bluuebunny/crossref_metadata_2025 huggingface dataset:
673K Embrittlement of Ferritic Spheroidal Graphite Cast Iron
Authors: Yanagisawa O. , Lui T. S.
Published: March 2011

Intergranular fracture had been observed in the temperature range from 573K – 673K, where the ductilit miniTum appears at 673K for the strain rate of sec−1 in ferritic spheroidal graphite cast irons.

The cause of intergranular fracture at about 673K has been investigated. The following two points are emphasized. The first is the role of hydrostatic tensile stress in triaxial stress field developed in ferrite matrix among graphite nodules, relating to the effect of graphite volume fraction on the intergranular fracture. The second is the role of carbide precipitation during dynamic strain ageing, relating to the strain rate and the temperature dependence of the intergranular fracture.
Heat Treatments of Chromium-Manganese White Cast Irons for an Optimum Combination of Wear Resistance and Impact Strength
Authors: Basak A. , Penning J. , Dilewijns J.
Published: March 2011

As cast microstructures of chromium-manganese white cast iron containing about 2.5 % carbon, 0.7 % silicon, 4.5 % manganese and 11.5 % chromium reveal discontinuous plate like eutectic carbides embedded in a mainly austenitic matrix[1](Fig.1). This austenitic matrix accounts for a higher impact strength and a lower wear resistance. It has been reported elsewhere [2] that a martensitic matrix containing uniformly distributed fine alloy carbides exhibits a very good wear resistance, but lower impact strength.
Graphite Inoculants For Gray Cast Iron
Authors: Loper C. R. , Shirvani S. , Witter T. H.
Published: March 2011

The ability of graphitic materials to serve as inoculants during the solidification of flake graphite cast irons has been examined and related to the physical structure of these materials. Carbon dissolution in cast iron melts is reviewed relative to dissolution rates and carbon recovery obtained from a variety of materials. Maximum dissolution rates and carbon recovery are shown to be attained with high purity carbon products, where the ash present does not form a network structure as carbon enters solution, and where the sulfur content of the carbon product is low.

Successful inoculation requires that the carbon product be graphitic, or possess a high degree of graphiticity, and that the solution rate be controlled so that the substrate graphite is present in the molten iron at the time of graphite formation during solidification. The characteristics of inoculants whereby this controlled solution rate can be achieved are discussed.

Inoculation with graphitic materials is shown to be effective in flake graphite cast irons, but is not effective in spheroidal or compacted/vermicular graphite cast irons. Factors contributing to this effect are discussed.
Time-Resolved Studies of Rapid Solidification in Highly
Undercooled Molten Silicon
Authors: Lowndes D.H. , Jellison G.E. , Wood R.F. , Pennycook S.J. , Carpenter R.W.
Published: March 2011

A KrF (248 nm) pulsed laser was used to melt 90-, 190-, and 440-nm thick
amorphous silicon layers produced by Si ion implantation into (100)
crystalline Si substrates. Time-resolved reflectivity measurements at two
different probe wavelengths (633 nm and 1.15 μm) and post-irradiation TEM
measurements were used to study the formation of an undercooled liquid Si
phase and the subsequent solidification processes. The time-resolved
measurements provide new experimental information about the nucleation of
fine-grained Si crystallites in undercooled liquid Si, at low laser energy
densities (Eℓ), and about the growth of large-grained Si in the
near-surface region at higher Eℓ. Measurements with the infrared
probe beam reveal the presence of a buried, propagating liquid layer at low
??. Model calculations indicate that this liquid layer is generated in part
by the release of latent heat associated with the nucleation and growth
process.
Relation Between Temperature and Solidification Velocity in
Rapidly Cooled Liquid Silicon
Authors: Thompson M. O. , Bucksbaum P. H. , Bokor J.
Published: March 2011

A semi-empirical method to determine the undercooling-velocity relationship
for laser induced melting is presented. The technique uses measurements of
melt depth versus time to control numerical simulations, resulting in a map
of the interface temperature as a function of time, and consequently as a
function of the interface velocity. The results are independent of any model
for the velocity-undercooling relationship. Results of the technique on
simulated and experimental melt depth data are presented. Transient
conductance data on 28 nanosecond 694 nm laser irradiation of silicon
indicate an undercooling-velocity slope of 17±3 K/(m/sec) near the melting
point. Picosecond optical transmission data show a much smaller slope.
Laser-Induced Surface Ripples: What is Understood and What is
Not
Authors: Fauchet P.M. , Siegman A.E.
Published: March 2011

The most predominant ripple properties can be explained by existing
perturbative theories. We present experimental results on novel types of
ripples, which suggest that theory has to go beyond first-order perturbation
and that the material's response is not well understood.
Laser Irradiation of Ge(100): An Assessment of Surface Order
with He Diffraction
Authors: Lambert W. R. , Trevor P. L. , Schulberg M. T. , Cardillo M. J. , Tully J. C.
Published: March 2011

We investigate the effects of Nd:YAG and excimer laser irradiation on the
Ge(100) surface under UHV conditions over a temperature range 140 < T(K)
< 300 using the surface sensitive probe of He atom diffraction. We study
the effects of irradiation on surface damage and order using the apparent
(2×1) ࢐ c(2×4) transition. We monitor surface contamination in situ. The
temporal thermal response is modeled theoretically to aid in assessing the
experimental results. The capability to maintain a Ge(100) surface at low
temperatures free of contamination and well ordered is demonstrated.
Electric Conductivity of Vitreous Silica during Pulsed-Electron-Beam Irradiation
Authors: Stern Stanley H. , Fiorito Ralph B.
Published: March 2011

