bluuebunny/crossref_metadata_2025_split huggingface dataset:
Detailed Kinetics Modeling of Indium Phosphide Films in Mocvd Reactors
Authors: Masi Maurizio , Cavallotti Carlo , Radaelli Guido , Carrà S. 
Published: April 2011

AbstractThe deposition kinetics of InP in MOCVD reactors is presented. The proposed chemical mechanism involves both gas phase and surface reactions. The fundamental hypothesis adopted in deriving the mechanism was a dual site dissociative adsorption of the precursors on the growing surface. In any case, all the rate constants either were taken from the literature or estimated through thermochemical methods. In addition, the deposition reactor was simulated by means of a monodimensional model that accounts for the main reactor features through the boundary layer theory.
Composition and Structure of Vicinal Ge(100) Surfaces Exposed to Tertiarybutylarsine
Authors: Gan Shupan , Li Lian , Han Byung-Kwon , Hicks Robert F. 
Published: April 2011

AbstractGermanium (100) substrates, 9° off axis towards the [011] direction, were heated in 2.0 Torr tertiarybutylarsine and 97.0 Torr hydrogen for 30 min at 650°C, then transferred to an ultrahigh vacuum system and annealed at several temperatures between 400 and 700°C. The arsenic coverage remained constant at 1.0 monolayer during heating in vacuum to 400°C. Further heating to 700°C caused the As coverage to gradually fall to zero. A mixed domain (l×2)+(2×l) dimer-terminated surface was observed by scanning tunneling microscopy after annealing at 400 to 510°C. Between 510 and 580°C, a single domain (l×2) reconstruction was recorded that contained equally spaced terraces separated by steps four atomic layers in height. Above 600°C, a (2×l) Ge(100) surface was produced that contained uniform terraces separated by steps two atomic layers in height.
Nucleation Studies Of Zns And ZnO Growth By Chemical Bath Deposition (CBD) On The Surface Of Glass And Tin Oxide Coated Glass
Authors: Mcaleese John , O'Briena Paul 
Published: April 2011

AbstractWe have studied the initial stages of nucleation and growth of ZnS and ZnO on glass and tin oxide coated glass in chemical baths containing thiourea as a source of sulfide ions. The results are used to comment on strategies for the deposition of ZnS and related ternary materials.
Deposition Of Znte Thin Films By Close Spaced Sublimation: Structural And Electrical Studies
Authors: Goyal D. J. , Bilurkar P. G. , Thorat S. K. , Mate N. V. 
Published: April 2011

AbstractZinc telluride has the potential of being a low-cost, environmentally stable, lowresistance and easily manufacturable back contact for CdS/CdTe solar cells. Close Spaced Sublimation (CSS) technique is used to deposit thin films of ZnTe. The results are reported in this study.The effects of substrate temperature and film thickness on the structural properties of the deposited thin films are studied. X-ray diffractograms show that all the films prominently exhibit presence of (111) and (200) orientations. However, the degree of the preferred orientation changes as a function of the film thickness. Increase in film thickness reduces the preferential orientation.The as deposited ZnTe thin films, being that of p-type semiconductor, are highly resistive. In order to effectively use these as contact to CdS/CdTe solar cells, they are made more conductive by doping copper. The doping is effected by dipping the films in alcoholic solution of copper chloride, followed by air annealing at 200°C. The resistivity of all the doped films drops drastically in the initial 10 minutes of annealing. The extent of doping is controlled by varying the dipping time.The effects of substrate temperature, film thickness and doping, on the stoichiometry of the films, are studied using Atomic Absorption Spectroscopy (AAS).
Solution-Grown Cds Thin Films For Solar Cells
Authors: Shin Jae Heyg , Hyeun Seung Wook , Shin Sung Ho , Park Jung , Park Kwang Ja 
Published: April 2011

AbstractThin films of CdS were prepared from an solution containing Cd(Ac)2, NH4OH, NH4Ac and (NH2)2CS for solar cells. Growth rate of CdS films was increased with increasing temperature of reactive solution and with decreasing concentration of NH4OH. Optical transmittances were more than 60% independent with temperature and concentrations and was changed with thickness of CdS films. Grown films mostly showed the presence of polycrystallines with mixed cubic and hexagonal phases, but showed the hexagonal preferred phases in some growth condition. The resistivities of CdS were decreased by doping boron from 104 to 101 order(Ω - cm) and the critical amount of dopant was 5 × 10− .mol %
The Properties Of a-Si:H/c-Si Heterostructures Prepared By 55 kHz Pecvd For Solar Cell Application
Authors: Budaguan B. G , Aivazov A. A. , Sherchenkov A. A. , Blrjukov A. V , Chernomordic V. D. , Metselaar J. W. 
Published: April 2011

