bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Role of Adsorption and Vapor Pressure in Focused Ion Beam Induced Deposition of Carbon Films
Authors: Kirch S.J. , Seeger D.E. 
Published: March 2011

ABSTRACTFocused ion beam induced deposition of carbon from various organic molecules was studiedfor a range of temperatures and pressures. To study the effects of vapor pressure, deposition from styrene was compared to deposition from 2-chloro and 2-bromo styrene. To study the effects of the double bond on the vinyl substituent, deposition from ethyl benzeneand 2-bromo ethyl benzene was compared to deposition from the 2-X-styrene materials. Foreach material, deposition yield is found to scale with vapor pressure as a function of temperature over the range studied (0 - 25 C). This behavior shows that physical adsorption plays the key role in determining deposition properties. The importance of the doublebond observed in previous work is simply a manifestation of enhanced physical adsorptiondue to the presence of this double bond.
Mechanism of Chromium Deposition from Cr(CO)6 by Uv Laser Light
Authors: Nowak R. , Hess P. 
Published: March 2011

ABSTRACTThe mechanism of metal film deposition from carbonyls as precursors is discussed in detail. It is shown that different species produced by UV laser irradiation in the gas phase contribute to film growth. Highly reactive species such as metal atoms may be important during the nucleation phase, whereas more stable carbonyls are responsible for the main growth process. This indicates that the main decarbonylation effect occurs at the surface. The higher level of impurity incorporation in chromium films in comparison with nickel films is explained by the relative position of the Fermi level in the d-band of Ni and Cr with respect to the 2π* level of CO, which favors CO bond dissociation in the case of chromium.
Selective Epitaxy of AlxGa1−x as and AlxGal−x as Based Structures
Authors: Goorsky M.S. , Kuech T.F. , Potemski R. 
Published: March 2011

ABSTRACTSelective epitaxy of AlxGa1−x As by MOVPE was accomplished using diethyl gallium chloride and diethyl aluminum chloride as the metalorganic precursors. Selective epitaxy was achieved for Al containing compounds under certain growth conditions, but AlAs growth was not selective. Quantum wells were selectively grown on masked substrates and unpatterned GaAs wafers; QW luminescence was observed from all samples. Additionally, near gap luminescence was observed from AlxGa1−x, As heterostructures over the entire 550 °C - 850 °C growth temperature range. The ternary alloy composition was found to be a strong function of the gas phase composition and growth temperature. A simple thermodynamic model explained the dependence of growth rate and composition on these parameters.
Optimized Molecular Beam Epitaxy Structures for GaAs on Silicon Photodetectors
Authors: Christou A. , Papanicolaou N.A. , Anderson G.W. 
Published: March 2011

ABSTRACTTwo dimensional growth of GaAs on silicon has been achieved by modulation molecular beam epitaxy (where the arsenic beam is pulsed) with laser assistance at 308 nm (LAMBE). Photoconductive, low doping concentration layers were utilized for metal-semiconductormetal photodetectors which were evaluated at 840 nm.
Atomic Structure of Dislocations and Interfaces in Semiconductor Heterostructures
Authors: Nandedkar A. S. , Sharan S. , Narayan J. 
Published: March 2011

ABSTRACTWe have studied and analyzed critical thickness required for the formation of misfit dislocations in semiconductor heterostructures. The present analysis has been carried out assuming that the nucleation of a misfit dislocation is controlled by the activation energy. The energy of the cohernt interface and the misfit dislocation configuration has been evaluated using a discrete dislocation analysis. Further, atomic structures of coherent and semicoherent interfaces containing misfit dislocations of the type a/2<110={111} ↑ <110= (600 dislocation), a/2<110={001} ↑ <110= (90° dislocation) and a/6<112={111} ↑ <110= (90° partial dislocation) in Ge/Si system were simulated. The total energy, consisting of both core and elastic energy components, was calculated using Stillinger-Weber interatomic potentials. The results show that the energy is a strong function of the nature of dislocations. A 60° dislocation is found to exist in undissociated form in shuffle configuration, but the core contains a dangling bond at the interface. The core of a 90° dislocation reconstructs at the Ge/Si interface with no dangling bonds. The calculated atomic configurations of dislocations and interfaces are found to be in good agreement with high resolution transmission electron microscopy observations.
Atomic Scale Study of Cosi/Si (111) and CoSi2/Si (111) Interfaces
Authors: Catana A. , Heintze M. , Schmid P.E. , Stadelmann P. 
Published: March 2011