We describe a measurement of the transient conductivity induced in amorphous SiO2during irradiation by an intense and energetic electron beam. Preliminary results of an experiment [1] we performed at the Pulsed High - Energy Radiographic Machine Emitting X Rays (PHERMEX) facility of Los Alamos National Laboratory indicate that a beam of electrons of energy 17.5 MeV, of current density 1 kA/cm2, and of micropulse duration 3 nsec induce in a-SiO2an electric conductivity 007E 6 × 10-3(03A9-cm)-1. This value is 15 orders of magnitude larger than the ordinary (ionic) conductivity of the material [2].
Kinetics and Mechanisms of Solid Phase Epitaxy and Competitive
Processes in Silicon
Authors: Olson G.L.
Published: March 2011

Recent progress in studies of temperature dependent kinetic competition
during solid phase crystallization of silicon is reviewed. Specific areas
which are emphasized include: the enhancement of solid phase epitaxial
growth rates by impurity-induced changes in electronic properties at the
crystal/amorphous interface, the influence of impurity diffusion and
precipitation in amorphous silicon on the kinetics of epitaxial growth, the
effects of impurities on the kinetic competition between solid phase epitaxy
and random crystallization, and the kinetics of solid phase crystallization
at very high temperatures in silicon.
Explosive Crystallization in A-Ge Films Irradiated with
Microsecond Laser Pulses
Authors: Sharma R.K. , Bansal S.K.
Published: March 2011

Explosive crystallisation has been observed in deposited a-Ge films
irradiated with pulsed Nd-glass laser beam of 400 micro second duration.
Transmission electron microscopic examination of the irradiated film shows a
polycrystalline region surrounded by radial dendrites of ~ 8-10 ;Cm size.
Analysis of the results is consistent with the duplex-melting model of the
explosive crystallisation mechanism. Heat released during the amorphous to
crystalline transformation of a localised region abruptly crystallises the
surrounding area resulting in dendritic growth. The crystallisation is
self-sustaining untill the temperature ahead of liquid/amorphous interface
drops below 775 K. These results are consistent with earlier study of
explosive crystallisation in unsupported a-Ge films and further confirm that
the heat loss to the underlying substrate governs the dynamics of the
crystallisation process.
Dynamic Annealing Phenomena and the Origin of RTA-Induced
“Hairpin” Dislocations
Authors: Maszara W. , Sadana D.K. , Rozgonyi G.A. , Sands T. , Washburn J. , Wortman J.J.
Published: March 2011

The geometry, origin, and diffusion along hairpin defects in Si were
investigated using TEM and SIMS techniques. The defect that grows from the
amorphous-crystalline (a/c) interface following solid phase epitaxy growth
front was found to be a perfect dislocation with a/2(101) Burgers vector.
Misoriented microcrystallites within the a/c transition region are proposed
to be nucleation sites for the hairpin dislocations. The density of the
crystallites increases with an overall coarsening of the interface which
occurs during dynamic annealing processes stimulated by implantation or
post-implantation low temperature annealing. Hairpin dislocations were found
to pipe-diffuse boron at much higher rates than bulk processes significantly
shifting dopant profiles. The diffusion coefficient of boron pipe diffusion
at 1150°C was found to be about 104 times higher than the bulk
one.
A Comparison of Deep Levels Generated In InP by Proton and
Deuteron Bombardment
Authors: Macrander A. T. , Schwartz B.
Published: March 2011

A predominant deep level which has an activation energy of 0.4 eV was found
to have been formed in the region between the surface and the end-of-range
of 200 keV ions. In the fluence range 1012 −
1013cm−2 essentially no difference between the deep
level spectra for proton and deuteron bombardments was found.
Rapid Thermal Annealing in Si
Authors: Seidel T.E. , Pai C.S. , Lischner D.J. , Maher D.M. , Knoell R.V. , Williams J.S. , Penumalli B.R. , Jacobson D.C.
Published: March 2011

Certain aspects of Rapid Thermal Annealing (RTA) are reviewed. Temperature
considerations are discussed. The implant disorder removal rate is measured
(5eV removal energy for As induced damage). Shallower defect-free junctions
are obtained using RTA. Results of a ”Round Robin”-RTA annealing are
presented, transient enhanced diffusion is not prominent for As. New results
for the concentration enhanced diffusion of As are presented. Diffusion from
the channeling-tai1 region of shallow boron diffusions is noted as a
limiting factor for producing shallow p+-junctions. Other issues
are briefly discussed.
Rapid Thermal Annealing of Pre-Amorphized B and
BF2-Implanted Silicon
Authors: Calder I.D. , Naguib H.M. , Houghton D. , Shepherd F.R.
Published: March 2011

Shallow p+n junctions have been formed through a combination of
pre-amorphization of the silicon surface by implantation of 28Si,
33Ar, or 73Ge, low energy implantation of boron or
BF2+, and rapid thermal annealing (RTA) in a tunqsten halogen lamp
system. Both pre-amorphization and RTA are required to form a shallow
(<0.25 μm) junction, for either boron or BF2+. Arqon pre-amorphization results in poor electrical activation
of the boron, while germanium gives the lowest sheet resistivity, but is
responsible for a deep boron tail during implantation. The residual damage
is characterized by a plane of dislocation loops centred either close to the
boron concentration peak, for B+ implantation into a crystalline
substrate, or at the original amorphous-crystalline interface, for
pre-amorphized specimens.
Light-Induced, Short-Time Annealing of Silicon-Implanted
Layers
Authors: Wouters D. , Maes H.E.
Published: March 2011

