bluuebunny/crossref_metadata_2025 huggingface dataset:
Multilayer Optics for the Soft X-Ray and Extreme Ultraviolet
Authors: Barbee Troy W.
Published: August 2016

This article considers a particular class of optic microstructure — multilayers for soft x-ray (SXR, 100 eV[124 Å] to 3,000 eV[4.1 Å] and extreme ultraviolet (EUV, 15 eV[800 Å] to 100 eV[124 Å] optics. Multilayers are manmade vapor-deposited depth-periodic layered micro-stractures of high enough quality to be considered synthetic crystals. Layers of two materials, A and B, having significant differences in their scattering powers for x-rays (electron densities) and of uniform thicknesses ta and tb are combined to form a sample of uniform in-depth period d0 ( = ta + tb). These microstructures are of scientific and technological significance since the high angle of incidence SXR and EUV reflectivities of single film reflectors is ~10−4) and since only a limited number of naturally occurring or synthetic large lattice constant materials efficiently diffraction reflect long wavelength radiation (SXR and EUV).

Multilayer microstructure based SXR and EUV optics are direct analogues to standard quarterwave stacks applied at longer wavelengths with the requirement that absorption must be included. They are also analogous to atomic crystalline lattices in that one multilayer period is equivalent to one lattice plane. Thus, the multilayer structure forms a superlattice that diffraction reflects incident radiation. Multilayer diffraction may be modeled using x-ray scattering theory and obeys the refraction-corrected Bragg's law of crystal lattice diffraction. As will be discussed later, many factors determine the character of the multilayer response to an incident spectrum.
Up Close: Center for Advanced Materials Processing at Clarkson University
Authors: Ellis Sonia K. , McNamara Edward P.
Published: August 2016

The Center for Advanced Materials Processing (CAMP) was established in 1985 by Clarkson University in Potsdam, New York. At that time, nearly half of the research at Clarkson was materials-related but was conducted in seven separate departments of science and engineering. To coordinate and encourage this strong materials program, CAMP was created as an interdisciplinary center dedicated to research on high-technology materials processing.

The current corporate sponsors of CAMP are Corning Incorporated, Eastman Kodak, Xerox Corporation, and IBM. These and over 30 other industrial members support individual research projects. In 1987 the New York State Science and Technology Foundation designated CAMP as the New York State Center for Advanced Materials Processing, entitling CAMP to $1 million per year in operating funds. In addition, CAMP is supported by federal and University sources.

In its role as an education and research initiative, CAMP has three goals:

1. Enhance Clarkson University's expertise and reputation as a center of excellence in materials processing research.

2. Greatly increase the mutually beneficial relationships between industrial organizations and the University; and

3. Strengthen graduate and undergraduate education in materials processing.

Innovative research by Egon Matijević, Distinguished University Professor, has contributed greatly to the development of the fundamental principles for the formation and interactions of colloidal dispersions. Using Matijević's work as a foundation, CAMP has developed four programs in high-technology materials research: electronic materials processing, fine-particle processing, particulate control in process equipment, and polymer processing.
Fine Particles: Science and Technology
Authors: Matijević Egon
Published: August 2016

Some readers may wonder about the reasons for having two issues focus on fine particles. Hopefully, this introduction and the articles to follow will offer the necessary justification.

It is fully expected by everybody, professional or laie, that the properties of matter will change if its chemical composition is altered. It is less frequently recognized that many characteristics of materials can be dramatically affected by varying dimensions, yet countless examples in everyday life clearly demonstrate such phenomena. Consider water in droplet form. Driving in rain creates little problem, providing the car has working windshield wipers. In contrast fog, which consists of droplets of much smaller size, represents one of the major hazards in transportation. Obviously, the optical properties of the same matter have greatly altered with diminution. In another example, it is well known that finely dispersed carbon is an excellent adsorbent, a property used in gas masks and in many industries as a purifying agent. Large-sized lumps of such carbon would be useless in these applications.

The effect of particle size on properties of materials can be readily understood from a simple consideration. The total energy of any System, (Etot), consists of two contributions, the internai energy, Ei, and the surface energy, Ei.
Refractories: Something Old and Something New
Authors: Moore Robert E.
Published: August 2016

The earliest refractories for containing melts were quarried from natural deposits of limestone and dolomite. Today these two carbonate rocks serve important roles in the production of metal contact refractories. Early refractories for glass melting on the other hand were manufactured from clays and claystones. These materials are also still used extensively for the batch melting of glasses that are hand formed or blown into art and tableware. Glass contact refractories for the continuous (tank) melting of glass are often fired, cast into large shapes, and arranged in a soldier course which constitutes the sidewalls of the glass tank.

