bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface Reconstruction of MBE-Grown GeXSi1−x on Si(111)
Authors: Huang C. F. , Karunasiri R. P. G. , Park J. S. , Wang K. L. , Kang T. W. 
Published: March 2011

ABSTRACTSurface reconstruction during the molecular beam epitaxy (MBE) growth of GexSi1−x ( x = 0.2 - 1.0 ) film on Si(111) was studied using reflection high energy electron diffraction (RHEED). A series of reconstruction pattern transitions was observed due to the formation of strain layer and its relaxation. The critical thickness obtained using the thickness of the GexSil-x film at the transition of the reconstruction pattern agrees well with the previously reported values. The strain dependence of RHEED patterns for GexSi1−x film was substantiated by Raman scattering.
Study of Initial Stages of Heteroepitaxy Using Graded Thickness Samples
Authors: Biegelsen D. K. , Ponce F. A. , Krusor B. S. , Tramontana J. C. , Yingling R. D. 
Published: March 2011

ABSTRACTIn this paper we introduce the technique of graded thickness sample deposition to study the heteroepitaxial growth mechanisms of GaAs on Si. We can observe the continuous evolution from the initial clean surface, through nucleation, growth and coalescence of the deposited material.
Hetroepitaxy of GaAs by MBE on High Temperature Hydrogen Annealed Nominally (100) Oriented Silicon
Authors: Humphreys T. P. , das K. , Posthill J. B. , Parikh N. , Tarn J. , EL-Masry N. , Bedair S. M. , Chu W. K. , Wortman J. J. 
Published: March 2011

ABSTRACTHigh-quality GaAs epitaxial layers have been grown by molecular beam epitaxy on nominally (100) oriented silicon substrates annealed in a hydrogen-ambient at 1250 ? C. Growth procedure involves an in-situ thermal annealing step after the initial deposition of a thin GaAs buffer layer. Rutherford backscattering and channeling of 2.1 MeV He+ ions, interference optical and transmission electron microscopy have been used to characterize these layers. Comparative studies indicate that the epitaxial layers grown on hydrogen-ambient annealed substrates have a superior surface morphology and a lower interface disorder than those on chemically cleaned silicon (100) substrates. Microtwins, dislocations and antiphase domain boundaries are the predominant defects observed in these layers. A lower incidence of microtwins were observed in the hydrogen annealed substrates.
Effect of Atomic Structure at the Epitaxial CaF2 /Si(111) Interface on Electrical Properties
Authors: Batstone J.L. , Phillips Julia M. , Hunke E.C. 
Published: March 2011

ABSTRACTHigh resolution electron microscopy has been used to determine the atomic structure at the epitaxial CaF2 /Si(111) interface before and after a rapid thermal anneal. Direct Ca-Si bonding at the interface, with 8-fold coordinated Ca atoms is observed in as-grown layers. Fluorine is preferentially removed from the interface during a rapid thermal anneal leaving 5-fold coordinated Ca atoms. A dramatic improvement in the electrical properties of the interface is observed after annealing. The measured interface state density is reduced from ≳1013 cm−2 to ≲1011cm−2. This has been correlated with the removal of F from the interface. No evidence for direct F-Si bonding is observed.
MBE Growth and Properties of Fe Films on Lattice-Matched InxGa1−xAs Films
Authors: Farrow R. F. C. , Parkin S. S. P. , Speriosu V. S. , Wilts C. H. , Beyers R. B. , Pitner P. , Woodall J. M. , Wright S. L. , Kirchner P. D. , Pettit G. D. 
Published: March 2011

ABSTRACT.We report the growth and magnetic properties of epitaxial Fe films, prepared by MBE on films of GaAs and In0.2Ga0.8As, on GaAs (100) substrates. We find that the magnetic properties of the Fe films, which are in the thickness range 300-900Å have virtually no dependence on the nature of the buffer film between the GaAs substrate and the Fe film. In terms of FMR linewidth, 4πMs and anisotropy, the Fe films are of the highest quality yet reported. Values of exchange constant and surface anisotropies were derived from an analysis of spinwaves observed in the thickest films.
X-ray topography and EBIC studies of misfit dislocations in strained layer structures
Authors: Hamaguchi N. , Humphreys T. P. , Parker C. A. , Bedair S. M. , Jiang B-L. , Radzimski Z. J. , Rozgonyi G. A. 
Published: March 2011