Short time anneal experiments were performed in a specially developed
annealing system based on a bank of Tungsten-Halogen lamps. The annealing
process during the temperature transient was studied as a function of the
illumination time with the system operating in the constant maximum power
regime. By using this procedure it was shown that electrical activation of
all elements (B, P, As) considered in this study is completed within the
transient period without noticeable diffusion. Redistribution of the
implanted profiles was only observed for longer times after the steady state
temperature was reached. Pre-amorphization with Argon is found to
significantly alter and retard the annealing behaviour.
Formation of Shallow P+ Junctions Using Two-Step
Anneals
Authors: Drowley C.I. , Adkisson J. , Peters D. , Chiang S.-Y.
Published: March 2011

Shallow (0.15-0.2 μm deep) p+ junctions have been formed using boron
implanted into silicon which was pre-amorphized using a silicon implant. The
implants were annealed using a two-step process; initially the wafers were
furnace annealed at 600 °C for 100 min., followed by a rapid isothermal
anneal (RIA) at 950-1100 °C for 10 sec. For comparison, some wafers were
only given a single-step rapid isothermal anneal at 950-1100 °C for 10 sec.
The shallowest junctions were formed when the amorphous silicon layer was
deeper than the boron implant, because of the suppression of channelling.
When the amorphous/crystalline interface was shallower than the tail of the
boron implant, some channeling occurred. This channeling tail exhibited an
enhanced diffusion during the single-step RIA which was reduced
significantly by the two-step anneal. When the amorphous layer was deeper
than the boron implant, the single-step and two-step anneals gave identical
results.
Impurity Diffusion During RTA
Authors: Fair R.B.
Published: March 2011

Enhanced dopant diffusion during RTA depends upon whether the following
physical phenomena occur individually or in combination: (1) amorphization
of the Si, (2) damage-induced dislocation formation, (3) damage annealing,
(4) self-interstitial trapping, (5) solubility enhancement. RTA of B in
crystalline or preamorphized Si presents significantly different
environments for enhanced diffusion. In preamorphized Si, enhanced B
diffusion is modeled as increased B solubility following SPE. In addition, a
different intrinsic diffusivity is observed which corresponds to B diffusion
in preamorphized Si. Anomalous diffusion of B and As from high dose implants
can be modeled with the same mechanism -- self-interstitial trapping
following SPE.
Solid-Phase Epitaxial Regrowth of Ion-Implanted Silicon on
Sapphire Using Rapid Thermal Annealing
Authors: Hodge A M , Cullis A G , Chew N G
Published: March 2011

Solid phase epitaxial regrowth of silicon on sapphire is used to improve the
quality of as-received silicon films prior to conventional device
processing. It has been shown that this is necessary, especially for layers
of 0.3μm and thinner, if the full potential of this particular silicon on
insulator technology is to be realised. Si+ ions are implanted at
an energy and dose such that all but the surface of the silicon film is
rendered amorphous. In this study, the layer is regrown using a rapid
thermal annealer operated in the multi-second regime. A second shallower
implant followed by rapid thermal annealing produces a further improvement.
Characterisation of the material has been principally by cross-sectional
transmission electron microscopy. The structures observed after different
implant and regrowth treatments are discussed.
Epitaxy and Defects in Laser-Irradiated, Single-Crystal
Bismuth
Authors: Helms Aubrey L. , Draper Clifton W. , Jacobson Dale C. , Poate John M. , Bernasek Steven L.
Published: March 2011

The (0001), (1010), and (2110) faces of Bi have been pulse laser melted at
0.5 J/cm2 with a Q-switched Ruby laser. Nomarski Interference
Contrast Microscopy, Channeling, and selective chemical etching have been
used to investigate the response to the laser irradiation. The response of
the material and the level of damage is shown to be strongly correlated to
the critical resolved shear stress characteristics in the particular
crystallographic direction studied.
Optical Furnace Annealing
Authors: Barrett Neil J. , Bartle D.C. , Todd A.G. , Grange J.D.
Published: March 2011

The rapid annealing of Be implanted GaAs has produced electrical activations
of 70% for doses of 5 × 1014 cm−2 and hole profiles
similar to the as implanted distribution. Si implanted GaAs has also been
investigated using doses of 1 and 2 × 1014 cm−2 with
sheet resistivities of 40 Ω/square after rapid thermal annealing. GaAs has
been annealed with W-Si on the surface for the application of self aligned
gate FET technology. Temperature cycles upto 850°C are required to activate
the implanted dopant. Such cycles do not cause inter diffusion between the
W-Si and GaAs or deterioration of the metallisation surface morphology.
Rapid Thermal Annealing of Tisi2 for
Interconnects
Authors: Rosser P.J. , Tomkins G.J.
Published: March 2011

A self-aligned polycide gate interconnect process has been developed at STL
in order to reduce the RC delays in existing and planned MOS circuits. This
process has been chosen due to its ease of implementation into an existing
process line. Incoherent lamp annealing is used to form the silicide after
the deposition of titanium over patterned polysilicon.

