bluuebunny/crossref_metadata_2025 huggingface dataset:
The Characterization of Silicon Damaged by Low Energy Argon Ion Etching
Authors: Seager C. H. , Panitz J. K. G. , Pettit R. G. , Brice D. K.
Published: March 2011

We have used a variety of characterization techniques including electron spin resonance (ESR), photothermal deflection spectroscopy (PDS), ellipsometry, and I–V and C-V analysis to study silicon samples damaged by 500–1500 eV Ar ions from a Kaufman ion source. In agreement with our ballistic penetration calculations, PDS and ellipsometry data show that the majority of the lattice damage lies within 40Å of the surface. The ellipsometry results are well modelled as a thin, damage-induced layer of a- Si with a high (4.63) refractive index, while the PDS measurements show an Urbach-like subgap adsorptance tail. In addition to Schottky barrier height alterations produced by Ar bombardment, we also observe marked changes in electrically active dopant densities in boron doped silicon samples. C-V analyses show that these changes extend quite far (1–2 μm) into the sample and are readily removed by a mild (150°C) thermal anneal. Hydrogen, injected from surface adsorbed H2O or hydrocarbons, appears to be the source of these effects. We will also discuss our upper limit estimate of 1013 “dangling bond” spins/cm2 for our damaged samples in light of prior ESR observations on similarly treated surfaces.
The Role of F Atoms in the Reactive Sputter Etching of Silicon Dioxide: Langmuir Probe and Optical Actinometry Measurements
Authors: Steinbrüchel C H. , Curtis B. J.
Published: March 2011

Reactive sputter etching of SiO2 in a low-pressure CF4 -O2 plasma has been investigated using a Langmuir probe to determine ion fluxes to the substrate and optical actinometry to monitor the concentration of F atoms, [F]. Etch yields Y, i.e. the number of substrate atoms removed per impinging ion, are obtained vs O2 composition and vs pressure. At constant pressure Y decreases slightly, but [F] increases considerably, with increasing O2 content. On the other hand, at constant O2 composition both Y and [F] increase strongly with increasing pressure. These results suggest that at low [F], relative to the ion flux to the substrate, the dominant etch mechanism is direct reactive ion etching, with the ions themselves as the main reactants, whereas at high [F] the overall etching is ion-enhanced, with F atoms as the main neutral reactants.
Surface Characteristics of Monocrystalline ß-SiC dry etched in fluorinated gases
Authors: Palmour John W. , Davis R. F. , Astell-Burt P. , Blackborow P.
Published: March 2011

Monocrystalline ß-SiC (100) thin films were dry etched in CF4 and NF3 by reactive ion etching (RIE) and in SF6 by plasma etching. The etched surfaces were characterized by Auger Electron Spectroscopy (AES) and Scanning Electron Microscopy (SEM). The use of a stainless steel or an anodized Al cathode during RIE created a roughened SiC surface, which was contaminated with Fe or Al2 O3respectively. The roughness was caused by a micromasking effect produced by the deposition of these contaminants. By contrast, a carbon cathode yielded a very smooth and a much cleaner etched surface. Plasma etching of SiC in SF6 resulted in a very rough surface, but the AES spectra indicated almost no contamination and very little native oxide or fluorine. The optimal condition for etching SiC was determined to be RIE in NF 3 on a C cathode.
A Silicon Field Emitter Array Planar Vacuum FET Fabricated with Microfabrication Techniques
Authors: Gray Henry F. , Campisi G. J.
Published: March 2011

In this paper we will discuss a new type of field effect transistor, a vacuum FET, where the usual channel material is the vacuum rather than a semiconductor. This new device is based on Field Emitter Arrays (FEA) which are inherently submicron structures. That is, the field emitters themselves must have dimensions less that 0.1 micrometers in order to generate the high electrostatic fields necessary for electron tunneling, and the control gate (or extraction electrode) must be very close to the field emitter tip in order to generate these high fields with reasonable voltages. Consequently, this new “FET” is the first of a new class of vaccum electronic switching devices based on microfabrication techniques, and susceptible to circuit integration.
Gettering Processes for Sub-Micron VLSI
Authors: Andrews John
Published: March 2011

Gettering by the dislocation network caused by P-diffusion into the back surface of Si wafers at 950° C for 1 hr. is often used for VLSI. However, transistors with sub-micron gates are jeopardized at 950°C because of possible source-drain punch through by lateral P-diffusion. The temperature dependence of gettering by P-diffusion has been investigated at 950, 900, and 850°C. Gettering by P-diffusion was found to be marginal at 900°C and totally ineffective at 850°C.

Recently published data on the solubility and diffusivity of interstitial oxygen in Czochralski-grown Si has been used to develop a simple out-diffusion model for denuded zone formation during thermal oxidation. Comparison with experimental observations on samples with high interstitial SiO2 concentration [Oi]0, exposed to dry oxidation at 1100° C for various times up to 8 hrs. and followed by 24 hr. anneals in N2 at 700°C and 1050°C, reveal that SiO2 precipitation occurs when the supersaturation ratio exceeds 4.7. The model implies an optimum denuding temperature near 100° C for a dry oxidation time of 4 hrs. The bulk defect density was also observed to decrease more than a factor of 5 as the denuding time was increased from 0 to 8 hrs.