ABSTRACTX-ray topography(XRT) and EBIC have been used to study the generation of misfit dislocations in strained layer structures. Two structures studied were GaAs1−yPy(y=0.15) film and SLS consisting of InxGa1−xAs(x=0.08) and GaAs1−y Py(y=0.16) layers. XRT and EBIC techniques gave consistent results for the behavior of dislocations. The value of the critical thickness for generation of misfit dislocations in the former was found to be few times larger than that in the latter. EBIC image showed that a SLS lattice matched to the substrate is effective in reducing defects originating from the substrate.
Stability Diagrams for Epitaxial Strained Layers
Authors: Tsao J. Y. , Dodson B. W. , Picraux S. T. 
Published: March 2011

ABSTRACTFor bulk materials, plastic deformation mechanisms and rates depend in a complex way on resolved shear stress and temperature, but can be succinctly described using the deformation mechanism maps pioneered by Ashby and Frost [1]. In this paper, we describe the use of such maps to demarcate the various stability and metastability regimes of single and multilayered strained epitaxial structures, and to interpret experimental work in the SiGe system.
In-Situ and High-Resolution Tem Observation of Interfacial Reactions in Metal-Silicon Multilayers
Authors: Holloway Karen , Do Khiem BA , Sinclair Robert 
Published: March 2011

ABSTRACTTitanium-silicon and molybdenum-silicon multilayers have been investigated in cross-section using a high resolution TEM with a point-to-point resolution of .22 nm. This resolution has allowed us to confirm the amorphous nature both of the intermixed layers which form at the metal-silicon interfaces on sputter deposition, and of the Ti-Si reaction product which forms at temperatures below which crystalline silicides nucleate.The bulk studies are complemented by in-situ annealing experiments in the high-resolution microscope. Phase reactions in the multilayers can be followed in real time, allowing direct observation of the formation of the amorphous alloy, the appearance of rows of Kirkendall voids, and the crystallization and growth of silicide phases.
The Effect of Ion Implantation on the Interdiffusion in Si/Ge Amorphous Artificial Multilayers
Authors: Park B. , Spaepen F. , Poate J. M. , Priolo F. , Jacobson D. C. , Pai C. S. , White A. E. , Short K. T. 
Published: March 2011

ABSTRACTAmorphous Si/Ge artificial multilayers have been implanted with Si and B at liquid nitrogen temperature, and partially ion mixed with Ar at different temperatures. In all cases, the square of the mixing length was found to be proportional to the dose. Annealing of Si-implanted samples showed that after relaxation the diffusivity appeared unaffected by the implantation process. Annealing of the B-implanted samples showed an enhancement of the diffusivity at the higher dose. The diffusive component of the square of the mixing length in the Ar-ion mixed samples has an Arrhenius-type temperature dependence, with an activation enthalpy of 0.22 eV.
Stability and Crystallization of Amorphous Semiconductor Multilayers
Authors: Persans P. D. , Ruppert A. F. , Abeles B. 
Published: March 2011

ABSTRACTWe discuss recent measurements of relaxation, interdiffusion and crystallization in amorphous hydrogenated semiconductors and insulators prepared as periodic multilayers. The stability of multilayer structures depends upon temperature, repeat distance and the nature of the materials. Crystallization of amorphous silicon in amorphous silicon/amorphous silicon dioxide layers is inhibited when the silicon thickness is reduced below 20 nm.
The Effect of Interfacial Disorder on the X-Ray Diffraction of Superlattices
Authors: Locquet J. P. , Neerinck D. , Sevenhans W. , Bruynseraede Y. , Homma H. , Schuller Ivan K. 
Published: March 2011

ABSTRACTWe have generalised our x-ray diffraction results from amorphous/crystalline multilayers, to include random interfacial disorder of a gaussian type. A general relation is obtained which can be applied to both crystalline/crystalline and crystalline/amorphous multilayers. This gaussian fluctuation or “roughness” can strongly reduce the long-range atomic order along the growth direction of the multilayer. Using classical structure factor calculations, we simulate the evolution of x-ray patterns as a function of the fluctuation amplitude, the superlattice wavelength, and the interatomic distances. Applying this model to the crystalline/crystalline case we fit the experimental Nb/Cu data, deduce a fluctuation amplitude of about 0.4 Å, and relate it to the lattice mismatch between Nb and Cu. For crystalline/amorphous systems (Pb/Ge) this amplitude can be significantly larger (2 Å).
Solid-Phase Amorphization in Layered Metal/Silicon thin Films
Authors: Nathan Menachem 
Published: March 2011