This paper will discuss the various materials and processes considered,
outlining the significant attributes of each. The factors which must be
controlled to achieve a practical process are discussed, together with the
degree of redistribution of dopants and the role of other impurities.
The Microstructure of Transiently Annealed Donor Implants in
GaAs
Authors: Shahid M.A. , Bensalem R. , Sealy B.J.
Published: March 2011

Undoped SI (100) GaAs has been implanted with selenium and tin ions at room
temperature at an ion energy of 300 keV and using ion dose in the range 1 ×
1014 to 1 × 1015 ions cm−2. Transient
annealing at 1000°C and above has been studied using electrical measurements
and transmission electron microscopy. The results show that tin implanted
samples have comparatively higher values of electrical activity and mobility
than those implanted with selenium ions. A difference in the microstructure
of these two implants was observed. Selenium implanted samples show
dislocation lines and loops possessing 1/2<110> Burgers vectors while
tin implanted GaAs contains dislocation loops of 1/2<110> and
1/3<111> types and also dislocation lines having 1/2<110>
Burgers vectors. Both types of defect in tin implanted samples are decorated
with precipitates.
Rapid Thermal Annealing of Si-Implanted GaAs for Power
FETs
Authors: Kanber H. , Cipolli R. J. , Whelan J. M.
Published: March 2011

Optimization and the advantages of rapid thermal annealing (RTA) for the
electrical activation of deep 300 keV Si+ implants into GaAs are
investigated and established for doses of 6 to 8×1012
cm−2. These implant conditions are appropriate for power FETs.
Results are compared with those based on conventional controlled atmosphere
capless furnace annealing (CAT).

The RTA yielded higher peak electron concentrations, high mobilities and
greater uniformities in the gateless FET saturation currents. The deep
implant results ontrast with those for shallower implants for low noise
FETs. These differences are explained using a well-known implant damage
model.
Ion-Induced Mixing in Ni-Sio2
Bilayers
Authors: Banwell T. C. , Nicolet M-A. , Grunthaner P. J. , Sands T.
Published: March 2011

We report on our studies of Ni transport induced by 300 keV Xe irradiation
of 25 nm Ni films evaporated on thermally grown SiO2 at Xe
fluences of 1013-1016 cm-2 and at
temperatures of 300-750 K during irradiation. Cross-sectional TEM, and
selective etching combined with 2 MeV He backscattering spectrometry and
ESCA were used to profile the Xe and Ni within the SiO2. At 300
K, backscattering shows cascade mixing dominates, although only ~ 1/35 that
predicted by cascade theory, with most of the Ni in the SiO2
contained in a resolution limited peak adjacent to the SiO2
interface. TEM shows that this Ni is contained in a 5 nm band, 5 nm below
the interface as Ni oxide clusters. Examination of the satellite structure
of the Ni 2p line by XPS also shows this band is predominantly
Ni2+. At 750 K, the near-surface peak vanishes and only recoil
implantation is evident. Ni0 is evident by XPS in samples irradiated at 300
K, though not at higher temperatures. We explain our results in terms of
phase separation during cooling of the collision cascade.
Pulsed Ion-Beam Induced Reactions of Ni And Co With Amorphous
and Single Crystal Silicon
Authors: Olowolafe J. O. , Fastow R.
Published: March 2011

Thin layers (~1,000 A ) of Ni and Co have been reacted with both (100) and
amorphous silicon (a-Si) using a pulsed ion beam. Samples were analyzed
using Rutherford backscattering, x-ray diffraction, and transmission
electron microscopy. Rutherford backscattering showed that the metal/a-Si
and metal/(100)-Si reaction rates were comparable. Both reactions began at
the composition of the lowest eutectic. For comparison. furnace annealing of
the same structures showed that the reaction rate of Ni with amorphous
silicon was greater than with (100) Si; Co reacted nearly identically with
both substrates. Diffraction data suggest that pulsed ion beam annealing
crystallizes the amorphous silicon before the metal/a-Si reaction
begins.
Solid-Liquid Interface Instability in the Energy-Beam
Recrystallization of Silicon on Insulator
Authors: Lee El-Hang
Published: March 2011

An attempt has been made to systematically sort out the characteristic modes
of morphological transition in the energy beam recrystallized thin film
silicon on insulating substrates, and to relate them to the mechanisms of
solid-liquid interface stability breakdown. Stable to unstable breakdown
modes include faceted, cellular, and dendritic configurations as well as
transient and composite configurations thereof. These primary modes of
breakdown then lead to the secondary modes of breakdown which constitute the
sub-boundary formation. The mechanics of the primary (interface) breakdown
and that of the secondary (sub-boundary) breakdown must be clearly
differentiated in understanding the breakdown process. Constitutional
supercooling and absolute supercooling models have been used to explain the
various interface instabilities.
Characterization, Control, and Reduction of Subboundaries in
Silicon on Insulators
Authors: Geis M. W. , Chen C. K. , Smith Henry I. , Mountain R. W. , Doherty C. L.
Published: March 2011

Subboundaries are the major crystalline defects in thin semiconductor films
produced by zone-melting recrystallization (ZMR). Using transmission
electron microscopy (TEM) and chemical etching we have analyzed the angular
discontinuity and defect structure of subboundaries in ZMR Si films.
Annealing in oxygen has resulted in the elimination of dislocation bands
from sizable regions of some films. Calculations suggest that cellular
growth due to constitutional supercooling may not occur in some Si ZMR.
Improved Crystal Perfection in Zone-Recrystallized Si Films on
Sio2
Authors: Pfeiffer Loren , West K. W. , Paine Scott , Joy D. C.
Published: March 2011

We review recent results of our Graphite Strip Heater Si-on-Insulator (SOI)
effort: (i) recrystallization of SOI films on 100 mm wafers, (ii) model of
subboundary pattern formation in SOI films, (iii) low defect density SOI
films by ultra slow scanning of the melt zone, (iv) low defect density SOI
films by patterned openings in the cap oxide overlayer.
Laser Recrystallization and 3D Integration
Authors: Colinge J.P.
Published: March 2011