Intrinsic gettering by SiO2 precipitates in Czochralski-grown silicon has been evaluated over a wide range of initial interstitial oxygen concentrations 15 < [Oi]0 < 22 ppma with and without a HI-LO-HI pre-process annealing cycle. Among samples of approximately 100 p-n junctions per wafer, reductions of 1–3 orders of magnitude in reverse leakage at 5 volts were achieved in the worst 10% of 500 μm square devices on wafers that were exposed to the HI-LO-HI heat treatment. Intrinsic gettering is most effective when [Oi]0 22 ppma, but leakage reduction among the worst diodes is achieved at the expense of a 2 or 3-fold increase in median leakage.
Inside Submicron MOSFETS
Authors: Skocpol W. J.
Published: March 2011

Nanofabrication techniques allow us to carve out narrow (40 nm) conducting channels and multiple voltage probes inside a submicron portion of a “conventional” silicon MOSFET. The repeated capture and emission of single electrons at a particular interface trap can be observed, because this changes the number of scatterers, producing sudden switching of the conductance. The dependence of capture and emission rates on lattice temperature, electron temperature, and gate voltage are consistent with a simple “configuration coordinate” model of the coupling between the trapped electron and the surrounding lattice. At low temperatures, the electrons being scattered diffuse considerable distances Lϕ before losing quantum phase information. When measured at scale Lϕ, random quantum interference causes a typical (rms) conductance change of e2/h = (25.8 kΩ)−1 (“universal conductance fluctuations”). From this, the resistance fluctions at longer and shorter voltage probe spacings can be predicted. Each scatterer substantially affects the quantum interference throughout a region of size Lϕ.
Electron Bean Induced Defects in Silicon/Indium Oxide Heterojunctions and Interfacial Reactions During Annealing
Authors: Kar S. , Pandey A. , Dwivedi R. K.
Published: March 2011

Si/In203 diodes have been prepared by e-beam evaporation of In203 tablets. Annealing of these devices was carried out in N2 and H2 /N2 mixture at 1 atm. in the temperature range of 400–800°C. Experimental data indicated a large increase in the Schottky barrier height and growth of interfacial oxide during annealing. The interface state density was reduced by a factor of 2, but the results indicated the increase in the barrier height to be mainly due to reduction of positive fixed charge density.
A Soluble Polydiacetylene, P4BCMU, As a Negative Electron Beam Resist
Authors: Marrian C. R. K. , Colton R. J. , Snow A. , Taylor C. J.
Published: March 2011

The polydiacetylene with urethane substituents, P4BCMU, has been investigated under e-beam irradiation. A thin, ∼ (100nm), coating can be applied to a silicon wafer by spin coating from a solution in chloroform. E-beam exposure of around 20μC/cm2 renders the polymer insoluble and resistant to a CF4 /O2 plasma etch and a RIE with freon 112. Features down to .2μm have been drawn and etched in this way. X-ray Photoelectron Spectroscopy indicates only a slight change in stoichiometry and suggests the irradiated polymer has tertiary amide characteristics. Fourier Transform Infra Red and Raman spectroscopies indicate that the unsaturated carbon bonds in the backbone of the polymer are not destroyed by e-beam irradiation. Rather the main changes occur in the N-H and the C=O (carbonyl) bonds of the urethane group.
Thermal and Mechanical Properties of Cyclized Polybutadiene Dielectrics
Authors: Wilkins C. W. , Bair H. E. , Chan M. G. , Hutton R. S.
Published: March 2011

We have studied some of the physical and mechanical properties of cyclized polybutadiene (CBR) dielectrics by dynamic mechanical analysis, thermal mechanical analysis, thermogravimetry, infrared analysis, and differential scanning calorimetry. Of interest is the difference in properties between thin (<30 μm) films which have been cured under vacuum and those which have been cured in air. Our results indicate that curing under vacuum prevents oxidation and reduces crosslinking. Vacuum cured films have 20% smaller moduli and 200 lower glass transition temperature than do films produced in air.
Microfabrication Technologies for Advanced VLSI Devices
Authors: Horiike Y. , Yoshikawa R. , Okano H. , Nakase M. , Komano H. , Takigawa T.
Published: March 2011

Recent progress in microfabrication technologies for advanced VLSI devices, such as 16M and 64MDRAM, is presented. First, an EB delineator with a vector-scanned VSB on a moving stage has been developed for printing 0.25 μm patterns employing PMMA, high dose exposure, and 50 KeV EB. Optical lithography also has been extended toward lower submicron geometry. A Krf excimer laser reduction projection system, using a quartz/CaF2 lens, resolves successfully 0.35 μm patterns. Ga field ion beam technology has been developed with new applications in fuse-cutting of redundancy and in optimizing sense amplifier by cutting transistor gates in the SRAM device. For fine line etching technology, collimated reactive ions produced by 10−3 Torr magnetron discharge achieves deep Si trench etching and tapered Al etching by using a polymer deposition process in addition to the original thin sidewall film. Finally, a damage-free excimer laser etching process has been developed which can etch n+ poly-Si with resist mask and with pattern transfer using an optics down to 0.5 μm and 0.9 μm resolutions respectively.
Silicon as a Mechanical Material
Authors: Petersen Kurt
Published: March 2011

Now that single crystal silicon has established itself as the preeminent electronic material, increasing applications are being implemented in which silicon's MECHANICAL properties are more important. This paper reviews some of the history behind this trend, explains how and why silicon can be an economical and effective mechanical material, and describes several of the devices which have been demonstrated in this technology.
Imaging of III-V Compound Superlattices by Hrem and Rem
Authors: De Cooman B. C. , Conner J. R. , Summerfelt S. R. , McKernan S. , Carter C. B. , Shealy J. R.
Published: March 2011