In this brief exposition of refractories technology and allied research, the articles by B. Brezny, T.F. Vazza and T.A. Leitzel, and by T.S. Busby cover materials development, selection, and properties of the systems which have evolved for the efficient melting of steels and glasses. As such they relate to extremes of technological flux in the processes for the manufacture of steel and glass, respectively.

The continuous melting of large volumes of commercial glasses has been carried out in tanks equipped with reverberators for at least 70 years. The basic design of the overall system and of many of the glass fabrication machines for pressing, rolling, and blowing the glass has been constant since World War I. Only the introduction of the float glass method, the famous Pilkington process, for the production of flat glass, has interrupted the slow quiet progress in the technology of continuous glass making.
Interfaces Part I: Structure, Chemistry, Electronic Properties
Authors: Wolf Dieter , Yip Sidney
Published: August 2016

Some of the most important properties of materials in high-technology applications are strongly influenced or even controlled by the presence of solid interfaces. For example, interfaces are the critical element in fiber-reinforced structural ceramics with mechanical properties not even imagined a decade or two ago. The entire electronics industry is based on the fascinating electrical properties of semiconductor interfaces, with ceramic-semiconductor, metal-semiconductor and metal-ceramic interfaces playing critical roles as well. Other examples are surface modification techniques, designed to enhance the corrosion resistance of materials in hostile environments or tailored for tribological or catalytic applications. In contrast to their enormous technological importance, our basic understanding of even the simplest interfaces, such as free surfaces and grain boundaries, is rudimentary at best. It is increasingly recognized, however, that truly significant technological advances can be achieved by a better understanding and control of interfacial processes.

To draw attention to the tremendous opportunites that lie ahead in this lively area of materials research, some recent promising developments in the atomic-level understanding of solid interfaces are highlighted in this issue and in the October issue of the MRS BULLETIN. The theme common to ail the articles in the September and October issues lies in the atomic-level insights that have been gained. While this issue of the BULLETIN focuses on structure, chemistry and some electronic properties of crystalline interfaces, the October issue will be devoted to their mechanical and high-temperature behavior.
Up Close: Materials Science at the CSIRO Division of Applied Physics, Sydney, Australia
Authors: Window Brian
Published: August 2016

The Division of Applied Physics of the Commonwealth Scientific and Industrial Research Organization performs research in the physical sciences to benefit Australian industry and also staffs the National Measurement Laboratory, underpinning the Australian measurement system. CSIRO is the major government-funded research organization in Australia, employing approximately 7,000 people, based in 30 divisions, and whose interests range from the agricultural and livestock areas through prospecting, mining, and manufacturing to information and communication technologies. The general mix of work in the divisions includes a proportion of basic science and a significant involvement in contract research with relevant Australian industries.

The Division of Applied Physics is one of the oldest divisions and celebrates its 50th Jubilee in 1988. This year is also the 200th anniversary of European settlement in Australia and the 25th anniversary of the founding of the Australian Institute of Physics. It was a busy year for the laboratory!

Materials science research in the Division developed from the needs of the standards research program, passed through a period of primarily basic research, and now concentrates on industrial research and the underlying basic research. Four areas which exemplify this progression toward applied research and development are described in this article.

Thin film research started in the Division in the 1950s to produce optical coatings, driven by the requirements of a developing standards research program, and the needs of an astronomy program to study the surface of the sun spectroscopically.
Up Close: The Interuniversity Microelectronics Center (IMEC), Leuven, Belgium
Authors: Denoyelle Dirk
Published: August 2016

The Interuniversity Microelectronics Center, Leuven, Belgium (IMEC) is one of the world's largest independent research centers for microelectronics. It was established in 1984 by the Flemish government as a part of a comprehensive program to promote high technology in Flanders, Belgium. Benefiting from existing experience available mainly at the University of Leuven, IMEC moved into its present facilities in 1986 (Figure 1).

The Center covers a wide range of research topics in the microelectronics domain—VLSI systems design methodologies, advanced semiconductor processing, materials, packaging, and more.

About 50 people work on computer-aided design, developing a series of “true” silicon compilers: CATHEDRAL. With this software, ASIC (application specific integrated circuit) design becomes extremely attractive, since CATHEDRAL covers design from the high system level down to layout.

INVOMEC, the training division of IMEC, supports universities in ASIC design. It trains people for both educational institutes and industry in chip design, makes available the necessary software, and has a well-established Multi Project Chip—Multi Project Wafer service.

The Processing Technologies and Materials Divisions involve about 200 people and have a 3,600 m2 clean room at their disposal. The clean room consists of a 20% class 10 area with a fast-turnaround prototyping line and an 80% class 1000 area.

IMEC's objectives are: to perform research in the microelectronics field, supporting both industry and universities, and to stimulate the microelectronics industry in Flanders.