There are various methods for producing device-worthy Silicon-on-Insulator
films, most, however, are unsuitable for fabrication of 3D integrated
structures. The laser recrystallization technique is currently the only one
which has produced single-crystal devices for 3D ICs. Improvements on this
technique have been such that defects such as grain boundaries can be
localized and even eliminated. High speed CMOS circuits with VLSI features
have been realized as well as new devices which take advantage of the 3D
arrangement of vertically integrated structures. Although 3D integration is
still in the early stages of development, it has already opened up new
perspectives for applications such as high speed circuits, dense memories,
and sensors.
Single Crystalline SOI Square Islands Fabricated by Laser
Recrystallization Using a Surrounding Antireflection Cap and Successive
Self-Aligned Isolation Utilizing the Same Cap
Authors: Mukai R. , Sasaki N. , Iwai T. , Kawamura S. , Nakano M.
Published: March 2011

A new laser recrystallizing technique has been developedfor high density
SOI-LSI's. This technique produces single crystalline silicon islands on an
amorphous insulating layerwithout seed. Square windows are opened at
arbitrary places in an antireflection cap over a polycrystalline film on an
amorphous insulatinq layer. Grain boundaries of the polycrystalline Si in
the window are removed completely at the subsequent laser-recrystallization
step. Single crystalline silicon islands are formed by self-aligned etching
of silicon film which was covered by the antireflection cap. This technique
is an effective method for fabricating high density SOI-LSI's, since the
singlecrystalline islands can be fabricated at arbitrarily selected places.
Yield of the grain-boundary-free islands was 95% the size of the island is
1O x 20μm, and the irradiation oyerlap of laser-beam traces is 70%.
Formation of Si-On-Insulator Structure Under Solid Phase
Growth
Authors: Miyao M. , Moniwa M. , Warabisako T. , Sunami H. , Tokuyama T.
Published: March 2011

Two possible solutions to the problem of nucleus growth encountered in
lateral solid-phase epitaxial growth over insulating films are discussed. A
stress field originating from the thermal expansion coefficient for Si and
SiO2 acts as the driving force behind preferential nucleation.
Utilization of underlying Si3N4 films successfully
eliminated nucleii growth at topographically irregular portions. In
addition, single crystallization of poly-Si nucleii was achieved on SOI
structures for the first time. Lateral growth speed (v [cm/s]) of 1.6 × 10
exp(−3.9/kT[eV]) was obtained during high-temperature annealing (≥1000 C
).
Solid Phase Processes for
Semiconductor-On-Insulator
Authors: Thompson C.V.
Published: March 2011

A wide variety of techniques for producing device-quality semiconductor
films on insulating substrates (SOI) are being studied. Processes which
provide low defect density films at low temperatures and which do not
require seeding from a single crystal substrate would offer the greatest
flexibility. While such processes do not currently exist, approaches based
on crystallization of amorphous silicon or grain growth in polycrystalline
silicon are being investigated. Development of either approach requires
careful control of film properties and improved understanding of the
fundamental materials processes involved. Theory and experiments on
surface-energy-driven secondary grain growth (SEDS6G) are briefly reviewed.
Controlled SEDS66 may provide a low temperature means of obtaining low
defect density films of a variety of materials on a common substrate.
Grain Growth Processes during Transient Annealing of
As-Implanted, Polycrystalline-Silicon Films
Authors: Krause S.J. , Wilson S.R. , Paulson W.M. , Gregory R.B.
Published: March 2011

Polycrystalline silicon films of 300 nm thickness were deposited on oxidized
wafer surfaces, implanted with As, and annealed on a Varian IA 200 rapid
thermal annealer. Transmission electron microscopy was used to study
through-thickness and cross sectional views of grain size and morphology of
as-deposited and of transient annealed films. A bimoda] distribution of
grain sizes was present in as-deposited polycrystalline silicon films. The
first population was due to columnar growth of some grains to a final
average diameter of 20 rm. The second population of small equiaxed grains of
5 nm average diameter were formed early in the deposition process. During
transient annealing grains in the first population grew rapidly up to 280-nm
equiaxed grains. After this the growth rate decreased due to the grain size
reaching the thickness of the film. Grains in the second population grew
rapidly up to a size of 150 nm, after which the growth rate was lowered due
to grains impinging upon one another. The grain growth processes for both
populations have been described with a modified model for interfacially
driven grain growth. This model accounts for diffusion and grain growth
which occur with rapidly rising and falling temperatures during short
annealing times characteristic of transient annealing processes.
Investigation of Point Defects in Si by Impurity Diffusion
Authors: Mizuo Shoichi , Higuchi Hisayuki
Published: March 2011

Our investigation of impurity diffusion in Si has clarified diffusion mechanisms and the point defect structure for the material. Thermal equilibrium between interstitials and vacancies in high temperature Si was clarified through observation of oxidation-retarded diffusion (ORD) of Sb in Si. Boron, Phosphorus, Aluminum and Galium were found to diffuse mainly due to an interstitialcy mechanism, while Sb did by a vacancy mechanism. Moreover, the atomic number in Si crystal compared to that at lattice sites was seen to play a dominant role in determining point defect concentration. Oxidation of Si and nitridation of SiO2on Si lead to an increase in the atomic number of Si crystals and cause an increase in interstitial concentration as well as a decrease in vacancy concentration. On the other hand, nitridation of Si leads to a decrease in atomic number and causes vacancy super-saturation as well as interstitial under-saturation.
Annealing and Diffusion of Boron in Self-Implanted Silicon by Furnace and Electron Beam Heating
Authors: Godfrey D. J. , McMahon R. A. , Hasko D. G. , Ahmed H. , Dowsett M. G.
Published: March 2011

The annealing and diffusion behaviour of ion implanted boron over a wide range of doses in as-received and pre-amorphised silicon (180 keV 5 × 1015 cm−2 silicon implants) has been studied using conventional furnace annealing and multiple scan electron beam heating in the rapid isothermal annealing mode. The layers obtained have been characterised using spreading resistance profiling (SRP), SIMS and TEM.