Two techniques for the analysis of III-V compound superlattices are examined. It has been proposed that high-resolution TEM of [100]-oriented thin foils would give an improvement in layer contrast compared with [110]-oriented thin foils; it is shown here that the contrast of [100]-oriented superlattices is not necessarily better. Moreover, both high resolution and conventional dark-field imaging may be subject to significant diffraction contrast effects resulting from the bending of the reflecting planes near the surface of the sample. Reflection electron microscopy (REM) of cross-sectional (110) cleavage planes can also yield dark-field superlattice images and selected area RHEED patterns can in principle be used to determine reliably the superlattice strain as surface effects are minimized.
Effects of Self-Ion Bombardment on Al/Si(n) Schottky Barrier Formation
Authors: Wong J. , Mei S.-N. , Lu T.-M.
Published: March 2011

We have employed a nozzle jet expansion technique to deposit Al thin film on chemically cleaned Si(n) surface. Pure Al is evaporated in a graphite crucible at a temperature of 15 50°C and is then ejected through a small nozzle into a vacuum region of 10-6 Torr. The Schottky barrier height of the as-deposited films is measured (using the J-V technique) to be 0.77eV, which is substantially higher than that obtained by conventional evaporation-deposition techniques(≤0.68eV). Our result suggests that an intimate Al/Si(n) contact has been formed during the jet expansion deposition of Al films.

During the deposition, the Al jet beam can be partially ionized by electron bombardment. It is shown that the Schottky barrier height remain unchanged if a bias potential of V s0.5KeV is applied to the substrate during deposition. For Va >0.5 KeV, the diode became leaky and the barrier height was reduced. The energetic of the jet beam, with and without post ionization and acceleration, is discussed with respect to thin film and interface formation.
The Structure of Al/GaAs Interfaces
Authors: Liliental-Weber Zuzanna , Nelson C. , Gronsky R. , Washburn J. , Ludeke R.
Published: March 2011

The structure of Al/GaAs interfaces was investigated by high resolution electron microscopy. The Al layers Were deposited in a molecular beam epitaxy chamber with a vacuum base pressure of <1×10∼8 Pa. The GaAs substrate temperature varied during Al deposition from -30°C to 400°C. Deposition of Al on cold substrates £25°C resulted in epitaxial growth of (001) Al on (001) GaAs. Droplets of Ga were observed in samples with the substrate temperature at -30°C (1×2) and 0°C (c(2×8)). Postannealing of the last sample caused formation of the AlGaAs phase. Deposition of Al on hot substrates (150°C and 400°C) resulted in the formation of the AlGaAs phase, which separated (110) oriented Al from (001)GaAs.
High-Resolution Core Level Studies of Interdiffusion and Reaction at Metal-Semiconductor Interfaces
Authors: Del Giudice M. , Joyce J. J. , Boscherini F. , Capasso C. , Weaver J. H.
Published: March 2011

We present a detailed microscopic investigation of interactions and reactions occurring at refractory-metal silicon interfaces at room temperature. High resolution core level photoemission results for Ti coverages in the range 0.2–16 monolayers on cleaved Si(111)2×1 show that three new distinct Si environments are created by semiconductor surface disruption. In agreement with heats of formation or electronegativity differences, all the chemical shifts are at lower binding energy. Each of them represents a different metal-Si coordination or configuration. Analogous results for Sc overlayers indicate that at least two reacted species are present. For both Ti and Sc, the reaction is started at submonolayer coverages. Analysis of the Si 2p intensity attenuation curves shows an evolution characterized by the sequential growth of the different species. Indeed, each species grows, reaches saturation, and is then attenuated. This is associated with the competition between diffusion and reaction at the interface.
Atomic Registry at the Pt-Si Interface Studied by Transmission Channeling RBS
Authors: Abelson John R. , Sigmon Thomas W.
Published: March 2011

Transmission channeling Rutherford scattering of MeV ions is one of the only techniques which can probe the atomic registry at a “buried” internal interface between a thin film and single-crystal substrate. Interfacial intermixing, dislocations, and reconstruction can be observed at concentrations above ∼ 3×1015 atoms/cm. The physical basis for this measurement is the “flux-peaking” effect, which is well known in conventional ion channeling as a method to determine the lattice location of dilute impurities. Transmission channeling is conceptually similar, but the scattering arises from the interface at the exit side of a thin single crystal sample rather than from a volume effect.

In this work, we apply transmission channeling to measure the low temperature intermixing between Pt and Si. In a previous study, we suggested that a disordered interface forms prior to crystalline suicide formation. The present results are a quantitative measurement of the area density of Si which intermixes with Pt at 150°C. Experiments are performed using 80A Pt layers e-béam deposited onto 1–2μm thick single crystals of Si(100) and (111) following various interfacial cleaning procedures. We find that >1×1016 Si atoms/cm2 are displaced from their lattice sites after Pt deposition, increasing to ∼2×1016/cm2 upon annealing to 150°C. The room temperature intermixing of >6 monolayers of Si is large, but not inconsistent with existing studies of the Pt - Si reaction. The transmission channeling measurement includes any Si segregated at grain boundaries or the free surface as well as the interface. No systematic differences are observed as a function of substrate orientation or cleaning procedure.
Studies of MZS and MZOS Structures with Zinc Oxide Deposited by Conventional Rf Diode and Magnetron Sputtering Techniques
Authors: Venkatesh S. N. , Ramakrishnan E. S. , Jungling K. C. , Krupanidhi S. B.
Published: March 2011