IMEC performs research on both silicon and III-V technologies.
Microwear Analysis of Prehistoric Stone Tools
Authors: Berry Sarah H. , Bamforth Douglas B.
Published: August 2016

Archaeologists have used microscopes to study traces of use on the edges of prehistoric stone tools for many years, but the past decade has seen a tremendous increase in the technical sophistication and substantive contributions made by this branch of archaeological research. Our purpose is to summarize the basic approaches archaeologists take to microwear analysis, the potentials of these approaches, and the kinds of traces that microwear analysts examine.

Three forms of microwear analysis can be identified and are based on (1) the range of magnification, (2) the type of equipment, and (3) the type of traces examined. The first relies on stereoscopic microscopes, works at magnifications ranging from 10 to 75×, and examines patterns in the abrasion and chipping of tool edges during use. More recent research indicate s that important variation also exists in the way a tool surface is polished during use, and the second analytical approach examines differences in polish appearance as well as utilizing the techniques of the first method. Microwear polishes are visible at magnifications from 100× to 400× using binocular microscopes and incident illumination. Finally, the third approach relies on the scanning electron microscope (SEM) and very high magnifications to identify traces of materials on which the stone tools were used. In this discussion we emphasize the first two of these analytical approaches because very few analysts have used the SEM.
Organometallic Vapor Phase Epitaxy: Features, Problems, New Approaches
Authors: Ghandhi Sorab K. , Bhat Ishwara B.
Published: August 2016

Modern compound semiconductor devices are usually fabricated in one or more layers of single-crystal material, which are epitaxially grown on a crystalline substrate. Since most of these semiconductors decompose into their constituent components at high temperature, epitaxial growth in its simplest form can be accomplished by transporting individual components to a heated substrate, where they react to form the compound semiconductor. This is the basis of molecular beam epitaxy (MBE), where the process is carried out in an ultrahigh vacuum environment.

Growth of these materials in an atmospheric (or reduced pressure) environment is highly advantageous from a commercial point of view. However, this presents a problem, since one of the components usually has a very low vapor pressure. For III-V compounds such as GaAs, AlAs, InAs, and InP, this is the column III component. Consequently, a technique must be provided to transport these elements by means of volatile compounds. This process is known as chemical vapor epitaxy, with halogenic compounds often used as transport agents. One example of this approach is the growth of GaAs from GaCl and AsCl3. During growth, the AsCl3 is made to prereact with gallium to form volatile GaCl, which is stable at elevated temperatures and can be transported to the substrate. High quality GaAs can be made by this process, and it is widely used for making a number of GaAs devices.
Theoretical Modeling of Czochralski Crystal Growth
Authors: Derby Jeffrey J.
Published: August 2016

The growth of single crystals with precisely controlled properties is one of the most demanding goals of modern materials processing, and its realization depends on the application of fundamentals from solid-state physics, chemistry, thermodynamics, and transport phenomena. Bulk semiconductor substrates and many high-power solid-state laser host materials are typically produced by solidification from the melt. The quality of the crystals produced this way hinges on process conditions which are predominantly determined by the transport of heat, mass, and momentum in the melt and crystal. Accurate modeling of melt crystal growth promises to enhance our understanding of existing systems and improve the design and control of future processes, thereby accelerating the development of advanced materials and devices.

Theoretical modeling is often the only way to probe the complex interactions which characterize melt crystal growth, especially the effects of process changes on internal features of growth that cannot be directly measured on-line, such as the shape of the melt/crystal interface or temperature gradients within the growing crystal. In this way, computer simulation can serve as a design tool for developing control strategies and process innovations. Further, modeling serves as a test-bed for theoretical experiments which extend our knowledge of how fundamental physical phenomena govern the process.

This report attempts to provide a glimpse of how analysis and modeling have impacted the understanding of Czochralski (CZ) crystal growth. The reader is referred to several excellent reviews for more in-depth information regarding melt crystal growth modeling.
Optical-Guided-Wave Modulators
Authors: Becker R.A.
Published: August 2016

Planar optical-guided-wave devices have been in existence for over 20 years. Two interesting, informative articles can be found in References 1 and 2. Much of the early work in guided-wave optics was on passive devices, but this was also when much of the theoretical understanding of optical-guided-wave (OGW) devices was developed. This theoretical understanding applies to active devices as well. It's interesting to note that the commercialization of passive, glass-based guided-wave devices has just occurred with product introductions by Corning & Nippon Sheet Glass. Active OGW devices (i.e., ones where the light properties can be altered with an applied voltage) have been reported since about 1975. In 1985, Crystal Technology, Inc. announced the first commercially available product—a high-speed, efficient, intensity modulator. Throughout the ten years in between, a huge amount of technical literature has been generated. Most of the work has centered on the Ti:LiNbO3 waveguide technology although several other material systems have been demonstrated as well.