ABSTRACTA general scheme for determining which metal-Si systems undergo solidphase amorphization (SPA) upon rapid thermal annealing is presented and used to investigate Ni-Si, Ti-Si, V-Si, Co-Si and Cr-Si reactions. SPA occurs only in the first three systems. With the glaring exception of Co-Si, the results agree with the thermodynamic predictions of SPA in systems in which the free energy of a glassy phase is significantly lower than the free energy of the separate components. The amorphization may also be influenced by the diffusing species and contamination. Following SPA, the first crystalline compound is determined by nucleation kinetics.
Photon-Controlled Growth of Multilayered Structures
Authors: Lowndes Douglas H. , Geohegan D. B. , Eres D. , Mashburn D. N. , Pennycook S. J. 
Published: March 2011

ABSTRACTPulsed ArF excimer laser (193 nm) photolysis has been used to deposit entirely amorphous and mixed amorphous/polycrystalline superlattice structures containing Si, Ge and Si3N4. High resolution in situ optical reflectivity measurements were used to monitor and/or control deposition. Transmission electron microscope cross-section views demonstrate that amorphous superlattice structures having highly reproducible layer thicknesses (from about 50 to several hundred A), and sharp interlayer boundaries, can be deposited at low substrate temperatures under laser photolytic control.
Ellipsometric, Magneto-Optic, and Magnetic Properties of Sputtered Rare Earth-Transition Metal Multilayers
Authors: Tiwald Thomas E. , Woollam John A. , Shan Z. S. , Sellmyer D. J. 
Published: March 2011

ABSTRACTEllipsometric and magneto-optical properties of amorphous Dy (3.5 Å) and amorphous Fe (25 Å to 12.5 Å) multilayers were investigated over the spectral range from 3000 Å to 8000 Å in magnetic fields to 0.21 Tesla. In this range of layer thickness the magnetic anisotropy is vertical. Kerr rotations, θk, were weakly spectrally dependent, and as large as 0.1 degrees. The diagonal and off-diagonal elements of the optical dielectric response function were determined over the full spectral range, and were found to be dependent on iron layer thickness.
Hydrogen Bonding in Low-Gap A-Si,Ge:H,F Superlattices
Authors: Conde J. P. , Hager G. , Wagner S. 
Published: March 2011

ABSTRACTThe integrated absorption of the Si-H, Ge-H and Si-H2 IR stretching modes were measured for three series of superlattices where: a) the well to barrier thickness ratio was kept constant while the period was varied; b) the barrier thickness was kept constant while the well thickness was varied and c) the well thickness was kept constant while the barrier thickness was varied. The dark (σd) and photo (σph) conductivities, the photoconductivity exponent γ and the activation energy of the dark conductivity Ea were measured perpendicularly to the plane of the layers for series a) and b). Structural changes induced by sandwiching were documented by IR absorption and correlated with the optoelectronic properties of the thin films.
Atomic Arrangements in Short period MO-GE Multilayers Determined by X-Ray Anomalous Scattering and EXAFS
Authors: Wilson Lane , Bienenstock Arthur 
Published: March 2011

ABSTRACTStudies of atomic arrangements in amorphous and crystalline, short period Mo-Ge multilayers using synchrotron radiation X-ray diffraction (transmission and reflection), supplemented by EXAFS, are described. Differential anomalous scattering and EXAFS were utilized to determine the environment of each species. Intermixing, as well as a BCC epitaxial Ge structure, are among the observed structural characteristics. A wide range of structural variations is present indicating that specification of the layer thicknesses or composition profile alone is insufficient for characterization of the multilayers.
Transition Metal Excited States in Silicon
Authors: Kleverman M. , Olajos J. , Grossmann G. , Grimmeiss H. G. 
Published: March 2011

ABSTRACTRecent absorption and photoconductivity studies of deep transition-metal impurities in silicon are discussed, with emphasis on optical transitions from the deep ground state to shallow Coulomb excited states. The P3/2 line spectra of the deep Au and Pt acceptors closely resemble those of group II acceptors in silicon, whereas the P1/2 lines show resonance effects due to interaction with the valence band continuum. Behavior under uniaxial stress is compatible with D2d or C 2y point-group symmetry for the Au and Pt acceptors. A line spectrum in g-dopes Si can be attributed to excitations to shallow donor states since the phononassisted Fano resonances involve characteristic inter-valley phonons. Both the Ag donor spectrum and the corresponding Au spectrum are dominated by excited s-state transitions. Thus, the traditional fingerprint of a donor in silicon, i.e. the effective-mass like p-state series, is missing or at best observed weakly
Interactions of Implanted Carbon with Oxygen and Nitrogen in Silicon
Authors: Stein H. J. 
Published: March 2011