Highly crystalline and c-axis oriented zinc oxide thin films were sputter deposited from a ceramic target using rf diode and magnetron sputtering techniques. A comparative evaluation of structure and electrical characteristics of ZnO films in the MZS and MZOS configurations is presented and the results are discussed. The physical and electrical properties were significantly influenced by highly energetic particles originating from the presence of oxygen neutrals in the plasma during the growth process and the behavior differed between the diode and magnetron sputtering processes.
Metallurgical Reactions in Au/Ge/Au Contact to Gallium Arsenide
Authors: Kim Taeil , Chung DDL , Mahajan S
Published: March 2011

Transmission electron microscopy (TEM), was used to study the interfacial structure resulting from the alloying reaction of a Au/Ge/Au film on (100) GaAs. The metallurgical reaction at 400°C results in the previously unknown hexagonal Au3Ga phase. The crystal structure of the AuoGa phase is proposed based on the observed diffraction patterns and the lattice image The well-known fcchcp coherent jnterface is observed between Au and Au3Ga such that (111)Au // (0001)Au3Ga and [110]. // [1120]Au2Ga. In addition to Au3Ga, other Au-Ga compounds (Au7Ga2, Au2Ge), a Au-Ge metastabil phase, and a Au-Ge-As ternary phase were observed after annealing. After annealing above 400°C, epitaxially regrown GaAs crystallites on the underlying GaAs substrate were revealed by cross-section TEM. The current flows through these Ge-doped regrown GaAs regions and the contact becomes ohmic The size and density of the regrown GaAs crystallite increase with increasing annealing temperature between 400 and 500°C; this explains the decreasing tendency of contact resistance with increasing annealing temperature.
Silicon Membrane Studies of Point Defect Transport Kinetics During Thermal Oxidation
Authors: Ahn S. T. , Shott J. D. , Tiller W. A.
Published: March 2011

Self-interstitial transport kinetics in float-zone and Czochralski silicon was studied during thermal oxidation of silicon membranes. Bulk recombination of interstitials is higher in the CZ than in the FZ silicon. The low apparent interstitial diffusivity obtained in this study is explained by a bulk effect.
Growth and Characterization of Chemically Vapor Deposited Beta-Sic Epilayers on 6H Alpha-Sic Substrates
Authors: Kong H. S. , Glass J. T. , Davis R. F. , Nutt S. R.
Published: March 2011

High quality, β-SiC (111) monocrystalline films have been epitaxially grown via chemical vapor deposition at 1683K on hexagonal 6H αc-SiC (0001) using a (SiH4 + C2H4)/(H2) gas flow rate ratio of 1:3000. Cross-sectional transmission electron microscopy showed almost no line or planar defects at the film/substrate interface and a low density within the bulk of the film. Furthermore, high resolution transmission electron microscopy revealed a coherent β-SiC/α-SiC interface. Secondary ion mass spectrometry indicated that the diffusion of the Al in the substrate into the as-grown film was negligible. Unintentionally doped films are n-type with the carrier concentrations virtually always in the range of 1016-1017cm3, as determined by capacitance-voltage measurements. A gold-β-SiC Schottky diode having an ideality constant of approximately 1.6 was fabricated on the β-SiC epilayer.
Doping Effects in GaAs/AlGaAs Superlattices
Authors: Chambers Frank A. , Vojak Bruce A.
Published: March 2011

We present the results of a study we have done to explore the effects of high levels of Be dopant, >1×1019 /cm3, in GaAs/AlGaAs superlattice structures. The materials were grown using Molecular Beam Epitaxy (MBE) at 680 C using standard growth conditions. The samples were studied using a variety of structural, optical and electrical probes. Structural data obtained from Auger and SIMS profiling is presented as well as optical data from photoluminescence and Raman scattering. We also present the results of electrochemical profiling of the samples. The results of these studies provide evidence of intermixing of the superlattice during growth with sufficiently high Be levels. We have found evidence for a concentration threshold in the diffusivity of Be in these structures. We also find that the dominant mechanism for Be redistribution in these samples appears to be diffusive in nature rather than due to surface riding.
Stress Release in Ion Implanted Lattice Mismatched Semiconductor Heterostructures
Authors: Arnold G. W. , Picraux S. T. , Myers D. R. , Doyle B. L. , Peercy P. S. , Biefeld R. M. , Dawson L. R.
Published: March 2011

Cantilever-beam measurements of ion-implantation induced stress in (InGa)As/GaAs, Ga(AsP)/GaP, and Ga(AsP)/GaAs strained layer superlattices (SLSs), grown either by molecular-beam epitaxy (MBE) or metalorganic chemical vapor deposition (MOCVD), have shown that a mechanism for precipitous stress-relief can be operative, f or room-temperature damage -energy deposition values above - 2 × 10 keV/cm. This phenomenon is correlated with the initial residual compressive stress on the composite structure and is determined by the differences in lattice parameter between the substrate and the buffer alloy-layer.
Effects of Implant Temperature on Disordering of AlAs-GaAs Superlattices
Authors: Dobisz E. A. , Tell B. , Craighead H. G. , Schwarz S. A. , Tamargo M. C. , Harbison J. P.
Published: March 2011