AbstractIn this work a-Si:H/c-Si heterostructures with good electronic properties of a-Si:H were prepared by 55 kHz Plasma Enhanced Chemical Vapor Deposition (PECVD). Currentvoltage and capacitance-voltage characteristics of a-Si:H/c-Si heterostructures were measuredto investigate the influence of low frequency plasma on the growing film and amorphous silicon/crystalline silicon boundary. It was established that the interface state density is low enough for device applications (<2.1010 cm−2). The current voltage measurements suggest that, when forward biased, space-charge-limited current determines the transport mechanism in a- Si:H/c-Si heterostructures, while reverse current is ascribed to the generation current in a-Si:H and c-Si depletion layers.
Low Temperature Growth of Crystalline Silicon Thin Films by ECR Plasma CVD
Authors: Wang Licai , Reehal H S 
Published: April 2011

AbstractCrystalline silicon films have been deposited on silicon and metal-coated coming 7095 glass substrates at temperatures of 280 ˜ 680°C by electron cyclotron resonance (ECR) plasma assisted chemical vapor deposition (PACVD) using an ultrahigh vacuum chamber and SiH4 as the feedstock. X-ray diffraction (XRD), Raman spectroscopy, Rutherford backscattering (RBS) and secondary ion mass spectrometry (SIMS) have been used to characterize the films. At temperatures of ˜280 °C, the as-grown films are microcrystalline with crystalline fractions between 50–97%. From XRD patterns, randomly oriented crystalline silicon grains were clearly present in the films with the grain sizes estimated to be between 170 – 370Å. As the growth temperature is increased to 470°C, epitaxial growth on silicon is observed at growth rates of 240Å/min without bias or hydrogen plasma treatment before film growth. N-type doping of the layers has been achieved using PH3 as the doping gas and solar cells with ECR grown emitters fabricated on 15μm thick p-type epilayers on p+ substrates.
Impact Excitation And Auger Quenching Processes In Er Doped Light Emitting Si Devices
Authors: Franzo' G. , Priolo F. , Coffa S. 
Published: April 2011

AbstractA detailed investigation of the Auger non radiative de-excitation processes, which compete with the radiative emission of Er in Si, will be presented. This process, in which the energy released by the Er de-excitation is transferred to free carriers, is demonstrated to be extremely efficient and characterized by an Auger coefficient CA˜4.4×l0−13 cm3/s. This Auger process and an efficient incorporation method have been used to improve the performances of Er implanted light emitting diodes. It will be shown that by exciting Er within the depletion region of reverse biased p+-n+ Si diodes in the breakdown regime, it is possible to avoid Auger quenching and to achieve high efficiency. Moreover, at the switch off of the diode, when the depletion region shrinks, the excited Er ions become suddenly embedded within the neutral heavily doped region. In this region Auger de-excitation with free carriers sets in allowing to modulate the light signal at frequencies as high as a few MHz.
Light-Emitting Si:Er:O Diodes Operating In The Avalanche Regime
Authors: Sobolev N. A. , Emel'yanov A. M. , Gastev S. V. , Khakuashev P. E. , Nikolaev Yu. A. , Trishenkov M. A. 
Published: April 2011

AbstractElectroluminescence (EL) characteristics of avalanching diodes fabricated by Er and O co-implantation and subsequent annealing have been studied. Distribution of Er3+-related EL at 1.538 μm was found to be uniform over the device area at 300 K. Saturation of the Er-related EL intensity is achieved under the avalanche regime at current density one order of magnitude lower than that under the tunnel regime. An EL decay is less than 10 μs (being time response of our detector) after the diode turned off the avalanche regime.
Electroluminescence Studies Of Si Bulk Materials Using Al-Si Schottky Diodes
Authors: Du Chun-Xia , Ni Wei-Xin , Joelsson Kenneth B. , Shen Guang-Di , Hansson Göran V. 
Published: April 2011