ABSTRACTCarbon has been implanted into Si to overlap implanted concentrations of oxygen and nitrogen. Impurity incorporation and interactions produced by implantation at 50°C, and upon subsequent annealing to 900°C, were monitored by infrared absorption. Implantation with 0 and C introduces absorption bands for C-0 centers in addition to those for substitutional C, interstitial 0, and 0-vacancy centers. These centers are removed by annealing. The major effect of C in N-implanted layers is a suppression of absorption bands associated previously with N aggregates. There is, apparently, a strong interaction between C and displacement defects which can alter defect reordering and control the loss of C from substitutional sites.
A Study of the Ion Implanted Arsenic Tail in Silicon
Authors: Beck S. E. , Jaccodine R. J. , Filo A. J. , Irwin R. 
Published: March 2011

ABSTRACTSpreading resistance measurements, Rutherford backscattering spectroscopy, ion channeling, and deep level capacitance transient spectroscopy are used to study ion implanted arsenic in silicon and its tail region. The following comparisons of the furnace annealed samples are made: Electrically active profiles versus total concentration profiles, tail diffusion versus total implant diffusion, and substitutional fractions. These results are compared to currently accepted models for arsenic diffusion in silicon.
Transition Metals in Electrically active Sites after Incoherent Light Annealing of Boron-Doped Czochralski-Grown Silicon
Authors: Barbier D. , Remram M. , Zhu J. 
Published: March 2011

ABSTRACTTwo hole trap levels H(0.45) and H(0.29) with properties close to those of metal-related defect states were found in virgin or implanted CZ silicon substrates submitted to a short duration Rapid Thermal Annealing (RTA) around 1000 °C. These hole trap levels were assigned to the presence of Fe or Cr in interstitial solution after RTA. Control experiments using chromium-diffused samples allowed to verify the quenching mechanism of chromium atoms in electrically active site during the annealing treatment, with a cooling rate-dependent concentration. After a subsequent low temperature annealing, the supersaturated interstitial solution of chromium evolves toward more stable defect configurations.
Hydrogen in Silicon
Authors: Corbett J. W. , Lindström J. L. , Pearton S. J. 
Published: March 2011

ABSTRACTWe summarize the recent results in hydrogen passivation in silicon, including presenting comprehensive diffusion profiles, i.e., profiles in floating zone n-type and p-type silicon vs resistivity. Domination of hydrogen diffusion by impurity trapping is clearly indicated for part of the profile in low resistivity p-type Si. Also mentioned are the current models of hydrogen passivation of dangling bonds, shallow acceptors, shallow donors, and hyper-deep defects.
Hydrogen Neutralization of Chalcogen double donor Centers in Single-Crystal Silicon
Authors: Pensl Gerhard , Roos G. , Stolz P. , Johnson N. M. , Holm C. 
Published: March 2011

ABSTRACTChalcogen (S,Se,Te) -doped silicon samples were hydrogen neutralized by different passivation techniques. The electrically active double-donor densities were determined by DLTS measurements. DLTS spectra reveal that both donor levels recover simultaneously. The activation energy for re-activation of neutralized isolated and pure pair sulphur double-donors is Ea(So/+) = 2,13 ± 0,15 eV and Ea(S2o/+) = 2,1 ± 0,15 eV, respectively.
Redistribution of Implanted Hydrogen in p+ GaAs(Zn) and n+ GaAs(Si) Crystais
Authors: Zavada J. M. , Wilson R. G. , Nova S. W. , Von Neida A. R. , Pearton S. J. 
Published: March 2011

ABSTRACTIn order to gain a better understanding of hydrogen in GaAs crystals, a Zn doped p+ GaAs wafer has been implanted with 300 keV protons (H) to a fluence of 1E16/ain and portions of the wafer have been furnace annealed at temperatures up to 600°C. The implanted H and the dopant Zn atomr were then depth profiled using secondary ion mass spectrometry (SIMS). The measurements show that the H redistributes itself in the p+ GaAs(Zn) in much the same manner as it does in n+ GaAs(Si). Movement of the implanted H begins with annealing at 200°C and proceeds rapidly with higher temperatures. However, based on the SIMS profiles, the diffusion coefficient for the H diffusing into the undamaged p+ GaAs(Zn) crystal appears to be considerably higher than that of H into n+ GaAs(Si). Electronic properties of the inplanted and annealed p+ GaAs samples have also been examined and correlated with the SINE profiles.
EL2 and the Electronic Structure of the AsGa—Asi Pair in GaAs: the Role of Jahn-Teller Relaxation
Authors: Baraff G. A. , Lannoo M. , Schluter M. 
Published: March 2011