Materials upon which optical-guided-wave modulators have been fabricated include: dielectrics such as lithium niobate (LiNbO3), lithium tantalate (LiTaO3), and potassium titanyl phosphate (KTP); the III-V semiconductor compounds, gallium arsenide (GaAs) and indium phosphide (InP); and a variety of organic polymers. Of these materials, waveguides on LiNbO3 are clearly the most developed and are offered for sale commercially. For this reason I will concentrate on this material system while making comparisons to the other material systems when appropriate.
Characterization of Materials by Thermoanalytical Techniques
Authors: Gallagher P.K.
Published: August 2016

The generally accepted definition for thermal analysis is that it covers “a group of techniques in which a physical property for a substance and/or its reaction product(s) is measured as a function of temperature while the substance is subjected to a controlled temperature program.” From this broad scope, it is evident that at some point in their careers nearly all experimental materials scientists have been practicing thermal analysts. It is also obvious that the techniques of thermal analysis are applicable to the entire range of materials. Consequently, it is difficult, it not impossible, to properly review such a topic in several pages, but I hope that a carefully selected handful of examples will acquaint the readers with the standard techniques and the enormous versatility inherent in thermal methods. One aspect which simplifies the review is that the methods are conceptionally very simple and do not require extensive descriptions.

Table I describes some of the more common techniques for which examples will be presented. Obviously, many more properties have been studied; however, those listed will suffice as an introduction to the subject.

Because all information derived from thermal methods frequently has only an indirect correlation with the chemical concentration or process of interest, it is important to use more than one technique where possible.
Rapidly Solidified Neodymium-Iron-Boron Magnets
Authors: Croat J.J. , Herbst J.F.
Published: August 2016

Permanent magnets have long occupied an important position in technology. Among the multitude of products using permanent magnets are televisions, telephones, computers, videocassette recorders, audio systems, household appliances, and perhaps surprisingly to many consumers, automobiles. Figure 1 illustrates the numerous magnet applications in a modern passenger vehicle. These applications include an array of dc electric motors such as the starter, heater and air conditioner blower, windshield wiper, window lift, door lock, and fuel pump motors. A fully equipped car can have more than 30 dc electric motors. Other uses include actuators, gauges, and sensors. In all these examples higher performance magnetic materials may afford the advantages of increased operating efficiency and reduction in size and weight.

One performance index or figure of merit for a permanent magnet is the energy product (BH)max, the maximum product of magnetic induction B and applied field H in the second quadrant of the B-H hysteresis curve. The so-called theoretical (BH)max, the highest energy product realizable in principle, is simply given by (4πMs)2/4, where Ms is the saturation magnetization. Progress in the development of technologically significant hard magnets has been monitored generally by improvements in (BH)max. For many years three types of materials were of commercial importance, namely, alnico, ferrite, and samarium-cobalt alloys based on either the SmCo5 or Sm2Co17 intermetallic compounds. Of these the Sm-Co magnets offer the largest energy products, on the order of 20 MGOe.
Ultrasonic Characterization of Texture and Formability
Authors: Clark Alfred V.
Published: August 2016

There are now theories which predict the effect of texture on elastic properties and hence on the velocities of bulk, surface, and guided ultrasonic waves. Furthermore, there is a relation between texture and formability. These relationships can be potentially exploited to make ultrasonic measurements of formability, and partial pole figures can be made with ultrasonic techniques.

This article presents results of various ultrasonic measurements made to characterize the formability of rolled steel and aluminum alloy sheet. A good correlation generally exists between ultrasonic velocity measurements and formability. Furthermore, there is a good possibility of on-line formability measurement using a noncontacting ultrasonic transducer.

The influence of texture on material properties has been long recognized, and several excellent texts have been wholly or partly devoted to the subject. Texture classically has been measured with either x-rays or neutron diffraction. Lately, there has been interest in characterizing texture with ultrasound (high-frequency sound) as well.

Ultrasound has several potential advantages over x-ray and neutron diffraction techniques. Ultrasonic systems are nondestructive, can rapidly scan large volumes of material, require no radiation sources, and can be devised to measure either surface or bulk textures. There is a distinct possibility that ultrasonic texture monitoring can be implemented in real-time in a production environment such as a rolling mill.
Ultrasonic NDE for Surface Roughness
Authors: Eitzen D.G. , Blessing G.V.
Published: August 2016

In a number of materials processes, on-line monitoring of surface finish is important to control material quality or process integrity. In rolling some sheet steel into coils, the rollers are intentionally roughened so that a specified roughness range is transferred to the sheet. Then the end product sheet can be optimally spray painted. The rollers, however, eventually wear smooth. Currently, pieces of sheet are sampled by hand and if a piece is too smooth, the coils produced since the last good sample are problematical. In automated machining it is useful to know during the cutting process whether the part will have the required surface finish. More importantly, for a large class of automated machining applications, a dull tool can be defined as one which produces a rougher part surface.

