bluuebunny/crossref_metadata_2025_split huggingface dataset:
Shallow Donor Centers in Erbium-Implanted Silicon Subjected to High-Temperature Annealing
Authors: Emtsev V.V. , Poloskin D.S. , Sobolev N.A. , Shek E.I. 
Published: April 2011

AbstractConsideration has been given to production processes of shallow donor centers formed in silicon after implantation of erbium ions or co-implantation of erbium and oxygen ions followed by annealing at 700° and 900°C. Analysis of the experimental data obtained in this work made it possible to put forward some suggestions concerning the nature of these defects.
Radioactive Isotopes In Photoluminescence Experiments: Identification Of Defect Levels
Authors: Magerle R. 
Published: April 2011

AbstractThe characteristic life-times of radioactive isotopes can be used to label and identify defect levels in semiconductors which can be detected by photoluminescence (PL). This technique is illustrated with three examples: ZnS doped with radioactive 65Zn by neutron irradiation and GaAs doped with radioactive 111In by ion implantation. Finally we report that doping GaAs with radioactive 71As which decays to stable 71Ga can be used to create GaAs antisites in GaAs in a controlled way and to identify their levels.
Low-Temperature Infrared Absorption Measurement For Oxygen Concentration and Precipitates In Heavily-Doped Silicon Wafers
Authors: Koizuka M. , Inaba M. , Yamada-Kaneta H. 
Published: April 2011

AbstractWe present a new IR absorption technique of measuring the dissolved interstitial oxygen concentration [Oi] and its reduction Δ [Oi] due to oxygen precipitation of the heavily-doped silicon crystal with doping level of about 1019 atoms/cm3. The method consists of the three steps: bonding the silicon wafer to a thick FZ silicon substrate by heat-treatment, thinning the wafer, and measuring the height of the 1136-cm−1 absorption peak of Oi at a temperature below 5 K. For a heavily doped wafer and the heavily doped substrate of an epitaxial wafer, we demonstrate examples of measuring the initial [Oi] and Δ [Oi] due to heat-treatment. Using this method, we investigate oxygen precipitation characteristics of the wafer heavily doped with boron. We found that the enhanced oxygen precipitation due to heavy boron-doping is expected if we perform preanneal at temperatures below 700°C.
Dislocation-Related Photoluminescence In Strain-Relaxed Si1−xGex. Buffer Layer Structures
Authors: Shum Kai , Mooney P. M. , Chu J. O. 
Published: April 2011

AbstractLow-temperature photoluminescence (PL) spectroscopy was used to study electronic states associated with threading dislocations (D lines) in strain-relaxed Si1−xGex layers. The structures investigated were grown by ultra-high vacuum chemical vapor deposition (UHV/CVD) at 550 °C and consist of an Si(001) substrate followed by a step-wise graded buffer layer followed by a thick uniform composition Si1−xGex layer. Variations in the PL intensity and peak position of the four D lines after isochronal annealing at temperatures between 600 and 800 °C have been measured. We show that the large energy shift of the D1 line is due to a change in the local band-gap energy at the dislocation core due to strain-driven diffusion of Ge away from the dislocation core with an activation energy of 2.4 eV.
Properties Of Inp Simultaneously Doped With Zinc And Sulfur Grown By Mocvd
Authors: Alavanja C. M. , Pinzone C. J. , Sputz S. K. , Geva M. 
Published: April 2011

AbstractAs the p-type dopant most often used in metalorganic chemical vapor deposition (MOCVD) of Group III - Group V compound semiconductors, Zn presents problems in device design and performance because of its high diffusivity in these materials. While Zn diffusion into n-type layers such as InP:S has been observed frequently, there is little known as to the electronic and optical properties of the resultant material. We have grown InP samples by MOCVD which are doped with both Zn and S to levels as high as 3×1018 cm−3. These samples were analyzed by electrochemical C-V profiling, van der Pauw-Hall analysis, secondary ion mass spectroscopy (SIMS), and low temperature (10K) photoluminescence spectroscopy (PL). We have determined that good hole mobility is maintained in InP:Zn samples that are simultaneously doped with S up to a level of 4×1017 cm−3. PL analysis of co-doped samples shows peaks between 0.91 and 0.92 μm which are indicative of donor-acceptor transitions, and broad peaks with energy levels of approximately 1.0 μm which may be indicative of ZnS complexes or precipitates. SIMS analysis of Zn diffusion into Fe doped substrates shows that Zn diffusion is reduced in the presence of S in the lattice.
Effect Of The Carbon Acceptor Concentration On The Photoquenching And Enhancement Of The Piezoelectric Photoacoustic Signals Of Semi-Insulating Gaas
Authors: Fukuyama A. , Morooka Y. , Akashi Y. , Yoshino K. , Maeda K. , Ikari T. 
Published: April 2011