ABSTRACTHigh Resolution Electron Microscopy (HREM) was used to study microstructural changes related to the CoSi/Si-CoSi/CoSi2/Si-CoSi2/Si transformations. CoSi is found to grow epitaxially on Si with [111]Si // [111]CoSi and < 110 >Si // < 112 >CoSi. Two CoSi non-equivalent orientations (rotated by 180° around the substrate normal) can occur in this plane. They can be clearly distinguished by HRTEM on cross-sections ( electron beam along [110]Si). At about 500°C CoSi transforms to CoSi2. Experimental results show that the type B orientation relationship satisfying [110]Si // [112]CoSi is preserved after the initial stage of CoSi2 formation. At this stage an epitaxial CoSi/CoSi2/Si(111) system is obtained. The atomic scale investigation of the CoSi2/Si interface shows that a 7-fold coordination of the cobalt atoms is observed in both type A and type B epitaxies.
Microstructural Aspects of Nickel Silicide Formation in Evaporated Nickel-Silicon Multilayer Thin Films
Authors: Holloway Karen , Clevenger Larry 
Published: March 2011

ABSTRACTThe early stages of the nucleation and growth of nickel silicides in Ni-Si multilayers evaporated onto oxide-stripped <100> Si substrates and annealed at 150 °C have been studied by cross-section transmission electron microscopy (TEM). Observed differences in the interaction of evaporated Ni with amorphous silicon and single crystal <100> Si have been explained by thermodynamic modeling of the Ni-Si system. The as-deposited films show a 3 nm amorphous Ni-Si intermixed layer at all Ni-Si interfaces, including that with the single-crystal Si substrate. Crystalline Ni2Si formed in all annealed films, consuming the elemental Ni layers. The amorphous alloy layer grows concurrently with Ni2Si during the reaction with a-Si; however, there is no amorphous phase present at the Ni2Si - <100> Si interface. Thermodynamic calculations show that at 150 °C metastable equilibrium might be expected between a-Si, the amorphous phase, and Ni2Si; but not between Ni2Si, the amorphous phase, and crystalline Si. The composition of the amorphous phase is very close to a-Ni50Si50. After a 6 hour anneal at 150 °C, crystalline NiSi forms between the a-Si and the Ni2Si layers by crystallization of the amorphous phase. Further annealing is necessary to form NiSi at the <100> Si - Ni2Si interfaces.
Stranski-Krastanov Growth of Ni on Si(111) at Room Temperature
Authors: Butler J. R. , Bennett P. A. 
Published: March 2011

ABSTRACTWe introduce quantitative Auger lineshape analysis methods to study the room temperature reaction of nickel on Si(111). We show that coexisting phases may be separated by numerically fitting the composite lineshapes using a linear combination of single phase “fingerprint” spectra, obtained by scraping bulk compounds in situ. The reaction proceeds in three stages. For nickel coverage below 1 Å, the growth is layerwise, forming NiSi2. For nickel coverage from 3 to 12 Å, islands of Ni2Si are formed. For nickel coverage above 12 Å, islands of pure nickel are formed. The overlayer reactions appear to be a kinetically limited form of Stranski-Krastanov growth, with multiple compound formation.
X-Ray Absorption Studies of Titanium Silicide Formation at the Interface of Ti Deposited on Si
Authors: Aldrich D.B. , Fiordalice R.W. , Jeon H. , Islam Q. , Nemanich R.J. , Sayers D.E. 
Published: March 2011

ABSTRACTNear edge X-ray absorption spectra (XANES) have been obtained from the Ti K-edge for several series of titanium silicide samples produced by different techniques. Samples were fabricated by depositing Ti on silicon wafers and subsequently annealing them up to temperatures from 100°C to 900°C in UHV, vacuum furnace, or in a Rapid Thermal Annealing system. Measurements were done in the fluorescence and total electron yield modes. The XANES measurements were correlated with Raman scattering measurements. The XANES data of several reference compounds were obtained, and the data showed a high sensitivity to changes in the film structure. Ti metallic bonding and Ti-Si bonds can be distinguished and their evolution as a function of annealing is related to previous results. For the samples with increased impurities, Ti regions were stable at higher temperatures. The XANES spectra of samples annealed under N2 indicate the formation of a surface nitride.
An NMR Study of Hydrogen in Si02 Films on Silicon
Authors: Levy David H. , Gleason K. K. 
Published: March 2011

ABSTRACTWe have used solid state nuclear magnetic resonance (NMR) spectroscopy to study both “wet” and “dry” thermally grown films of SiO2 on silicon substrates. For the 5000 § wet film, grown at 1050 °C we observed a single Lorentzian line of 6 kHz HWHM (half width at half maximum). For the 500 § dry film, we observed a convolution of two lines: a) a Lorentzian of 4 kHz HWHM and b) a Gaussian of 20 kHz HWHM. The hydrogen distributions in both oxides are interpreted as a function of these lines.
Onset of GaAs Homoepitaxy and Heteroepitaxy
Authors: Biegelsen D K. , Bringans R. D. , Northrup J. E. , Swartz L.-E. 
Published: March 2011