The effect of implant temperature, superlattice period, and directional diffusion has been studied for silicon impurity-enhanced compositional disordering of GaAs-AlAs superlattices (SL) of 9 ran and 16 nm period. The SL were implanted with Si at temperatures of 483 K, 293 K, and 77 K, with an energy of 100 keV and dose of 2.5 × 1014 cm-2. These were examined by cross-sectional transmission electron microscopy and secondary ion mass spectro-scopy for structural and compositional information. The damage due to implantation prior to annealing is strikingly less for superlattices than for bulk GaAs. All annealed samples exhibited disordering, with the 9 nm period SL exhibiting a deeper disordered region than the 16 nm SL. The greatest enhancement was found in the 9 nm period SL implanted at 77 K, in which the disordering extended from a depth of 25 nm to =300 nm. The mixing was found to be anisotropie, with the SL mixing propagating greater in depth than in the lateral directions. The result has important implications for high resolution patterning possibilities with this method.
Photoemission Study of the Physical Nature of the InP Near-Surface Defect States
Authors: Chin K. K. , Cao R. , Kendelewicz T. , Miyano K. , Yeh J. J. , Doniach S. , Lindau I. , Spicer W. E.
Published: March 2011

The physical nature of the InP near-surface defect acceptor and donor states are studied by using photoemission spectroscopy. It is found that the In/n-InP(110) interface band bending does not start until the In coverage reaches about 0.3 monolayer (ML), while the In/p-InP(110) band bending is almost saturated at 0.3 ML. The annealing effect on the band bending of clean cleaved n-and p-type InP(llO) surfaces is also studied. It is found that annealing of the clean surface creates an irreversible band bending effect on the p-InP(110), but the n-InP(110) almost does not show any band bending after low temperature annealing. Based on these two striking differences in the band bending behavior of n- and p-type InP, it is proposed that the physical nature of InP near-surface defect acceptor and donor levels may be different and that phosphorus vacancies are the cause of p-InP surface Fermi level pinning.
Atomistic Calculation of Stability and Metastability of Coherently Strained Silicon-Like Structures
Authors: Dodson Brian W. , Taylor Paul A.
Published: March 2011

Monte Carlo based microscopic techniques were used to study the stability and metastability of thin coherently strained layers of mismatched siliconlike semiconductor material grown on the (111) silicon surface. The structural energy was calculated using three-body empirical potentials. For layers greater than about 20 Å thickness, the critical layer thickness associated with thermodynamic stability agrees quantitatively with continuum theory. For thinner layers, however, considerable variations from the continuum theory are found. For a strained layer six monolayers thick, the test system is found to be metastable against the nucleation of misfit dislocations to a lattice mismatch of about 11%, compared to the 4% equilibrium stability limit.
Theoretical and Experimental Description of Interface Structure
Authors: Hull R. , Carey K. W. , Reid G. A.
Published: March 2011

We define the Interface between two dissimilar materials by two functions, g(z) and f(x,y), representing the diffuseness along the interface normal and the distribution of interface non-planarities respectively. We show how these functions may be measured for the case of epitaxial interfaces between dissimilar crystals by quantitative analysis of lattice structure images obtained by high resolution transmission electron microscopy. Experimental examples are drawn from the GeSi/Si, InGaAs/InAlAs and InGaAs/InP systems. Correlations between interface structure and optical and electronic properties of these systems are discussed.
Compositional Studies of Semiconductor Alloys by Bright Field Electron Microscope Imaging of Wedged Crystals
Authors: Eaglesham D. J. , Hetherington C. J. D. , Humphreys C. J.
Published: March 2011

The use of a cleaved 90 degree wedge as a cross section sample for transmission electron microscopy allows the composition of III/V semiconductor alloys to be measured by studying the thickness fringes of the on-axis [010] bright field image. The effect is explained in terms of the incident electron Bloch states and is illustrated by reference to GaAs/AlGaAs. The technique has an accuracy of about 5% and a spatial resolution of a few Å. The range of materials that can be analysed in this way is discussed.
Grain Growth in Vapor Deposited Aluminium Alloys
Authors: Köster Uwe , Ho Paul S.
Published: March 2011

In a number of vapor deposited aluminium alloys grain growth has been investigated systematically by means of quantitative electron microscopy and found to proceed not by grain boundary migration, but by grain coalescence. Parameters influencing the observed mode of grain growth will be discussed with respect to the formation of microstructures with optimal resistance to electromigration, i.e. microstructures with large grain size, high homogeneity in the grain size distribution as well as a strong texture.

Analyses of grain size distribution after annealing indicate a strong retardation in grain growth by the solute in all aluminium alloys except Al(Cu). Relative large grain sizes and very small lognormal standard deviations have been observed in Al-l%Cu as well as ternary Al(Cu,Hf) thin films.
Nanocontact Measurements in Superlattices
Authors: Baumann T. , Pethica J. B. , Grimsditch M. , Schuller Ivan K.
Published: March 2011

Many metallic superlattices are known to exhibit dramatic anomalous elastic properties as a function of modulation wavelength. All measurements to date measure either a shear modulus or a longitudinal modulus in the superlattice plane. Here we present a method which also probes longitudinal elastic behavior perpendicular to the layers using a nano-hardness tester. In this method, a diamond tip is indented into the material and both the indentation depth and applied force are constantly monitored during loading and unloading. The elastic properties are extracted from the unloading part of the force versus displacement curve. Contrary to the anomaly found in a shear modulus, no anomaly in Young's modulus was found in the present study on Mo/Ni superlattices.
Intrinsic Stress and Structure in Mixed Composition thin films
Authors: Sankur Haluk , Denatale J. , Gunning W. J.
Published: March 2011