For furnace annealing the silicon implantation produces improved electrical activation for boron doses in excess of 1015 cm−2. SIMS and SRP data indicate that a higher level of peak activation has been achieved, whilst the overall amount of redistribution has been restricted. The reduction in diffusion achieved (∼0.2 μm) is greater than the maximum difference attributable to the effect of lower ion channelling for the silicon implanted samples. Cross-sectional TEM has been used to determine the resulting defect structure and provides insight into the details of the stable precipitated boron surface peak observed. A numerical diffusion model has been developed to allow interpretation of these experimental findings.

Similar samples have been annealed using multiple scan electron beam heating (peak temperatures up to 1100°C for times up to 300 s). For silicon implanted with boron alone, where cooling commenced once the peak temperature of 1100°C had been reached, diffusion was restricted to 0.05 μm while the sheet resistance (32 Ω/square) was reduced by ∼25% compared to furnace anneals at 950°C. Identical annealing of silicon implanted samples produced improved activation with a sheet resistance of 26 Ω/square. Results from SIMS, SRP and TEM analysis of these experiments are reported.
On the Interaction of Intrinsic and Extrinsic Gettering Schemes in Silicon
Authors: Yang K. H. , Tan T. Y.
Published: March 2011

We report some results of an experiment designed to study the interaction of extrinsic-gettering (EG) and intrinsic-gettering (IG) schemes. We found that mechanical abrasion introduces interstitial type dislocations into the wafer backside, and produces a concave wafer frontside. The EG dislocation network enhances SiO2 precipitation which is responsible for the IG activity. The enhancement is most significant near the wafer backside. The interaction arises most probably because the dislocation network serves as a very efficient source/sink for point defects.
Nucleation Time Effects on Intrinsic Gettering
Authors: Wongm C.-C. D. , Malwah M. L. , Pollock L.
Published: March 2011

In this study, nucleation time has been found to play an important role in the three-step (Hi-Lo-Hi) intrinsic gettering process. The longer the nucleation time, the higher the density of oxygen precipitates and oxidation induced stacking faults. The size of oxidation induced stacking faults, however, shrinks as the nucleation time increases. The reduction of junction leakage current indicates that gettering efficiency improves with increasing nucleation time. Oxidation induced stacking faults appear to be the dominant gettering sites.
Temperature Ramping for Nucleation of Oxygen Precipitates in Silicon
Authors: Pinizzotto R. F. , Schaake H. F. , Massey R. G. , Heidt D. W.
Published: March 2011

A new method for the nucleation of oxygen precipitates in Czochralski silicon is described. The temperature is ramped at approximately 100°C/hr from a very low value, near 400°C, to the highest temperature used for subsequent process steps. The technique generates a larger precipitate number density and a greater volume fraction of precipitated oxygen than standard isothermal nucleation anneals. The morphology of the precipitates changes from 0.lum sizéd (100) platelets to small particles unresovable by TEM. The new temperature ramping technique can reduce the time needed for precipitate nucleation by at least a factor of three. The details of oxygen precipitation can be totally controlled by adjusting the temperature ramp rate as a function of time.
Pressure Dependence of Arsenic Diffusivity in Silicon
Authors: Nygren Eric , Aziz Michael J. , Turnbull David , Hays James F. , Poate John M. , Jacobson Dale C. , Hull Robert
Published: March 2011

The diffusivity of implanted As in crystalline Si has been measured using Rutherford backscattering and channeling for specimens annealed at temperatures between 850 and 1000°C under pressures up to 30 kilobars. The diffusivity, at a given temperature, was found to increase with pressure with a maximum increase of a factor of ten. This diffusivity enhancement can be described by an average activation volume of -5.7±.8 cm3/mole. The activation enthalpy ranges from an ambient value of 4.5 eV to 3.6 eV at 30 kilobars
Epitaxial Silicon on Yttria-Stabilized Cubic Zirconia (YSZ) and Subsequent Oxidation of the Si/YSZ Interface
Authors: Mercandalli L. M. , Pribat D. , Dupuy M. , Arnodo C. , Rondi D. , Dieumegard D.
Published: March 2011

Astract

(100) single crystal silicon films have been deposited onto (100) oriented Yttria-Stabilized Zirconia (YSZ) substrates by pyrolysis of SiH4 at ∼ 980°C.

The as deposited epitaxial silicon films have been characterized by Reflexion High Energy Electron Diffraction and Transmission Electron Microscopy techniques.