ABSTRACTWe present scanning tunneling microscopy images and atomic models for a variety of GaAs(100) reconstructed surfaces. For homoepitaxial material we show the sequence of phases from c(4×4) through c(8×2) as the As surface concentration is reduced. For the heteroepitaxial GaAs/Si(100) growth we show the first two stages of film development, namely, Si(100):As-(1×2) monolayer coverage followed by adsorption of a submonolayer of Ga dimers. The next stages of film development are discussed.
Low Energy Electron Microscopy of Surface Processes on Clean Si(111) and Si (100)
Authors: Bauer E. , Mundschau M. , Swiech W. , Telieps W. 
Published: March 2011

ABSTRACTLow energy electron microscopy (LEEM) is briefly introduced and its application to the study of surface defects, surface phase transitions on Si(111), crystal growth and sublimation on Si(100) is illustrated.
The Atomic Geometry of the Reconstructed (001) Surface of the Rutile Phase of SnO2
Authors: Duke Charles B. , Thompson Michael R. 
Published: March 2011

AbstractThe tight-binding total energy formalism developed for tetrahedrally coordinated compound semiconductors has been extended to rutile-structure oxides and applied to calculate the surface atomic geometry and electronic structure of SnO2 (001). Two stable structures, separated by an energy barrier, are found. The first consists of slightly relaxed surface geometry with the top layer oxygen atoms relaxed outward by approximately 0.12A, and cations inward by 0.25A. The second geometry is a more massively reconstructed surface in which the four-coordinate surface Sn atoms attain highly distorted tetrahedral coordination.
Interfacial Superstructures Studied by Grazing Incidence X-Ray Diffraction
Authors: Akimoto Koichi , Mizuki Jun'Ichiro , Hirosawa Ichiro , Matsui Junji 
Published: March 2011

ABSTRACTSurface superstructures (reconstructed structures) have been observed by many authors. However, it is not easy to confirm that a superstructure does exist at an interface between two solid layers. The present paper reports a direct observation, by a grazing incidence x-ray diffraction technique with use of synchrotron radiation, of superstructures at the interface. Firstly, the boron-induced R30° reconstruction at the Si interface has been investigated. At the a Si/Si(111) interface, boron atoms at 1/3 ML are substituted for silicon atoms, thus forming a R30° lattice. Even at the interface between a solid phase epitaxial Si(111) layer and a Si(111) substrate, the boron-induced R30° reconstruction has been also observed. Secondly, SiO2/Si(100)-2×l interfacial superstructures have been investigated. Interfacial superstructures have been only observed in the samples of which SiO2 layers have been deposited with a molecular beam deposition method. Finally, the interfaces of MOCVD-grown AIN/GaAs(100) have been shown to have 1×4 and 1×6 superstructures.
Bismuth Overlayer Formation on GaAs(110)
Authors: Chang S.-L. , Guo T. , Ford W.K. , Bowler A. , Hood E.S. 
Published: March 2011

ABSTRACTThe temperature and coverage dependent ordering of bismuth overlayers on GaAs(110) is examined using low energy electron diffraction (LEED). Sixth order electron diffraction profiles associated with overlayer ordering are observed at coverages of 0.7, 1.0, and 1.5 monolayers (ML) and for temperatures ranging from -110 C to 200 C. The full-width at half-maxima (FWHM) of the sixth-order spots are examined. Profile analysis reveals narrowing widths with increasing annealing temperature, indicating an improvement of the long-range ordering of the overlayers. Differences in inter- and intrachain ordering are observed, analyzed, and discussed.
Nanolayer Reactions in Aluminum-Metal Interfaces
Authors: Barrera E. V. , Ruckman M. W. , Heald S. M. 
Published: March 2011

ABSTRACTSurface extended x-ray absorption fine structure (SEXAFS) measurements on the nanometer level were made for AI/M interfaces where M was Cu or Ni. The samples were studied immediately after deposition and after heat treatments. Significant differences in interface reactions were observed depending on deposition direction (Cu on Al or Al on Cu) and the amount of mixing was also related to whether M was Cu or Ni. The SEXAFS measurements revealed that there were no detectable amounts of C or O present. One percent Zn was observed to be in the Al layers. The results obtained from the as-deposited interfaces correlate well with data obtained from buried interfaces of like element combinations.
Measurement of the Relative Position of Adjacent Crystals and the Modelling of Interfacial Structure
Authors: El-Eraki M.H.I. , Kiely C.J. , Pond R.C. 
Published: March 2011