Intrinsic stress and microstructure of mixed composition films were investigated for several material systems useful in the IR wavelength range. Stress in coevaporated mixed films (analog) deviated from a linear dependence on composition, while in discrete alternating films (digital) it varied linearly with composition. For MgF2-Ge and CeF3-Ge, analog film stress was small and compressive over a large range of intermediate compositions despite the fact that the constituent materials had high tensile stress. The stress behavior correlated with changes in the microstructure. Low stress compositions were observed to correspond to enhanced grain size in the mixed film. These results have significant implications for the design of gradient-index thin-film structures.
Correlations and Ordering in (GaSb)1−xGe2x Alloys
Authors: Newman Kathie E. , Gu Bing-Lin , Fedders P. A.
Published: March 2011

The semiconducting alloy (GaSb)1−x Ge2x is an example of a mixed crystalline alloy that undergoes a phase transition between its constituent crystal types. The order-disorder transition modifies both the long-range and short-range order in the alloy as a function of composition x. By using the Kikuchi approximation, the bond probabilities are calculated and then compared with EXAFS data. These calculations show that the EXAFS data are consistent with the existence in (GaSb)1−x Ge2x of “wrong” bonds of Ga-Ga and Sb-Sb. The theory also predicts a violation of Vegard's Law for the behavior of the mean bond length as a function of composition x.
The Structure of a-Si:H,F/a-Si,Ge:H,F Interfaces
Authors: Conde J. P. , Shen D.-S. , Campbell I. H. , Fauchet P. M. , Wagner S.
Published: March 2011

We study the interface between un-alloyed a-Si:H,F and an a-Si0.4,Ge0.6:H,F alloy using superlattice structures. From infrared spectroscopy we estimate a width of 8 A for the excess hydrogen layer, and X-ray diffraction data give us a width of 2Å contributing to the width of the diffraction peak. Vibrational Raman scattering data show that the ratios of the number of Si-Si, Ge-Ge and Si-Ge bonds is not altered by changing the number of interfaces. This fact allows us to establish an upper limit for the interface width of 3 atomic layers, i.e. one layer in each partner plus an intermediate layer.
Optical Modulation Spectroscopy of a-Si:H Based Multilayer Structures
Authors: Zhou T. X. , Stoddart H. , Vardeny Z. , Tauc J. , Abeles B.
Published: March 2011

Steady state optical modulation spectrum of a-Si:H/a-SiNx:H multilayer structure, its temperature dependence and time decay have been studied. For multilayers with very thin sublayers the onset of the spectrum is more gradual and occurs at higher energy than the spectrum for unlayered a-Si:H, indicating a broadening of the band tail. For larger layer thicknesses the optical modulation spectrum is compared to that for P-doped a-Si:H and interpreted as due to charged dangling bonds at the interfaces.
Exafs Studies of Grain Boundary Diffusion and Segregation
Authors: Heald S. M. , Chen H. , Tranquada J. M.
Published: March 2011

The dominant pathway for thin film interdiffusion and interface reactions is often via grain boundaries. We have made EXAFS measurements of grain boundary constituents for two systems: interdiffusion in Ag-Au bilay-ers and solid state reaction of Nb with a copper-tin bronze to form Nb3Sn. The Ag-Au results indicate that Au in saturated Ag grain boundaries has an environment similar to a dilute Au in Ag solution with reduced coordination. For the Nb-bronze reaction, the results for the Cu environment indicate distinct changes in the grain boundary environment when small amounts of Ti, Hf, Zr, and Ta are added to the starting Nb. Both results demonstrate the ability of EXAFS to probe grain boundary environments, and to provide important structural information in understanding solid state diffusion and interdiffusion in thin film systems.
Properties of Metal Fluoride Films Deposited by Laser and E-Beam Evaporation
Authors: Sankur Haluk , Woodberry F. , Hall R. , Gunning W. J.
Published: March 2011

The properties of metal fluoride films (MgF2 CeF3, LaF3 CaF2 and SrF2) deposited using cw laser and electron-beam evaporation were compared. The differences in film properties were subtle, but important. Films obtained by laser evaporation have lower losses in the UV (185–250 nm) and slightly better crystallinity than the films deposited by e-beam evaporation. Other optical and mechanical properties were independent of preparation method. Differences in the film properties were tentatively attributed to the higher proportion of dissociated species in the évaporant plume of the laser-evaporated materials.
Thin Metal Film Adhesion Studies on GaAs
Authors: Bardin T. T. , Pronko J. G. , Kinell D. K.
Published: March 2011

Comparative thin film adhesion studies were performed on GaAs substrates using Au or Au-Ni-Ge, metallization materials. The influence of parameters such as crystal orientation, substrate surface preparation, deposition vacuum conditions, thickness and composition of films, and post-evaporative treatment such as ion-beam mixing and thermal annealing, on film adhesion was considered. The quality of the adhesion bond was measured using Scotch tape tests and a Sebastian adhesion tester. Film interfaces were characterized using AES, XPS, and RBS techniques. The results indicate that the most important factors dominating the quality of adhesion were surface preparation and the deposition vacuum conditions. Films deposited under optimum conditions were found to adhere so well that the GaAs crystal would fracture before the film would pull free of the substrate. The influence of ion beam mixing on the quality of adhesion was tested and only in the cases of depositions under the less optimum conditions, where the adhesion was poor, could an improvement be made in the adhesive properties.
The Diffusion of Phosphorus and Indium into Gallium Arsenide from Polycrystalline-Silicon
Authors: Kavanagh K. L. , Magee C. W. , Mayer J. W.
Published: March 2011