AbstractElectroluminescence (EL) of Si bulk materials has been studied using lowly doped substrate with two Al-Si Schottky contacts. By applying a forward bias on the structure, the intense light emissions at 1.094 eV due to the TO-phonon assisted recombination was obtained at 40 K while other TA- and 2TO-associated transitions were also observed. The Si-TO EL peak persists up to RT with a radiative decay of ∼ 5 μs. EL emission mechanisms of these Si Schottky diodes are discussed based on temperature dependent- and injection current-dependent EL measurements.
The Oxidation Behavior of Silicon Nanocrystals in the Submonolayer Region
Authors: Diener J. , Ben-Chorin M. , Kovalev D. I. , Polisski G. , Koch F. 
Published: April 2011

AbstractFourier transform infrared spectroscopy is used to determine the time evolution of oxygen incorporation onto the surface of silicon nanocrystals. Oxygen concentrations up to one monolayer are investigated. The temporal progress of surface oxidation of Si nanocrystals in porous silicon shows a linear dependence on the square root of the oxidation time. This is similar to the oxidation of bulk Si and mesoporous silicon.
Composition dependence of room temperature 1.54μm Er3+ luminescence from erbium doped silicon:oxygen thin films deposited by electron cyclotron resonance plasma enhanced chemical vapor deposition
Authors: Shin Jung H. , Kim Mun-Jun , Seo Se-Young , Lee Choochon 
Published: April 2011

AbstractThe composition dependence of room temperature 1.54 μ Er3+ photoluminescence of erbium doped silicon:oxygen thin films deposited by electron cyclotron resonance plasma enhanced chemical vapor deposition of SiH4 and O2 with concurrent sputtering of erbium is investigated. The Si:O ratio was varied from 3:1 to 1:2 and the annealing temperature was varied from 500 to 900 °C. The most intense Er3+ luminescence is observed from the sample with Si:O ratio of 1:1.2 after 900 °C anneal and formation of silicon nanoclusters embedded in SiO2 matrix. High active erbium fraction, efficient excitation via carriers, and high luminescence efficiency due to high quality SiO2 matrix are identified as key factors in producing the intense Er3+ luminescence.
Silicon-Based Optoelectronics
Authors: Buchal Ch. , Löken M. , Siegert M. 
Published: April 2011

AbstractThe potential of silicon-based designs for various optoelectronic functions is discussed. Sibased light detectors are the most advanced, especially in the form of metal-Si-metal (MSM) photodetectors. They use Si band to band absorption for visible light and Schottky-barrier emission for the infrared (IR). The different light sources show rapid progress, but still face challenges to reach a quantum efficiency of 10−2. In addition to the intrinsic silicon based designs, some new Si breadboard concepts are shown: especially for waveguides, modulators and all-optical amplifiers, it may be advantageous to add entirely different materials (polymers, glasses, BaTiO3 or Al2O3) onto the Si wafer.
Optical Characterization of As2Te3 Films for for Optical Interconnects
Authors: Globus T. R. , Gaskill D. K. , Groshens T. 
Published: April 2011

AbstractAbsorption coefficient and refractive index measurements of stoichiometric As2Te3 thin films grown on Si and KBr substrates are presented. The films were grown by an organometallic deposition process where the sources for both As and Te react at reduced pressures and temperatures to produce stoichiometric films in the presence of a surface; no growth occurs otherwise. Films were grown at 300 and 373 K and had a thickness range of about 0.2–1.2 μm. The refractive index was sample independent and had strong dispersion near the optical gap, rapidly increasing from the value of 3.8 at 1.5 μm as the wavelength decreases. An interference technique was utilized to measure the absorption of the films since interference effects and substrate absorption bands hindered the application of conventional optical transmission techniques. The optical gaps, obtained from Tauc plots, were in the range 0.83–0.95 and the results confirm that the As2Te3 films behave as noncrystalline semiconductors, being either amorphous or partially crystalline. Amorphous films on Si had absorption in the range of optical transparency comparable to that of the substrate, films on KBr substrates had much higher absorption.
Beyond-The-Roadmap Technology: Silicon Heterojunctions, Optoelectronics, and Quantum Devices
Authors: Seabaugh Alan , Lake Roger , Brar Bobby , Wallacet Robert , Wilk Glen 
Published: April 2011