ABSTRACTVarious techniques using transmission electron microscopy for determining the relative position of two crystals separated by an interface are reviewed briefly. Measurements obtained by these means can be used to identify unrelaxed interfacial configurations. The modelling of relaxed configurations based on these unrelaxed candidate structures requires additional information from experimental techniques such as electron diffraction and high resolution microscopy, or theoretical investigation by computer simulation. This procedure is illustrated for a selection of grain and interphase boundaries. {211} grain boundaries between twin related crystals of Al and Ge, and interfaces in NiSi2:Si, CoSi2:Si and AI:GaAs epitaxial systems, are discussed.
A Preliminary Observation on AgGaSe2 as a Nuclear Radiation Detector
Authors: Sakai Eiji , Horinaka Hiromichi , Sonomura Hajimu , Miyauchi Takeshi 
Published: March 2011

ABSTRACTAn about 108 ohm-cm AgGaSe2 crystal of 0.5 mm × 4 mm × 4 mm was polished and contacts were made by evaporating 130 μg/cm2 gold of 3 mm diameter on the two faces of the crystal. The detector was tested using 5.5 MeV alpha-particles at room temperature. Noise increased above an applied bias voltage of 80 V. For + 50 V applied on the electrode opposite to the particle incident electrode, i.e., for electron traversal mode, the preamplifier output pulses showed a risetime of 20 μs and an amplitude of about one-tenth of that obtained from a silicon surface-barrier detector whereas the silicon detector showed a risetime of 0.07 μs. For - 50 V applied on the same electrode, i.e., for hole traversal mode, no pulses were observed.
Fabrication of Ultra High Purity Silicon Single Crystals
Authors: Itoh D. , Kawamoto S. , Miki S. , Namba I. , Yatsurugi Y. 
Published: March 2011

ABSTRACTHigh resistivity silicon single crystals for radiation detectors were grown by the floating-zone (FZ) method with and without one-pass zone refining of ultra pure starting material obtained by the decomposition of monosilane gas. In this method, boron is removed from monosilane during gas generation. The main residual impurity is phosphorus from phosphine which is removed with zeolite A after distillation of monosilane. Photoluminescence analysis and an improved 4-point probe resistivity measuring method were used to evaluate the material.
The Relaxation of InxGa1-xAs/GaAs Strained Multilayers
Authors: Paine David C. , Howard David J. , Luo Dawei , Sacks Robert N. , Eschrich Timothy C. 
Published: March 2011

AbstractIn this paper we report on the kinetics of strain relaxation in GaAs/InxGa1-xAs/GaAs/AlAs (0.05<x<0.22) layers grown by MBE on GaAs at 520°C. We have characterized the density of dislocations present due to strain relaxation during both film growth and processing by using a large area thinning technique which enables the observation of approximately 2 mm2 areas by plan-view TEM. The thickness of the InxGa1-xAs layers studied was 36.4 nm and four compositions were chosen so that the critical thickness predicted by strain energy considerations was exceeded. Due, however, to sluggish dislocation nucleation and glide kinetics at the deposition temperature, the as-grown misfit dislocation densities were well below the predicted level for fully relaxed films. We have studied the rate at which these metastable strained films relax as a function of post-growth annealing time and temperature.
Surface Cross-Hatched Morphology on Strained III-V Semiconductor Heterostructures
Authors: Chang Kevin H. , Gibala Ronald , Srolovitz David J. , Bhattacharya Pallab K. , Mansfield John F. 
Published: March 2011

AbstractThe correlation between surface cross-hatched morphology and interfacial misfit dislocations in strained III-V semiconductor heteroepitaxy has been studied. The surface pattern is clearly seen on samples grown at high temperature (520°C) and with lattice mismatch f < 2%. A poorly defined cross-hatched morphology is found on layers grown at low temperature (400°C). For f > 2%, a rough textured surface morphology is observed in place of cross hatching. Few threading dislocations are observed in the strained layer when cross hatch develops. Cross hatch occurs after most interfacial misfit dislocations are generated. The results suggest that surface cross hatch is directly related to the generation and glide of interfacial misfit dislocations.
Thermal Stability of Strained InGaAs/GaAs Single Quantum Wells
Authors: Elman B. , Koteles Emil S. , Melman P. , Armiento C.A. , Jagannath C. 
Published: March 2011

