 13^, 1463 (1976).

106. Improved Microwave-Discharge Source for UV Photoemission, T. V. Vorburger, B. J. Waclawski, and D. R. Sandstrom, Rev. Sci. Instrum. 47, 501 (1976).

107. Core Level Shifts in the 3d Transition Metals and Tin, R. E. Watson, M. L. Perlman,

and J. F. Herbst, Phys. Rev. B 13, 2358 (1976).

108. Quantitative Chemical Analysis by ESCA, D. R. Penn, J. Electron Spectrosc. 9, 29 (1976).

109. Photoelectron Spectra of Adsorbed Species on Tungsten, E. W. Plummer, B. J. Waclawski,

T. V. Vorburger, and C. E. Kuyatt, Prog. Surf. Sci. 7, 149 (1976).

110. Electron Spectroscopy of Surfaces via Field and Photoemission, J. W. Gadzuk, Electvonio

Structure and Reactivity of Metal Surfaces, Plenum Publishing Corp. (1976).

111. Comnent on "Field Emission as a Probe of the Surface Density of States," D. R. Penn,

Phys. Rev. B M, 849 (1976).

112. Screening Energies in Photoelectron Spectroscopy of Localized Electron Levels, J. W. Gadzuk, Phys. Rev. B U , 2267 (1976).

113. Coulomb Term U and 5f Electron Excitation Energies for the Metals Actinium to Berkelium,

J. F. Herbst, R. E. Watson, and I. Lindgren, Phys. Rev. B 14 , 3265 (1976).

67
114. Vibrational Excitation in Photoemission Spectroscopy of Condensed Molecules, J. W. Gadzuk, Phys. Rev. B M , 5458 (1976).

115. Absolute Yields of Auger Electrons from Beryllium and Aluminum under Proton Bombardment:

Determination of the Attenuation Lengths of Low-Energy Electrons in Solids, C. J. Powell,

R. J. Stein, P. B. Needham, and T. J. Driscoll, Phys. Rev. B, to be published.

116. Angle Resolved Auger Surface Spectroscopy, J. W. Gadzuk, Surf. Sci . , to be published.

117. Angle-Resolved Photoemission from Crystal-Field-Split Adatom Levels, J. F. Herbst, Phys.

Rev. B, to be published.

118. Angle-Resolved Photoemission from Physisorbed Atoms, J. F. Herbst, Proceedings Photoemission from Surfaces Conference, Noordwijk, The Netherlands (1976), to be published.

119. Determination of the Be KVV-Auger-Electron Attenuation Length in Be using 160 keV Protons, P. B. Needham, T. J. Driscoll, C. J. Powell, and R. J. Stein, Appl . Phys. Lett.,

to be published.

120. Displacement of Hydrogen by Carbon Monoxide on the (100) Face of Tungsten: A Photoemission and Thermal Desorption Study, T. V. Vorburger, D. R. Sandstrom, and B. J. Waclawski, Surf. Sci., to be published.

121. Effective Crystal Fields in the Rare Earth Pnictides, J. F. Herbst, P. Bak, and R. K. Watson, Proceedings International Conference on Magnetism, Amsterdam, The Netherlands

(1976).

122. Electron Mean Free Paths for Free-Electron-Like Materials, D. R. Penn, Phys. Rev. B, to be published.

123. Electron Transmission Measurements of Electron Mean Free Path in Supported Thin Films

from 1-5 keV, R. J. Stein, Surf. Sci., to be published.

124. Emission of Polarized Electrons from Solids, M. Campagna, D. T. Pierce, F. Meier, K. Sattler, and H. C. Siegmann, Adv. Eleatronics and Electron Physios, L. Marton, ed.

,

to be published.

125. Evaluation of Formulas for Inner-Shell Ionization Cross Sections, C. J. Powell, NBS

Special Publication, to be published.

126. Evidence for the Distortion of C^H. and C2H2 Chemisorbed on W(IOO), T. V. Vorburger,

B. J. Waclawski, and E. W. Plummer, Chem. Pnys. Lett., to be published.

127. Many Body Effects in Photoemission, J. W. Gadzuk, Photoemission from Surfaoes, J. Wiley,

publisher, B. Feuerbacher, B. Fitton, and R. Willis, editors, to be published.

128. Plasmon Satellites in X-ray Photoemission Spectra, J. W. Gadzuk, Phys. Rev. B, Comments

and Addenda, to be published.

129. The Role of Electronic Structure in Catalysis, J. W. Gadzuk and R. E. Watson, NBS Spec.

Publ . , to be published.

130. Secondary Electron Energy Distribution in High Energy Photoemission, D. R. Penn, J. Vac.

Sci. Technol . , to be published.

131. Theory of the Electron Energy Loss Spectrum in Core Level X-ray Photoemission from

Solids, D. R. Penn, Phys. Rev. Lett., to be published.

132. Time Scales and Plasmon Satellites in XPS, J. W. Gadzuk, Proceedings of Photoemission

from Surfaces Conferences, Noordwijk, The Netherlands, to be published.

68
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[164] Title 15 of United States Code 272.

75
NBS-114A (REV, 7-73)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLIC ATION OR REPORT NO. NBS 75-945

2. Gov't Accession

No.

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

The National Measurement System for Surface Properties

5. Publication Date

6. Performing Organization Code

7. AUTHOR(S)

C. J. Powell

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Worlc Unit No. 2320106

11. Contract/Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

Same as above

13. Type of Report & Period Covered

Final

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less (actual summary of most si^iiicant information. If document includes a significant

bibliography or literature survey, mention it here.) An analysis is given of the National Measurement System for Surface Properties.

Emphasis is placed on the properties needed to characterize a solid surface, particularly surface composition, surface atomic structure and surface electronic structure;

these characteristics directly affect many important surface properties or processes

that occur on surfaces (e.g., electrical and optical properties, adhesion, bonding,

catalytic activity, plating, durability, corrosion, decoration, segregation, lubrication and reactivity). The above three forms of surface characterization are widely

utilized in surface-science experiments while measurements of surface composition are routinely made to solve a wide variety of problems in the semiconductor, chemical,

petroleum and metallurgical industries for applications ranging from process and device

development, process control, process evaluation to failure analysis. Surface-characterization measurements in government laboratories support a variety of agency missions. Surface science and surface technology have both grown rapidly in the past ten

years, and further growth is expected. At this time, there is a complete lack of

standards, standard procedures, and standard materials to support surface-characterization measurements. In short, there is no established national system for the measurement of surface properties. Recommendations for NBS action are given to improve and

extend the measurement services required to promote surface science and surface technology and thereby to establish a satisfactory system for the measurement of surface

properties . 17. KEr WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons) National Measurement System for Surface Properties; surface

atomic structure; surface characterization; surface composition; surface electronic

structure; surface properties

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