Monitoring the finish of the newly cut surface could allow a decision to be made about changing the tool. For untended machining this could provide a strategy for tool management. The strategy would be much more efficient than the alternative of changing a tool after X hours when it might have lasted 10X hours were it in the upper 10% of the life curve.

To fulfill the need for noncontact surface finish measurement, optical scattering devices have been developed to provide a surface interrogation technique. However, this technique is significantly limited for many applications because the optical beam must interact with a dry surface. This makes its application very difficult in the harsh wet environment encountered in automated machining and in some metal sheet production.
Preview: 1988 MRS Spring Meeting: Bally's ∎ Reno, Nevada Events Scheduled April 4-10
Authors: Clark David E. , Draper Clifton W. , Liu C.T.
Published: August 2016

The 1988 Spring Meeting of the Materials Research Society will be held at Bally's in Reno, Nevada, with events spanning April 4-10. Program Chairs David Clark, Clif Draper, and Chain T. Liu have planned the most diversified topical symposia coverage to date. In addition to a thorough examination of the popular and “hot news” areas, the meeting will also offer a selection of intriguing specialty topics never before offered at an MRS meeting. This year's Spring meeting will feature 16 topical symposia, a program of 23 short courses, and an equipment show. Highlights of the symposia are described below. The names of the short courses and equipment exhibitors are listed elsewhere in this issue. For details see the 1988 MRS Spring Meeting Preliminary Program mailed to all MRS members.

During the Plenary and Student Awards session, Raymond D. Tuminaro of AT&T Bell Laboratories will present the Plenary Address on “Materials Aspects of the SL Undersea Optical Cable Design.” Tuminaro will focus on the fiber and cable materials, review their vulnerabilities to degradation mechanisms, and explore methods currently being used to assure acceptable performance levels for the projected 25-year service life of these systems.

A special feature is being planned for the 1988 MRS Spring Meeting. A major photomicrography exhibition—Microscapes: The Hidden Art of High Technology—will focus on the seldom-seen world of advanced developments in microelectronics and lightwave communications.
Up Close: Institut Max von Laue-Paul Langevin, An International Neutron Research Center
Authors: Maier Bernd P.
Published: August 2016

The Institut Max von Laue-Paul Langevin (ILL) at Grenoble, France was formally founded in January 1967, with the signature of an intergovernmental convention between France and the Federal Republic of Germany. The aim was to provide the scientific community of the affiliated countries with a unique neutron beam facility applicable in fields such as the physics of condensed matter, chemistry, biology, nuclear physics, and materials science. The construction of the Institut and its high flux reactor was undertaken as a joint French-German project, with a total capital investment of 335 million French francs.

The reactor first went critical in August 1971 and reached its full power of 57 MW for the first time in December 1971. The year 1972 saw the startup of the cold and hot sources, the first instruments, and the beginning of the experimental program.

On January 1, 1973, the United Kingdom joined the Institut as a third equal partner, contributing its share to the total capital investment. In December 1986, an agreement on “Scientific Membership” for Spain was signed for a period of five years starting January 1, 1987. The ILL is a nontrading company under French civil law. The three countries are represented by the following associates: Kernforschungszentrum Karlsruhe GmbH (W. Germany), Centre National de la Recherche Scientifique (France), Commissariat
à l'Energie Atomique (France), and Science and Engineering Research Council (United Kingdom). These associates are represented on a Steering Committee which establishes the general rules of the management of the ILL.
Continuous Production of Narrow Size Distribution Sol-Gel Ceramic Powders
Authors: Ring Terry A.
Published: August 2016

In the early 1980s Prof. Bowen at Massachusetts Institute of Technology advanced the concept that sintered ceramic bodies could be improved by decreasing the defects in green bodies. In addition, his group advanced the idea that ideal green bodies should be composed of monodisperse particles packed into an ordered array. They used the hydrolysis of metal alkoxides to produce narrow size distribution sol-gel powders (i.e., amorphous). These powders were allowed to settle under the force of gravity into an ordered array which was dried and sintered. Sintering took place at much lower temperatures and at faster rates than traditional ceramic processing (e.g., broad size distributions of crystalline powders). Improvements in strength and toughness of the sintered body were never demonstrated by Bowen's group for these novel ceramics.