AbstractWe present a study of the structural stability of InGaAs/GaAs strained single quantum wells (SQW) grown with a variety of indium compositions and with well widths close to critical thickness values. The samples were grown by molecular beam epitaxy and were subjected to furnace annealing as well as ion implantation followed by rapid thermal annealing. Changes in low temperature photoluminescence linewidths were used to evaluate the stability of strained SQWs. We observed both strain relief, in wide SQWs and strain recovery, in higher indium composition narrow quantum wells which were partially relaxed (low dislocation density) as-grown.
Thermal Disordering of Modulation Doped AlAs/GaAs Superlattice
Authors: Hara Kunihiko , Ito Hiroshi , Ohmi Shinya , Suzuki Takamasa 
Published: March 2011

AbstractInterdif fusion of Al and Ga in a Si modulation doped AlAs/GaAs superlattice was studied by photoluminescence technique. The diffusion coefficient of Al and Ga in the modulation doped superlattice is 1/3 to 1/2 of that of uniformly doped superlattice with the same average Si concentration. The dependence of the diffusion coefficient on the average Si concentration is similar to that of uniform doping.
Analysis of Strain Relaxation in Au/Ni Multilayers by X-Ray Diffraction
Authors: Chaudhuri J. , Gondhalekar V. , Shah S. , Jankowski A.F. 
Published: March 2011

AbstractThe strain distribution within individual layers in Au/Ni multilayer systems was obtained by an iterative fitting of the experimental x-ray diffraction pattern with a kinematic model. The depth profile of strain in the modulation direction was obtained for these metallic multilayers with repeat periodicities ranging from 1.19 nm to 4.26 nm. It was found that the role of interfacial coherency and strengthening is of great importance in understanding the origin of the supermodulus effect in metallic multilayers.
Epitaxial growth of Cr [001] on LiF [001]
Authors: Mattson J. , Brodsky M. B. , Ketterson J. , You H. 
Published: March 2011

AbstractWe report X-ray diffraction and in-situ RHEED( Reflection High Energy Electron Diffraction) measurements on Cr thin films deposited on LiF[001] single crystal substrates for thicknesses up to 300 nm and for substrate temperatures from 30 to 450°C. From these measurements we determine the range of deposition conditions necessary for epitaxial growth and the stress in these films as a function of film thickness.
Evolution of Stress During Heteroepitaxial Growth of NiSi2 on (001) and (111) Silicon Substrates
Authors: Ho H. L. , Bauer C. L. , Mahajan S. 
Published: March 2011

AbstractThin film stresses accompanying the nucleation and growth of NiSi2, resulting from the interaction of polycrystalline nickel films with (001) and (111) silicon substrates, have been measured at an annealing temperature of 825° C. Results Indicate a significantly larger stress reduction during the formation of NiSi2 on (111) silicon ( ~ 200 MPa) whereas the stress reduction is comparatively small (50–100 MPa) for the formation of NiSi2 on (001) silicon. TEM studies reveal that for NiSi2 on (111) silicon, two sets of dislocations in edge or mixed orientation are initially produced - one set consisting of Shockleys spaced 25Onm and a second set consisting of 5Onm spaced Shockleys; dislocations and their Burgers vector lie in the growth interface. For NiSi2 on (001) silicon, dislocations are rarely observed, however, a large concentration of ledges or facets are observed in an orthogonal network lying at the NiSi2 - (001)Si interface.It is argued thai the observed stress reduction of NiSi2 on (111)Si is due to concurrent dislocation multiplication and interfacial glide of the Shockley partials. Larger compressive stresses of NiSi2 on (111) silicon at the annealing temperature is attributed to the accumulation of the edge type Shockleys present in the NiSi2 phase. In contrast, the negligible decrease in stress during the formation of NiSi2 on (001) silicon is believed to result from the presence of sessile misfit compensating ledges which lie at the NiSi2-Si interface.
Formation of High-Quality Si/CoSi2/Si Double Hetero-Structures by Self-Aligned and Two-Step Molecular Beam Epitaxy
Authors: Miyao Masanobu , Ohshima Takashi , Nakamura Nobuo , Nakagawa Kiyokazu 
Published: March 2011

AbstractThe formation and application of Si/CoSi2/Si double heterostructures are comprehensively studied. A high-quality double heterostructure is formed by two-step molecular beam epitaxy of the Si over layer, i.e., low -temperature growth followed by high-temperature growth. The interfaces between CoSi2 and Si observed by cross-sectional transmission microscopy are atomically abrupt and smooth. In addition, a new fine patterning method of CoSi2 films using self-aligned and selective growth is developed. Finally, permeable base transistors (PBT) with high performance (gm=50 mS /mm) are fabricated using these new techniques.