AbstractThe spectral and the time dependent piezoelectric photoacoustic (PPA) measurements under the continuous light illumination were carried out at 85 K to investigate nonradiative recombination processes involving EL2 defect levels in carbon doped semi-insulating (SI) GaAs. The decrease of the PPA signal due to the photoquenching effect of EL2 was observed for a short period of illumination of 1.12 eV. It was found that the photoquenching becomes drastic with increasing the carbon concentration. After fully photoquenching, the PPA signal increased again through a local minimum by the continuous light illumination and finally exceeded the initial value before illumination until the saturation level was reached. The deep donor level EL6 and its metastable state are proposed. EL6 level donates electrons to compensate a part of carbon acceptors after photoquenching. The nonradiative recombination through this level generates the PPA signal. The usefulness of the PPA technique for studying the nonradiative transition through deep levels in semiconductor is suggested.
High-Temperature Reorientation Of Distortions In The Excited State Of The VGaTeAs Complexes In n-Type GaAs
Authors: Gutkin A. A. , Reshchikov M. A. , Sedov V. E. 
Published: April 2011

AbstractWe have investigated polarization of photoluminescence from the VGaTeAs complexes in n-GaAs induced through resonant excitation by polarized light. Experimental data in temperature range from 77 to 240 K were described by classic one-dipole approximation within the model of the VGaTeAs complex subjected to the Jahn-Teller distortion in the ground and excited states. It is shown that depolarization of photoluminescence at temperatures over ∼ 120 K may be explained by concurrent action of i) thermal emission and back capture of holes bound to the complexes in the excited state and ii) reorientation of complex distortion during a life of this state. The model parameters have been estimated.
Behavior Of Fluorine In N-AlInAs Layers Under Bias-Temperature Stresses
Authors: Yamamoto Y , Hayafuji N. , Sato K. , Otsubo M. 
Published: April 2011

AbstractThe electrical degradation of AlInAs /GaInAs high electron mobility transistor (HEMT) due to the fluorine contamination is quantitatively explained through the comprehensive annealing experiments and bias-temperature tests. The thermal degradation rate is found to be mainly determined by the following electrochemical reaction of fluorine with donor species after the quite fast diffusion of fluorine into the AlInAs layer. It is also confirmed that the thermal degradation is stringently affected by the electric field resulting in the one-sided degradation near the anode. These findings are important knowledges to improve the reliability of AlInAs/GaInAs HEMT under the DC accelerated life test at high temperature.
First-Principles Calculations Of Diffusion Of Chlorine Atoms In GaAs
Authors: Ohno Takahisa , Sasaki Taizo , Taguchi Akihito 
Published: April 2011

AbstractThe properties of chlorine atoms in crystalline GaAs, such as stable configurations, migration paths, charge-state effects, and interaction with dopant atoms are theoretically investigated. The calculations are based on the local density functional theory using first-principles pseudopotentials in a supercell geometry. We determine the stable charge state of an isolated Cl atom as a function of the Fermi energy. When the Fermi level is situated at the top of the valence band of GaAs, the Cl atom occupies preferentially the bond-center site of a Ga-As bond in the positive charge state. The Cl atom diffuses through the GaAs crystal via a path in the region of high electron density, with a fairly large energy barrier. When the Fermi level is at the bottom of the conduction band, the lowest-energy configuration of the Cl atom is the tetrahedral interstitial site in the negative charge state and the bond center site is very slightly higher in energy. In Si-doped GaAs, the C1 atom occupies the tetrahedral interstitial site with the substitutional Si donor atom as a nearest neighbor, forming a neutral Cl-Si complex. The Cl-Si complex is weak and easily dissociates into the isolated C1 and Si atoms in GaAs. A comparison will be made between the behavior of Cl and F atoms in GaAs.
The Differences between the InyGa1−yAs/GaAs Interface and GaAs/InyGa1−yAs Interface in Superlattice over a InxGa1−xAs (x<y) Buffer Layer
Authors: Wang X.J , Zheng L.X , Xiao Z.B , Zhang Z.P , Hu X.W , Wang Q.M 
Published: April 2011