Ordered particles have packing faults which lead to ordered domains, as shown in Figure 1, similar to grains in polycrystalline materials. When sintered, the ordered domains shrink separately and pull away from each other as shown in Figure 2. This leads to defects in the sintered body of sizes similar to those of the ordered domains which can encompass as many as 10,000 particles. These ordered domains lead to weakness in the sintered body according to Griffith's theory.
Electronic Ceramic Thin Films: Trends in Research and Development
Authors: Tuttle Bruce A.
Published: August 2016

Electronic ceramic materials research is one of the fastest growing, most highly publicized areas of materials science. Subjects receiving considerable attention include high temperature superconductors, multilayer ceramic composites for high density microelectronics packaging, and ferroelectric electro-optic thin films. A complete review of all aspects of electronic ceramics research is beyond the scope of this article, which will focus on two general topics whose development is representative of recent contributions to the field. These two areas are synthesis and characterization of electronic ceramic films,1 and controlled use of low level dopants (1,000 ppm or less) in bulk polycrystalline ceramics, thin films, and single crystals to achieve desired properties. Perspective of the progress in ceramic film development is given by a review of single-crystal synthesis and properties.

Several examples of the impact that low level dopants and thin film synthesis have on electronic ceramics development are presented. Dopant concentrations of 1,000 ppm or less can have a dramatic effect on microstructural, optical, and electrical properties. For example, a decrease in aluminum content of 150 ppm resulted in an increase in grain size from 1 to 25 microns in otherwise identical ZnO varistors. Background aluminum concentrations for these varistors were less than 10 ppm. In another example, the photorefractive effect, the change in refractive index with optical light intensity, has been shown to be altered by orders of magnitude with ppm doping levels in ferroelectric electro-optic materials.

Several electronic ceramic devices have recently been developed due to improvements in ceramic film processing. Examples of these devices include: 1. multilayer PZT transformers, which allow fabrication of complex monolithic passive multicom-ponent networks, 2. liquid cooled multilayer ceramic substrates, with 400×800 micron liquid transfer capillaries integrated into the multilayer structure via ceramic processing techniques for high density VLSI packaging, and 3. ferroelectric electrooptic thin films that are compatible with silicon or III-V technology. For all the above applications, synthesis of electronic ceramic materials into high purity films is essential.
Techniques for Materials Microanalysis
Authors: Helms C.R.
Published: August 2016

The science and technology of ultrasmall three-dimensional materials systems has been developing rapidly the last 20 years or so. Catalysts, coatings, composites, as well as electronic device structures—all rely on materials properties on an atomic scale. To develop such new materials and understand the chemical and physical properties that determine their unique behavior, we also require analytical tools with atomic level spatial resolution and at the same time the desired measurement capability. This need, along with extensive scientific interest in the fundamental chemical and physical properties of free surfaces, has led to the continued development of microanalytical chemical analysis techniques over the past 20 years. Most readers will be familiar with many of these techniques with acronyms such as AES, XPS, RBS, SIMS, ESCA, etc. This issue of the MRS BULLETIN will review some recent advances in the development of these techniques as well as introduce new techniques with significant advantages over the older ones.

As you can see from the thickness of this issue, it is difficult to cover the entire field in a finite amount of space. This led us to limit the discussion to those microanalytical tools which can easily be applied to the analysis of buried interface structures such as those found in semiconductor devices.
Materials Analysis with High Energy Ion Beams Part I: Rutherford Backscattering
Authors: Gossmann H-J. , Feldman L.C.
Published: August 2016

This article discusses the underlying principles of Rutherford backscattering spectrometry (RBS). Consideration of the theory of the interaction of high energy ions with solids leads to the conclusion that quantitative elemental analysis of the near-surface composition of solids can be performed by RBS. Examples are given.
Fundamentals of Sputtered Neutral Mass Spectrometry
Authors: Kaiser U. , Huneke J.C.
Published: August 2016

Sputtered neutral mass spectrometry (SNMS) is a technique for elemental and isotopic analysis with excellent detection limits, with similar sensitivity for all elements and without substantial matrix effects. Particles sputter atomized from the sample surface are ionized and mass spectrometrically measured. Elemental detection limits are routinely 1–10 ppm, but can be as low as 1–10 ppb. Particular modes of SNMS enable the measurement of accurate concentration depth profiles with resolutions approaching 20 Å and the measurement of electrically insulating samples.
Surface Analysis by Laser Ionization
Authors: Pallix J.B. , Becker C.H. , Newman N.
Published: August 2016

An overview is presented of a recently developed surface analysis method that combines (1) desorption of neutral atoms and molecules from a sample, typically by sputtering, (2) efficient uniform ionization close to but above the surface by an intense ultraviolet laser beam, and (3) time-of-flight mass spectrometry. This technique, surface analysis by laser ionization, or SALI, provides extremely efficient and sensitive quantitative analysis of surfaces and materials with high depth resolution. Essentially any type of material can be analyzed as evidenced by the examples presented here: the Au-GaAs system, a phosphor-silicate glass, and a bulk polymer.
Advances in Small Spot ESCA
Authors: Bryson Charles E. , Chaney Robert E.
Published: August 2016

The changes in Electron Spectroscopy for Chemical Analysis (ESCA) equipment since 1982 have significantly expanded the range of applications and general utility of the technique. Most of these changes center around improvements in spatial resolution although there have also been improvements in speed and energy resolution. The implications of these changes extend beyond the obvious ability to obtain information from small features on samples.