The as deposited silicon films have also been oxidized by oxygen transport through the substrate, resulting in a Si(100)/ amorphous SiO2/YSZ(100) structure in which the most defective part of the epitaxial silicon deposit has been eliminated. The oxidized interfaces (with SiO2 thicknesses in the 2000 Å range) have then been characterized by Transmission Electron Microscopy in order to assess the improvement in crystalline quality. Electrical measurements have also been performed on MOS-Hall bar structures.
Strained-Layer Superlattices and Strain-Induced Light Holes
Authors: Osbourn G. C.
Published: March 2011

The capability of growing high quality strained-layer superlattices (SLS's) from lattice-mismatched semiconductors opens up new opportunities in both basic and applied material sciences. This flexibility in the choice of SLS layer materials allows the study of quantum well effects in a variety of new and interesting heterojunction systems. In addition, the large tetragonal distortions of the SLS layers allow these structures to exhibit unique features which are not found in bulk semiconductors. An exciting example is the possibility of tailoring certain SLS materials so that they exhibit small two dimensional hole effective masses and enhanced low field hole mobilities at low temperatures and low carrier concentrations. Band structure calculations indicate that the layer strains, the direct band gap magnitudes of the layers, the valence band offset, and the hole energies all can play a role in determing these small two dimensional hole effective mass values.
Luminescence Properties of InxGa1-xAs-GaAs Strained-Layer Superlattices
Authors: Anderson N. G. , Laidig W. D. , Lee G. , Lo Y. , Ozturk M.
Published: March 2011

The low-temperature (20K) photoluminescence of InxGa1-xAs and InxGal-xAs - GaAs strained-layer superlattices (SLS's) grown by molecular beam epitaxy (MBE) is investigated. Data are presented for thick (bulk) epitaxial layers grown directly on GaAs and for relatively-thin (˜600Å) InxGa1-xAs layers under biaxial compression. Data are also presented for two series of SLS's. In the two series of SLS's, the InxGa1-xAs layer thickness (Lz) is held constant while only the GaAs layer thickness (LB) is varied. The photoluminescence (PL) spectra of the crystals are useful in analyzing the effects of biaxial strain, carrier confinement, and barrier layer thicknesses in SLS's. Results are compared with calculations based upon a modified Kronig-Penney model which incorporates the appropriate deformation potentials for SLS analysis. This type of analysis, in agreement with experimental data, suggests that the electron-to-light-hole transition can be lower in energy than the electron-to-heavy-hole transition in SLS's, depending upon layer thickness and crystal composition.
Interfacial Structure and Stability in GexSi1−x/Si Strained Layers.
Authors: Hull R. , Bean J. C. , Gibson J. M. , Marcantonio K. J. , Fiory A. T. , Nakahara S.
Published: March 2011

High resolution electron microscopy is used to probe the atomic scale structure of interfaces and defects in the GexSi1−x/Si system. By careful quantification of lattice images, it is shown that molecular beam epitaxy may be used to grow GexSi1−x/Si (100) and (111) interfaces which are sharp on the scale of the unit cell and flat to within a few atomic planes when about 5000 Å2 of the interface are sampled. Interfacial quality is retained in single and multiple quantum well structures. Conditions for superlattice stability against misfit dislocations are discussed. It is shown that GexSi1−x/Si interfaces produced by molecular beam epitaxy at 550°C can exist in a metastable state which relaxes upon thermal annealing.
A Review of Recent Results on Single Crystal Metastable Semiconducfors: Crystal Growth, Phase Stability, and Physical Properties
Authors: Barnett S. A. , Kramer B. , Romano L. T. , Shah S. I. , Ray M. A. , Fang S. , Greene J. E.
Published: March 2011

Recent results on metastable semiconducting alloys, concerning in particular the growth of new Sn-based alloys (GaSb)1−x(Sn2)x and Gel−xSnx and the physical properties of (GaAs)1−x(Ge2)x and (GaSb)1−x(Ge2)x, are discussed. (GaSb)1−x(Sn2)x and Ge1−xSnx alloy films were grown with x-values as high as 0.20 and 0.15, respectively, well in excess of equilibrium Sn solid solubility limits (<1%) while epitaxial (GaAs)1−x(Ge2) and (GaSb)1−x(Ge2)x alloys were obtained on (100) GaAs at compositions ranging across the pseudobinary phase diagram. Low energy ion bombardment induced collisional mixing and preferential sputtering during film growth played a critical role in obtaining single phase alloys. An optimal ion energy, which depended on the ion flux and the alloy composition, was determined, allowing in most cases growth at temperatures T, sufficient for obtaining single crystal alloys on (100) GaAs and (100) Ge substrates. Decomposition of the Sn-based alloys occurred above a critical Ts- value via α-Sn-rich precipitates which were stable above the β-Sn melting point. X-ray diffraction, STEM, EXAFS, and Raman spectroscopy measurements, performed on single crystal (GaAs)1−x(Ge2)x and (GaSb)1−x(Ge2)x alloys, indicate that there is a transition in the long-range order from zincblende to diamond with increasing x while the short-range order remains perfect at all compositions, i.e. no V-V or III-Ill bonds are observed. These results are discussed in light of recent models which relate (GaAs)1−x(Ge2)x atomic structure to its band structure and optical properties.
An Evaluation of Implantation-Disordering of (Inga)As/Gaas Strained-Layer Superlattices
Authors: Myers D. R. , Barnes C. E. , Arnold G. W. , Dawson L. R. , Biefeld R. M. , Zipperian T. E. , Gourley P. L. , Fritz I. J.
Published: March 2011

We have examined the optical and transport properties of In.2Ga.8As/GaAs straled-kayer superlZotices (SLS's), which have been implanted either with 5 × 1015/cm2, 250keV Zn+ or with 5 × 1014/cm2, 70keV Be+ and annealed under an arsenic overpressure at 600 °C. For both cases, electrical activation in the implantation-doped regions equalled that of similar implants and anneals in bulk GaAs, even though the Be implant retained the SLS structure, while the Zn implant intermixed the SLS layers to produce an alloy semiconductor of the average SLS composition. Photoluminescence intensities in the annealed implanted regions were significantly reduced from that of virgin material, apparently due to residual implant damage. Diodes formed from both the Be- and the Zn-implanted SLS's produced electroluminescence intensity comparable to that of grown-junction SLS diodes in the same chemical system, despite the implantation processing and the potential for vertical lattice mismatch in the Zn-disordered SLS device. These results indicate that Zn-disordering can be as useful in strained-layer superlattices as in lattice-matched systems.
Schottky Barrier Heights at Singe Crystal Metal Semiconductor Interfaces
Authors: Tung R. T.
Published: March 2011