AbstractThe InyGa1−yAs/GaAs superlattice on InxGa1−x.As (x<y) buffer layer was grown by MOCVD. The well layer is under compressive strain and the barrier layer is under tensile strain. However, both layers do not exceed the calculated critical value based on the M−yAs interface was smoother than the InyGa1−yAs/GaAs interface; the Indium composition gradual region at the GaAs/InyGal1−yAs interface was narrower than that at the InyGa 1−yAs/GaAs interface; in InyGa1−yAs alloy layer, the Indium composition near the GaAs/InyGa1-yAs interface was higher than that near another interface. For the first time, we explained the composition profile in this kind of superlattice based on the indium segregation theory. A new strain relaxation model, in which the 30-degree and 90-degree shockley partial dislocations were taken into account under both tensile and compressive strains, was presented to explain the difference of the smoothness between the GaAs/InyGa1−yAs interface and the InyGa 1−yAs/GaAs interface.
The Effects Of Substitutional Alkaline Metals In Zinc Vacancy Of Zincselenide Single Crystals Grown By The Sublimation Method
Authors: Yoshino Kenji , Maeda Kouji , Fukuyama Atsuhiko , Akashi Yoshito , Imada Kiyohisa , Ikari Tetsuo 
Published: April 2011

AbstractThe photoluminescence measurements of alkaline metal doped zincselenide (ZnSe) single crystals were carried out to investigate how the impurity atoms substitute the intrinsic vacancy. Sample are grown by the sublimation method and the Li and Na with the concentrations of 0.1, 0.25 and 0.5 mol% were incorporated simultaneously. In the PL spectra with lower impurity concentrations, bound exciton lines of deep acceptor and donor-acceptor pair (DAP) bands were clearly observed accompanied by a weak free exciton line. Although the bound exciton lines becomes smaller with increasing the impurity concentration, the DAP band remains strong and its peak energy shift to lower energy side with the concentration. The decrease of the bound exciton lines is drastic for Li-doped sample than Na-doped sample. This indicates that Li atoms more easily occupy the Zn vacancies than Na.
Investigation Of Deep Energy Levels In II-VI Compounds
Authors: Castaldini A. , Cavallini A. , Fernandez P. , Fraboni B. , Piqueras J. 
Published: April 2011

AbstractDeep levels in II-VI compounds have been investigated to understand their role in the compensation mechanism and their influence on the material electrical and optical properties. The electrical properties have been studied by current and capacitance transient spectroscopy, while the optical properties have been studied by cathodoluminescence. We have focused our attention on the traps involved in the compensation process, such as centre A and the deep levels located near midgap.
Nondestructive Characterization Of The Surface Aging Of HgI2 Crystal
Authors: Yao H. , Erickson J. C. , James R. B. , Natarajan M. 
Published: April 2011

AbstractVariable angle spectroscopic ellipsometry (VASE) and atomic force microscopy (AFM) measurements have been employed to characterize the surface aging of HgI2 crystals. A surface model including top surface roughness and subsurface defects was established and studied by VASE analysis, as a function of real time, after the 10% KI chemical etching. In this model, the surface defects associated with the surface aging were modeled by the Bruggeman effective-medium approximation (EMA) as a HgI2/voids mixed layer. The relative 2-dimensional (2D) surface-defectdensities were monitored as the surface aging proceeds. The VASE measurements indicated that high surface aging rates were related to high initial effective 2D surface-defect densities. The AFM profile revealed increasing physical surface roughness as surface aging took place. The cleaved HgI2 crystal surface presented a smooth surface and the lowest surface aging rate, while the as-grown HgI2 surface also presented a very low surface aging. The HgI2 surfaces baked at elevated temperatures presented accelerated surface aging phenomena after a 30 min. baking.
Vacancies In Electron Irradiated 6H-SiC
Authors: Friessnegg T. , Dannefaer S. 
Published: April 2011

AbstractAnnealing of electron irradiated bulk n-type 6H-SiC has shown that neutral carbon vacancies and neutral silicon vacancies undergo a major reduction in concentration in the 20–200 °C temperature interval after which only slight changes occur up to 1200 °C. The experiments suggest that the positively charged carbon vacancy, detected by electron paramagnetic resonance, constitutes only a small fraction of all carbon vacancies.
Imaging Of Micropipes In Silicon Carbide Under High Field Stress
Authors: Gradinaru G. , Helmi M. , Khlebnikov Y. , Korony G. , Mitchel W. C. , Sudarshan T. S. 
Published: April 2011