The three major approaches to controlling spatial resolution are: (1) defined area x-ray sources, (2) limited field-of-view electron analyzers, and (3) imaging electron analyzers. Each of these will be reviewed briefly and their salient features contrasted. These advances in the instrumentation have brought about the following benefits to users of the ESCA technique: (1) ability to analyze small features, (2) rapid depth profiling, (3) multiple samples, and (4) improved charging control. Examples are included.
Advances In Analytical Auger Electron Spectroscopy
Authors: Chang Chuan C.
Published: August 2016

Fundamental principles and experimental procedures for fully utilizing the power of Auger analysis are discussed. Topics include: quantitative analysis, high resolution imaging, depth profiling, and noise reduction. These studies reveal several improvements that might be expected in the immediate future and how they might be achieved. Some knowledge of Auger spectroscopy is assumed, but references on theory, principles, instrumentation, and applications are cited.
Silica Glasses
Authors: Griscom David L.
Published: August 2016

Fifty years ago, who could have imagined that silicon dioxide—the material of ordinary beach sand—would become one of the most important materials of present-day optics and electronics? Yet SiO2is arguably the most crucial material component in current-generation fiber optics and metal-oxide-semiconductor (MOS) device technology. In MOS field-effect transistors (MOSFETs), SiO2serves not only as the gate insulator, but also as the “field oxide” (which isolates various components of an integrated circuit) and as the packaging material which seals the device from outside contamination. In these roles silica acts as a “perfect dielectric,” being characterized by an essentially infinite resistivity (actually ~1016Ohm · m at 300 K). The ability to form such a high quality dielectric film with a near-perfect lattice match on single-crystal silicon continues to favor silicon-based MOS technology over technologies founded on electrically superior GaAs.

In the rapidly developing fiber optic arena, fused silica is still “king” due to a combination of properties, including extremely high transparency over a range of usable wavelengths (Figure 1), low material dispersion (~0 at 1.3/üm), high tensile strength (~ 150 kpsi), and high chemical durability. In addition, bulk forms of silica continue to find application in lenses, prisms, windows, and low-coefficient-of-thermal-expansion reflective optics; thin silica films are common components of the highly reflective and anti-reflective surface coatings which are laid down on reflective and transmissive optics, respectively.
Assessment of Directions and Opportunities in Current and Future Materials Education
Authors: Bernstein I.M.
Published: August 2016

There is considerable excitement and some turmoil in undergraduate and graduate education in the broad field of materials, as well as in its subfields of metallurgy, ceramics, and polymers. While the reasons are many, the underlying driver is the growth in the visibility and diversity of a young field evolving rapidly into a true discipline, much like chemical engineering and biology from their early roots mainly in chemistry.

The University Materials Council (UMC), the group representing accredited materials departments has had a longstanding, obvious interest in education and has been actively involved in assessing current and future directions. More recently, a comprehensive study under the auspices of the National Research Council (the Materials Science and Engineering Study), has been undertaken to develop a unified view of recent progress and new directions in materials science and engineering (MSE), and to assess future opportunities and needs. As part of this ambitious endeavor, a panel on education (Panel 5) was established with the following charges:

• To investigate and document existing human resources in MSE;

• To identify future directions of education in MSE, including education in and out of materials departments;

• To identify needs and opportunities for increasing interdisciplinarity in MSE; and

• To identify needs and opportunities in lifelong education.
Specific Materials Science and Engineering Education
Authors: Readey D.W.
Published: August 2016

Forty years ago there were essentially no academic departments with titles of “Materials Science” or “Materials Engineering.” There were, of course, many materials departments. They were called “Metallurgy,” “Metallurgical Engineering,” “Mining and Metallurgy,” and other permutations and combinations. There were also a small number of “Ceramic” or “Ceramic Engineering” departments. Essentially none included “polymers.” Over the years titles have evolved via a route that frequently followed “Mining and Metallurgy,” to “Metallurgical Engineering,” to “Materials Science and Metallurgical Engineering,” and finally to “Materials Science and Engineering.” The evolution was driven by recognition of the commonality of material structure-property correlations and the concomitant broadening of faculty interests to include other materials. However, the issue is not department titles but whether a single degree option in materials science and engineering best serves the needs of students.

Few proponents of materials science and engineering dispute the necessity for understanding the relationships between processing (including synthesis), structure, and properties (including performance) of materials. However, can a single BS degree in materials science and engineering provide the background in these relationships for all materials and satisfy the entire market now served by several different materials degrees?