ABSTRACTThe levels and excitation energies of the weakly interacting AsGa—Asi defect pair have been calculated using the model energy functional introduced by Baraff and Schluter, modified so as to allow Jahn Teller relaxation to distort the Asi away from the symmetry site. The physics underlying this calculation and the results emerging from it are described in this paper. We find that many previously unrelated experimental observations about EL2 are well accounted for by this model. However, there are still some controversial aspects of the fit of the model to the observed properties of EL2 which we cite as requiring further study.
Investigation of Midgap Defects in GaAs Induced By Heat-Treatment (EL2), Electron-Irradiation, and Plastic Deformation
Authors: Haga Toru , Suezawa Masashi , Sumino Koji 
Published: March 2011

ABSTRACTThermal behavior of midgap defects generated in GaAs by different procedures has been followed by means of optical absorption measurements at low temperature. EL2 centers existing in as-grown crystals or generated by thermal annealing at temperatures lower than about 1000°C, which are characterized by a perfectly quenchable absorption at a wavelength of 1.0 μm, are found to diminish at temperature higher than 1000°C. The generation kinetics of EL2 centers has been traced during isothermal annealing of a crystal in which grown-in EL2 centers have previously been eliminated by annealing at 1200°C. The result of an analysis with the use of simplified chemical rate equations favors the model that an EL2 center is composed of an As antisite and two Ga vacancies. Both quenchable and unquenchable absorptions are associated with the midgap defects induced by plastic deformation or electron -irradiation. Isochronal annealing reveals that such defects are not identical with EL2 centers that are found in an as-grown crystal even if they accompany the quenchable absorption.
Annealing of Grown-in Defects in Gaas
Authors: Dannefaer S. , Mascher P. , Kerr D. 
Published: March 2011

ABSTRACTDetailed analyses of positron lifetimes in GaAs have shown that an omnipresent type of defect acts as a shallow positron trap. This trap modifies the experimentally determined bulk lifetime to higher values and also influences the trapping rate into deep traps such as vacancies. It is suggested that the shallow trap likely is associated with boron. An annealing stage around 450°C is found.
Quantitative Raman Scattering from Acceptors in GaAs
Authors: Harrisz T. D. , Lamont M. G. , Seibles L. 
Published: March 2011

ABSTRACTRecent reports have demonstrated the possibility of probing acceptor concentrations in bulk semi-insulating GaAs by electronic Raman scattering using 1.06 μm radiation.1 The inefficiency of detectors in this spectral region severely limits sensitivity, precluding extension to epitaxial layers. We will discuss an approach using both 1.06 μm radiation to photo-neutralize acceptors, and a tunable dye laser to excite Raman scattering. Using a cooled CCD detector, an improvement in detection limit of 104 is realized. Comparison of Raman signals with infrared local mode measurements for samples with carbon concentrations from 1×1014 to 4×1015 cm-3 will be reported. The effect of 1.06 μm power density, dye laser wavelength, dye laser power, and sample fluorescence are included.
Effects of Surface and Bulk Defects in InP
Authors: Warren C. , Reinhardt K. , Singh A. , Lee Y. S. , Anderson W. A. 
Published: March 2011

ABSTRACTUndoped, n-type InP has been studied utilizing Au-oxide- InP metal-insulator-semiconductor (MIS) structures. Processing variations have included oxide growth techniques, and annealing of grown oxides. Annealing of the devices in N2 or N2 :H2 after oxide formation has reduced reverse saturation current density by up to a factor of 10 and increased barrier height from 0.45 to 0.65 eV. Annealing of the oxide increases refractive index due possibly to a densification or changed chemical structure. ESCA data reveals thin native oxides to be InP04 whereas thermally grown ones also contain P2 05 and In2 03. DLTS data reveals a dominant defect 597 meV below the conduction band.
X-Ray and Raman Studies of MeV Ion Implanted GaInAs/GaAs
Authors: Wie C. R. , Xie K. , Burns G. , Dacol F. H. , Pettit D. , Woodall J. M. 
Published: March 2011

ABSTRACTThe elastic strain in 2 MeV He ion-bombarded pseudomorphic or lattice-relaxd GaInAs is found to vary by 13% over tlhe beam dose range, 5x1012 - 5×1015 cm-2, with a minimum at 5×1013 cm-2. The data suggest a beam-induced annealing effect at lower doses and the build-up of radiation damage at higher doses, which are also indicated by the phonon line shift data. The phonon shift and the elastic strain in lattice-relaxed GaInAs, bombarded with 15 MeV Cl ions, are approximately the same as in an ion-bombarded bulk GaAs. The lattice mismatch in parallel constant decreases for a sample with a lower misfit and increases for a sample with higher misfit with increasing beam dose. The phonon shift in a pseudomorphic GaInAs bombarded with 15 MeV Cl ions is smaller than in the relaxed samples by a factor of two.