AbstractA new technique for investigation of the electrical effects of micropipes in single-crystal 6H-SiC is presented. The setup allows the application of a parallel or normal electric field to MSM (metal-semiconductor-metal) test structures and the visualization of light emission sites in the test gap, including light activity underneath the metal contact. A special transparent metal [indium-tin-oxide(ITO)] was chosen for the metallic contacts. A map of micropipe locations was initially obtained at zero applied field using a laser scattering method. The initial map is compared with that of light emissions at different applied fields.Several tests on undoped and vanadium-doped (compensated) SiC, using NiCr/Au or ITO contacts, indicated the rapid activation of micropipes at relatively low fields in vertical MSM devices. A good match between the laser imaging map of micropipes at zero field and the map of field-induced light emission sites indicates that micropipes are the main current paths in vertical devices, carrying a large current density, and leading to light emissions and partial or total bulk breakdown of the test device.
X-Ray Topography Of A Single Superscrew Dislocation In 6H-SiC Through All {100} Faces
Authors: Vetter W. M. , Dudley M. 
Published: April 2011

AbstractMicropipes, the hollow cores of superscrew dislocations that lie along the c-direction in SiC single crystals, are quite deleterious to the performance of semiconductor devices. In the x-ray topography of longitudinal-cut samples of these crystals, topographs in the reflection (006) show dislocation image contrast associated with the superscrew dislocations lying along the c-axis of the crystal, which is also the direction of the dislocations' Burgers vectors. In the (110) reflection, whose g-vector is perpendicular to the c-axis and the dislocations' Burgers vector, there is also an image of the superscrew dislocation formed, albeit weaker than the corresponding image in the (006) reflection. This dislocation image is thought to represent stress components of the superscrew dislocation in directions perpendicular to the c-axis.In order to investigate the origin of these stress components, steps have been carried out to determine whether the dislocation image is anisotropic in all possible reflections where g={110}. To achieve this we have excised a hexagonal prism-shaped sample from a 6H-SiC wafer, 100μm wide, polished along the six {100} crystallographic faces, such that a single micropipe ran along the axis of the sample. This enabled x-ray topographs to be taken through each of these {100} faces
The Influence Of The Incorporation And Desorption Of Chn, Groups On The Defect Structure Of a-SiC:H Films
Authors: Friessnegg T. , Boudreau M. , Mascher P. , Simpson P.J. , Puff W. 
Published: April 2011

AbstractChanges in the defect structure in carbon rich a-SiC:H films deposited on various substrates using ditertiary butyl silane were investigated as a function of thermal treatment. Films grown at high deposition rates exhibit hydrogen trapped in voids. The incorporation of CHn, groups is thought to be the origin for these microvoids. With increasing annealing temperature the effusion of CHn, groups as determined by thermal desorption experiments promotes void growth which was studied using a variable energy positron beam. At annealing temperatures above 600 °C the films densify due to the breaking of C-H bonds and the formation of additional C-C bonds when the voids anneal out.
Coexistence Of Two Carbon Phases At Grain Boundaries In Polycrystalline Diamond
Authors: Shenderova O. , Brenner D. W. 
Published: April 2011

AbstractEnergies and structures for two models of <001> tilt grain boundaries in diamond have been calculated using a many-body empirical bond-order potential. The first model contains all four-fold coordinate atoms. The second model is a two-phase system in which a graphitic region connects the diamond grains. At selected misorientation angles we predict that the two-phase structures are energetically competitive with the sp 3 bonded structures when the width of the graphitic regions exceed 10–15Å.
Hydrogen-Induced Luminescent States In The Subsurface Region Of Homoepitaxial Diamond Films
Authors: Hayashi Kazushi , Watanabe Hideyuki , Yamanaka Sadanori , Sekiguchi Takashi , Okushi Hideyo , Kajimura Koji 
Published: April 2011