Electrical behavior at single crystal silicide-silicon interfaces was studied. Schottky barrier heights were determined for epitaxial NiSi2 and CoSi2 layers grown under ultrahigh vacuum conditions on (111), (100) and (110) surfaces of Si. A dependence of Schottky barrier heights on interface structure was observed. These results favor intrinsic mechanisms for Schottky barrier formation. The advantages of having homogeneous metal-semiconductor interfaces for the study of Schottky barrier mechanisms are pointed out. In particular, the present epitaxial silicide-silicon interfaces represent ideal candidates for detailed theoretical investigations based on experimentally obtained atomic structures.
Ion Channeling and Blocking Study of Ultra-Thin NiSi2 Films Grown on Atomically Clean Si(111) Surfaces
Authors: Van Loenen E. J. , Van Der Veen J. F.
Published: March 2011

Epitaxial NiSi2 films of less than 40 Å thickness have been grown on atomically clean Si(111) surfaces. Ion channeling and blocking have been used to determine the morphology and orientation of these films, as well as the strain resulting from the lattice mismatch with the Si substrate. The films are found to be continuous for Ni coverages above 5×1015 atoms/cm2. For all coverages the films are (111) oriented but rotated 180° around the surface normal with respect to the substrate. The NiSi2-Si(111) interface has been probed directly by the ion beam and is found to be well ordered and atomically abrupt.
Pinning Action of a Thin Ga Interfacial Layer in an Sb/Ga/GaAs Schottky Barrier Structure Grown by MBE
Authors: Zhang X.-J. , Cheng H. , Milnes A. G.
Published: March 2011

The pinning action on the barrier height of a Ga interfacial layer in an Sb/Ga/GaAs structure prepared by molecular beam epitaxy has been tracked as a function of Ga layer thicknesses for both n and p-GaAs (100). The barrier height ÆBn for n-type GaAs (ND=3×1015cm−3), determined by thermal activation measurements and capacitance measurements, changes from 0.8 to 1.0 eV as the Ga layer is increased from zero to three monolayers. The barrier height ÆBp for p-type GaAs decreases in a converse fashion so that the sum ÆBn + ÆBp is equal to the GaAs energy gap. Up to a Ga layer thickness of about one monolayer the barrier height changes are about linearly proportional to thickness.

The action seen is compatible with barrier height changes that are seen when Sb/GaAs junctions are prepared with the original surface alternatively As or Ga rich and subjected to thermal annealing at temperatures up to 250°C.
Atomic Structure of the Epitaxial Al/Si Interface
Authors: LeGoues F. K. , Krakow W. , Ho P. S.
Published: March 2011

Al was deposited on Si(l l l) and observed by cross-sectional electron microscopy, both in the annealed and as deposited states. It is shown that Al is strongly textured when deposited on Si(111), with Al(111)//Si(111) and AI<110>//Si<110> or AI(100)//Si(111) and AI//Si<110>. Annealed samples are completely epitaxial with A1(111)//Si(111) and A1<110>//Si<110>. Lattices imaging of the interfaces shows an amorphous layer (native Si oxide) between Al and Si, in the as-deposited case. The two lattices are in contact only at pinholes in the native oxide and fringes on both sides of the interface are seen to be continuous through the interface only at those points. Annealed samples do not show any amorphous or disordered layer at the interface: The two lattices are completely in contact, with lattice fringes extending from one side of the interface to the other. An atomic model of the annealed interface, based on energy considerations and consistent with TEM observations, is proposed.
Effects of Incommensuracy on the Structural and Electrical Properties in PbTe-Bi Superlattice Films
Authors: Shin Sung-Chul
Published: March 2011

We studied the structural and electrical transport properties of incommensurate PbTe-Bi superlattice films. The properties of those samples were noticeably different from those of commensurate samples. For the incommensurate samples, the satellite peaks, in the 9–29 x-ray scans along the [111] growth orientation, became broader and the ratio of satellite intensities to the Bragg intensity became smaller. The resistances of incommensurate samples were about three times larger than those of corresponding commensurate ones. These features are interpreted by an enhancement of the lateral nonuniformity of interfaces in incommensurate samples. The exponential dependence of the resistance on temperature in incommensurate samples was also in contrast to the logarithmic behavior observed in commensurate ones.
Observation of the CdTe-GaAs Interface by High Resolution Electron Microscopy
Authors: Otsuka N. , Kolodziejski L. A. , Gunshor R. L. , Datta S. , Bicknell R. N. , Schetzina J. F.
Published: March 2011

CdTe films have been grown on GaAs substrates with two types of interfaces - one with the epitaxial relation (111)CdTe║ (100)GaAs and the other with (100)CdTe║ (100)GaAs,. High resolution electron microscope observation of the two types of interfaces was carried out in order to determine the role of the substrate surface microstructure in determining the epitaxy. The interface of the former type shows a direct contact between the CdTe and GaAs crystals, while the interface of the latter type has a very thin oxide layer (∼10 Å in thickness) between the two crystals. These observations suggest that details of the substrate preheating cycle prior to film growth is the principle factor in determining which epitaxial relation occurs in this system. The relation between interfacial structures and the origin of the two epitaxial relations is discussed.