Arsenic or phosphorus doped polycrystalline-Si (poly-Si) acts as a diffusion source when deposited on GaAs. Non-Fickian Si diffusion into GaAs has been observed following heat treatments above 700°C. In this paper, the diffusion of In and P from poly-Si at temperatures between 800 and 1020°C is presented. These impurities, introduced into the poly-Si by in-situ plasma deposition, implantation or vapor annealing, diffuse rapidly into the GaAs. Results from particle induced x-ray analysis, transmission electron microscopy, Rutherford backseat tering and secondary ion mass spectroscopy indicate 80% substitutional In and P at interface concentrations of approximately 10 and 25 at%, respectively.
Superconducting Mbtallic Supkrlattices
Authors: Falco Charles M. , Vaglio Ruggero , Cucolo Annamaria
Published: March 2011

Since the coherence length is of order 50 Å to 1 μm, it is possible to alternately layer thin films of a superconductor with another material to affect the physical properties of the resulting superlattice. A brief description of our sputtering technique used to prepare superlat t ices consisting of Nb/Cu and Ta/Mo is given. Optical interferometry, x-ray diffraction and ion beam analysis techniques independently confirm that control of ±0.3% is achieved over the amount of material deposited in each layer. Results of a study of Josephson tunneling to Nb/Cu metallic super lattices are reviewed. These measurements enable a determination of the London penetration depth to be made as a function of superlattice layer thickness.
Exafs Studies of Semiconductors
Authors: Bunker Bruce A.
Published: March 2011

Recent results from EXAFS spectroscopy are discussed, including (i) the determination of the site and local bond lengths of Fe impurities implanted into Si, (ii) the determination of the ferroelectric phase transition in Pb1−x Gex Te as order-disorder rather than displacive, and (iii) the nondestructive measurement of Aℓ diffusion into GaAs at an Aℓ/GaAs Interface.
Strength and Interfacial Properties of Ceramic Composites
Authors: Narshall D. B.
Published: March 2011

Results of recent micromechanics analyses of the reinforcing influence of frictionally bonded fibers in ceramic composites are summnarized. Direct measurements of the fiber/matrix interface properties are also discussed.
Constitutive Laws for Ceramics Exhibiting Stress-Induced Martensitic Transformation
Authors: Lambropoulos John C.
Published: March 2011

The theory of internal variables is used in order to develop multiaxial constitutive laws for ceramics undergoing martensitic stress-assisted transformation, such as partially stabilized zirconia or A12O3-ZrO2. The internal variable is identified with the volume concentration of transformed particles, and we assume that transformation occurs so that the change in potential energy due to the transformation is maximized. When the rate of transformation depends on the applied stresses only through the corresponding change in potential energy, it is shown that the inelastic strain rates are along the normal of a stress function in stress space. The constitutive law depends on all three stress invariants. We further discuss specific stress environments such as crack tip fields, the special case of homogeneous transforming particle distribution, and conditions under which normality is not obeyed.
Excinier Laser Radiation Induced Rapid-Solidification of Alunjinumi and Aluminumi Alloys
Authors: Antony G. , Strutt P. R.
Published: March 2011

A study of the effects of high intensity excimer laser radiation (249nm.) of aluminum and an Al-Si alloy reveals a variety of intriguing surface topographical features. Important parameters determining these include the energy-density and the number of short-duration (≈22ns.) pulses. Specific attention has been devoted to determining the condition for the onset of surface melting, and the physical effects of further increasing the energy density. A study of the frozen-in surface wave structure has been used to determine the approximate solidification time and the solidification-front velocity. As well as overall surface melting, an interesting phenomenon is the localized melting occurring at precipitates which preferentially absorb the incident radiation. This phenomenon has been studied in an Al-Si alloy subjected to single and multiple pulses; the effect of the latter has been found to have a striking effect.
Unusual Rapidity of Electron Beam Transient Tempering
Authors: Tauqir Anjum , Strutt Peter R.
Published: March 2011

Electron beam rapid solidification of molybdenum-base high speed steels results in quenched-in metastable phases containing a high concentration of alloying elements. Thermal reprocessing of such material by momentary interaction with the electron beam results in decomposition of martensite at a rate ≈ 100 times faster than that occurring during conventional thermal treatment. It is postulated that this arises from a high concentration of 'defect cluster nucleation sites' during the rapid up-quenching. The product of short thermal treatment is a dispersion of 2–5 nm very fine precipitates identified using transmission electron microscopy as MC type carbides.
Preparation and Gas Addition of Soft Magnetic Pure Iron Thin Film by Dual Ion Beam Sputtering
Authors: Nagakubo M. , Kawano A. , Naoe M.
Published: March 2011

Pure iron thin films with soft magnetic properties and good chemical stabilities have been prepared by Dual Ion Beam Sputtering (DIBS). Four kinds of gas, that is, hydrogen, helium, nitrogen and argon were introduced respectively to the auxiliary ion source as the additional element in the film and also for the purpose of bombardment during deposition. The dependence of crystal structure and magnetic properties of the films on the preparation condition, especially, on the effect of various gases added in the films by ion bombardment onto the depositing film surface, has been investigated.