The issue is not whether “Materials Science and Engineering” departments or some other academic grouping of individuals with common interests should or should not exist.
Metallic Superlattices: The Study of Materials at Length Scales From a Few to Hundreds of Angstroms
Authors: Schuller Ivan K. , Homma H.
Published: August 2016

We present the possibilities that metallic superlattices offer for the study of materials at length scales ranging from a few to hundreds of angstroms. The materials problems being studied span practically all interesting solid-state phenomena, including superconductivity, magnetism, elastic behavior, development of novel materials, diffusion, ion beam mixing, crystallization, and amorphization. Several applications are also being pursued. We present a few examples of problems that can be studied at different length scales. Emphasis is made that for a proper study of materials properties, extensive structural characterization is imperative.
Ion Beam Processing
Authors: White C.W.
Published: August 2016

Ion beams are used extensively in materials research for processing and synthesis as well as for characterization. In the last few years, enormous advances have been made regarding the use of ion beams for processing or synthesis, and this issue of the MRS BULLETIN will review some of those advances. (The use of ion beams for materials characterization will be the subject of a future issue of the BULLETIN.) The areas covered in this issue are ion implantation, ion beam mixing, ion-assisted deposition, and direct ion beam deposition. For each area, recognized experts in the field prepared overview articles that should be very interesting to those who are not active in the field, and that should be useful to other experts in the field.

The first large-scale use of ion beams for materials modification took place in the semiconductor industry more than 20 years ago when ion implantation began to be used to dope the near-surface region of silicon with Group III or Group V dopants. The use of ion implantation in the semiconductor industry has undergone explosive growth, and today almost all electronic devices are fabricated utilizing at lest one ion implantation step.

In addition to the semiconductor area, research is being carried out using ion implantation in a multitude of other areas which include ceramics, metals and alloys, insulators, etc. The article on “Ion Implantation” by S.T. Picraux and P.S. Peercy provides an excellent overview of current research activities involving ion implantation of a wide spectrum of materials.
Up Close: The Advanced Materials Institute
Authors: Morse Jerome G.
Published: August 2016

The Advanced Materials Institute (AMI) is the materials research arm of the Colorado Advanced Technology Institute (CATI), a state agency created in 1983 by the state General Assembly as an economic development initiative involving academic, industry, and government sectors. AMI represents a unique process in academic research: long-term materials needs of industry members are addressed by university investigators, with federal agencies providing the major source of funding.

AMI is a consortium of four research universities (Colorado School of Mines as the lead institution, Colorado State University, and the Universities of Colorado and Denver) and a present industrial membership of nine corporations (AMAX Inc., Adolph Coors Company, Digital Equipment Corporation, Gates Company, Hewlett Packard, IBM, Manville, Martin Marietta, and Telectronics). The Institute is governed by a Board of Directors with representatives from each participating organization. Sustaining memberships, which do not include representation on the Board, are available; memberships of both kinds are open to non-Colorado-based companies.

The long-term materials needs of industry members provide AMI's research agenda; many items, once identified, become company-shared interests. Requests for proposals, based on the agenda, are distributed to the affiliated universities for competitive awarding of seed funds. Proposals receive peer review and the Board selects those to be funded.
New Opportunities in Materials Research With Pulsed Neutrons
Authors: Lander G. H.
Published: August 2016

Neutrons have played an important role in materials research for the last 30 years. Recently a new method of producing neutrons, with proton accelerators and specifically designed targets and moderators, has been developed. Many of the techniques developed with these powerful spallation sources open new opportunities for materials research, some of which will be covered in this article. An effort will be made to explain the types of science that can be done, rather than details of the techniques. Spallation sources are being operated as user facilities so the inexperienced can count on expert assistance.
Current limitation after pinch-off in AlGaN/GaN FETs
Authors: Dietrich R. , Wieszt A. , Vescan A. , Leier H. , Redwing Joan M. , Boutros Karim S. , Kornitzer K. , Freitag R. , Ebner T. , Thonke K.
Published: August 2016

Piezoelectric AlGaN/GaN FETs on SiC with high carrier mobility have been fabricated yielding IDS=450 mA/mm and gm=200 mS/mm. In the on-state, under UV-illumination, the devices sustain a drain voltage of VDS=49 V, corresponding to a power dissipation of 26.5 W/mm. On turn-on of the device from the pinch-off state, a significant delay in the drain current build-up is observed. This effect depends on the pinch-off time and the pinch-off voltage and can be removed by either a brief UV-illumination or a VDS>25 V applied in the on-state. The drain current transients are characterized by a relaxation time τ, which is in the order of several hundred seconds. From the temperature dependence of τ, an activation energy of about 280 meV and a capture cross section of 4.4·10−18cm2 were determined. The devices show pronounced persistent photoconductivity (PPC) and the drain current ID is sensitive to illumination.