AbstractWe found the existence of hydrogen-induced luminescent states in the subsurface region of chemical-vapor-deposited homoepitaxial diamond films by means of cathodoluminescence (CL). A specific broad peak at around 540 nm is observed in both as-deposited diamond films and those treated by hydrogen plasma at 800 °C, but not in conventional oxidized films. The accelerating voltage dependence of the CL spectra indicates that the luminescent states related to the 540 nm peak exist in the surface region and decrease abruptly with increasing the depth from the surface, showing that the depth distribution of the states slightly depends on the hydrogenation duration. Although the 540 nm peak is not observed in the films hydrogenated at 500 °C, it appears once the films are irradiated by an incident electron beam. It indicates the existence of a metastable configuration of hydrogen or its complex forms in the diamond films hydrogenated at low temperatures and a relaxation occurs into a stable one which produces luminescent states by the electron-beam irradiation.
Low K Mesoporous Silica Films Through Template-Based Processing
Authors: Bruinsma P.J. , Hess N.J. , Bontha J.R. , Liu J. , Baskaran S. 
Published: April 2011

AbstractLow dielectric-constant mesoporous silica films were prepared by condensation of a silicate network around surfactant micellar structures. Adherent, porous films 0.5–1.0 μm in thickness, and containing an ordered assemblage of ≈2 nm diameter pores were synthesized by spin-coating water/ethanol-based solutions containing a silica precursor and surfactant template. In this paper, film deposition conditions are described, and film thickness, porosity, refractive index and dielectric constant measured by ellipsometry are presented. Using a coating solution containing tetraethyl orthosilicate (TEOS) and a cationic cetyltrimethylammonium chloride (CTAC) surfactant template, the film porosity and dielectric properties were controlled over a wide range by adjusting the CTAC/TEOS molar ratio. With the CTAC/TEOS ratio between 0.1 and 0.15, the pores were highly ordered in hexagonal arrays after heat treatment at 550 °C. With a CTAC/TEOS ratio of 0.21, films with a pore volume of ≈64% (≈36 vol% silica) could be synthesized. The measured index of refraction for these highly porous films at 500 nm wavelength was 1.16, indicating that these films are potentially useful as low K interlayer dielectrics.
PE-CVD of F-Doped SiO2 Thin Films Using Tetraisocyanatesilane and Tetrafluorosilane
Authors: Shirafuji T. , Sawada M. , Nakagami Y. , Hayashi Y. , Nishino S. 
Published: April 2011

AbstractSiO2 films have been prepared from tetraisocyanatesilane (TICS, Si(NCO)4) by using a conventional capacitively coupled RF(13.56MHz) plasma-enhanced CVD method. The films show poor water resistivity, which originates in inclusion of NCO in the films. This has been improved by mixing O2 to the source gas. SiO:F films have been prepared by mixing SiF4. The film with F concentration of 6at.% has shown dielectric constant of 3.3, resistivity of 3.6×1015Ωcm at 1MV/cm and break-down electric field of 7.7MV/cm. Infrared spectrum of the film have contained no noticeable OH peak even after exposing to the air for 2 weeks.
A Study Of Anisotropy Of Spin Cast And Vapor Deposited Polyimide Films Using Internal Reflection Techniques
Authors: Liberman Vladimir , Malba Vincent , Bernhardt Anthony F. 
Published: April 2011

AbstractWe have compared anisotropy of spin cast and vapor deposited polyimide (VDP) films, using internal reflection infrared spectroscopy. The films were deposited directly on the internal reflection element. We find that spin cast films are more anisotropic than their VDP counterparts, with the polyimide chains tending to align parallel to the substrate. Both films are found to contain more and less ordered regions. Within the ordered regions, the plane of the phenyl ring tends to align parallel to the substrate.
Fluorocarbon Films from Plasma Polymerization of Hexafluoropropylene and Hydrogen
Authors: Mountsier T. W. , Kumar D. 
Published: April 2011

AbstractFluorocarbon polymers exhibit excellent dielectric properties; however, their limited thermal and mechanical stability render them unsuitable for most interlevel dielectric applications. In this work we explore the plasma assisted deposition of fluorocarbon films from hexafluoropropylene (C3F6) and hydrogen in order to understand how the mechanical and thermal properties might be improved. Plasma activation and ion bombardment promote the formation of a crosslinked, amorphous film structure. Several process parameters were examined including temperature and rf driving frequency. The results demonstrate that crosslinked fluorocarbon polymers with enhanced mechanical strength can be produced from C3F6 in a plasma environment. Most of the films studied here had dielectric constants in the range of 2 to 2.5. Thermal stability (to 400 °C), however, was not achieved.