Saturation magnetization 4πMs of iron film including gas atoms is usually smaller than that of bulk iron which has 4πMs of 21.5kG. For example, 4πMs of the film prepared by conventional planer magnetron sputtering remains about 15kG. Such a remarkable difference in 4πMs may be primarily attributed to the considerable amount of argon atoms included in the film due to argon pressure as high as 10mTorr. It may be also caused by high energy particles bombarding onto the iron film surface during deposition. On the other hand, pure iron thin films prepared by Dual Ion Beam Sputtering can have 47Ms as high as 21.5kG, and coercive force Hc as low as about 4 Oe by controlling the ratio of sputtering iron atoms to argon gas atoms, impinging onto the substrate, and the arrival energies both of them. Magnetic properties and crystal structures of the iron thin films depend significantly on the kind of added gas. In this study, it has been found that bombardment and addition of adequate gas atoms with proper energy results in an improvement of atomic ordering and microscopic uniformity in the films.
Magnetic Properties of Composite Amorphous Powder Cores
Authors: Chang Hong-Yow , Yao Pei-Chih , Huang Der-Ray , Hsu Shu-En
Published: March 2011

Composite amorphous powder core made by field-annealing with new insulations could improve the high frequency AC magnetic and mechanical properties. All of the amorphous ribbons with composition Fe78B16Si5C and Fe40Ni38Mo4B17Si were annealed at temperature higher than their embrittlement temperature but lower than the crystallization temperature. After the ribbons become brittle, they were mechanically crushed and milled to produce powders with size about 50 ∼ 250μm. To make a core, the amorphous powders combined with insulation binder were put into an evacuted toroidal followed by hot mechanical compaction. The weight percentages of binder were about 3 wt%, 5 wt% and 10 wt%. Field-annealings were carried out for different conditions in an Ar (or N2) atmosphere chamber at elevated temperature with applied field about 10 Oe. The initial magnetization curve and saturation magnetization were measured by vibrating sample magnetometer (O≤H≤10 KOe). DC and AC magnetic properties such as permeability, coercive force, core loss, etc. were tested by B-H loop tracer. It shows the AC properties can be improved by increasing the particle size of the amorphous powder and by increasing the interparticle contacts at high frequency.
Magnetization Reversal in Amorphous TbFe Films
Authors: Calkins J. , Mansuripur M. , Ruane M.
Published: March 2011

Observations under polarized light of magnetization reversal in thin amorphous films of TbFe alloys indicate that the reversal process is initiated at inherent nucleation sites where reverse-magnetized domains appear at fields below coercivity. The nuclei then grow in time until they cover the entire sample. The process of nucleation and growth seems to be dominated by the microstructure, since samples with identical bulk magnetic characteristics (such as composition, hysteresis loop and coercivity) exhibit quite different reversal behavior. This process is also dependent upon the history of magnetization of the sample.
Formation and Consolidation of Mechanically Alloyed Amorphous Powders
Authors: Dolgin B. P.
Published: March 2011

Mechanical alloying (MA) of iron, cobalt, and nickel with titanium and also with samarium produces a continuous growth of an amorphous phase. X-ray diffraction analyses show that the growth of the phase is described by a square root of time law. Differential scanning calorimetry data also confirm that mechanically alloyed powders are amorphous. Dry MA and MA in the presence of toluene are compared. The rate of alloying is much higher in the presence of toluene. Amorphous powders re-alloyed with the fast diffuser are consolidated by means of extrusion.
Bulk Amorphous Metals From Metallic Composites by Solid State Reaction
Authors: Schultz Ludwig
Published: March 2011

The amorphization reaction in mechanically prepared metallic Ni-Zr composites has been investigated by X-ray diffraction, electrical conductivity and magnetization measurements during isothermal annealing. The formation kinetics of the amorphous phase are determined by the diffusion of the Ni atoms across the amorphous NiZr layer. The diffusivity of Ni atoms in the initially formed amorphous Ni58.5 Zr41.5 is measured in the temperature range from 225°C (Dni= 5.3×10−17 cm2/sec) to 325°C (Dni= 1×10−14 cm2/sec). The data fit an Arrhenius plot with an activation energy of 1.4 eV. Magnetic coercivity measurements indicate that neither recovery nor recrystallization occurs in the Ni layers during the reaction. The Kirkendall effect caused by the anomalous fast diffusion of Ni is directly monitored by dilatometric measurements. Microhardness results are also presented. The role of a diffusion-related growth selection favoring the amorphous phase is critically assessed with respect to the glass formation.
An Atom Probe Study of Boron Segregation to Line and Planar Defects in Ni3Ai
Authors: Horton J. A. , Miller M. K.
Published: March 2011

Atom probe analyses of rapidly solidified, boron-doped Ni-24 at. % Al subjected to various heat treatments have shown boron segregation to a wide range of linear and planar defects. These include dislocations, superlattice intrinsic stacking faults, antiphase boundaries, twin boundaries, low-angle boundaries (dislocation cell walls), and high-angle grain boundaries. Boron coverage of these features was found to vary along a particular linear or planar defect and from boundary to boundary.
Site Occupation Determinations in Ni3Ai by Atom Probe
Authors: Miller M.K. , Horton J.A.
Published: March 2011

The site occupation of three substitutional elements, hafnium, iron and cobalt, in substoichiometric Ni3Al was determined from atom probe field-ion microscopy. The hafnium was found to have a strong preference for the aluminum sites, the cobalt had a strong preference for the nickel sites, and the iron had a weak preference for the aluminum sites. The atom probe results were in agreement with zone axis electron channeling microanalysis of the same alloys and predictions from the position of the solubility lobes in the ternary phase diagrams.
Lattice Occupation Determination of Hafnium in Ni3Al by Pac
Authors: Bohn H.G. , Schumacher R. , Vianden R.J.
Published: March 2011

Using the perturbed angular correlations technique we have investigated the intermetallic alloy Ni76Al24Hf1 in order to determine the lattice location of the Hf in the ordered Ni3Al structure. From the fact that the Hf atoms sense an electric field gradient it is concluded that most of the Hf resides on Ni-sublattice sites.