AbstractThe roadmap for silicon device technology has been drawn, extending to the year 2010, and featuring a CMOS transistor with a gate length of 0.07 μm [1]. Beyond this point, silicon heterojunctions could provide a means to further device scaling. Silicon heterojunctions could also bring new devices to the silicon substrate including light emitters and detectors, and resonant tunneling diodes (RTDs). Today SiGe/Si and SiGeC/Si heterojunctions are receiving the greatest attention, but heterojunctions now being developed to realize silicon RTDs are increasing the heterojunction options for silicon-based quantum-well and optical devices. Here we outline the fundamental device requirements for silicon optical and tunneling devices and describe progress on silicon heterojunction development towards demonstration of silicon-based RTDs. Materials now under study include, ZnS, crystalline oxides and nitrides; new processes could provide methods for forming crystalline materials over amorphous barriers.
Modeling of the Surface Annihilation of Excess Self-Interstitials Generated by Gold Diffusion into Silicon
Authors: Stolwijk N. A. , Lerch W. , Giese A. 
Published: April 2011

ABSTRACTBased on the kick-out mechanism, we have modeled the time evolution of the Si self-interstitial supersaturation during gold diffusion from evaporated surface layers into silicon substrates. The model comprises a limited annihilation velocity υI of self-interstitials at the Si surface, which accounts for the gradual increase of the Au boundary concentration observed during rapid thermal annealing at higher temperatures and furnace annealing at lower temperatures. Experimental data were fitted by computer simulation of the Au diffusion process. An approximate analytical expression describing the increase of the Au boundary concentration with time is also given. We obtain υI 1.35 × 1011 exp(−3.91 eV/kBT) ms-1 for gold-covered {100}-oriented Si surfaces between 845 °C and 1119 °C.
Gold Diffusion in Silicon During Gettering by an Aluminum Layer
Authors: Joshi Subhash M. , Gösele Ulrich M. , Tan Teh Y. 
Published: April 2011

ABSTRACTPrevious modeling of Al gettering of Au in Si indicated that, for an Al gettering layer placed on one surface of a Si wafer, Au will be gettered from both surface regions of the wafer to progressively greater depths with time. This is because, in Si, Au is a substitutional-interstitial (Aus-Aui) species with its diffusion governed by the kick-out mechanism which is mediated by Si self-inter-stitials (I). During gettering by the Al-Si liquid at one wafer surface, Aus atoms change over to Au atoms to rapidly migrate out of Si into the liquid. The changeover process consumes I. At the two wafer surface regions, the consumed I will be quickly replenished, while in the wafer interior an I undersaturation develops which hinders the Aus-Aui changeover and hence the gettering process. Experimental evidences which confirm the predictions have been obtained. Au was indiffused into a FZ Si wafer at 950°C for 16 hr. After removing the Au source and etching, samples from the in-diffused wafer were annealed at 1000°C without or with an Al layer on one surface. For samples without Al, there is no change in the net Au content, while the U-shaped indiffused profile becomes flatter. For samples with an Al layer, both wafer surface region Au concentrations were significantly decreased in 30 min while the wafer interior Au concentrations decreased only after annealing for longer times. The model predictions, the experimental results, and the implications on Si self-diffusion parameters will be discussed.
Robust Reaction-Transport Models of Movpe Reactors
Authors: Theodoropoulos C. , Moffat H. K. , Mountziaris T. J. 
Published: April 2011

ABSTRACTA simple gas-phase and surface kinetic model describing the Metalorganic Vapor Phase Epitaxy (MOVPE) of GaAs from trimethyl-gallium (TMG) and arsine has been extracted from reported reaction mechanisms through sensitivity analysis. This model was coupled with fundamental descriptions of the flow, heat and mass transfer in MOVPE reactors. All the uncertainties of the model were lumped into the two rate constants of the surface growth reaction. Finite element simulations of GaAs growth in a rotating-disk MOVPE reactor reported in the literature were used to fit the two unknown rate constants. Without any adjustment, the model could predict observed growth rates at higher susceptor rotational rates. A more serious robustness test was the fully coupled 2-D simulation of GaAs growth in a horizontal MOVPE reactor by using a state-of-the-art code (MPSalsa) developed at Sandia National Laboratories. The model predicted observed growth rates reasonably well in 2-D fully coupled simulations of flow, heat and mass transfer. Further development of the kinetic model by testing different kinetic scenaria in 2- and 3-d simulations and by using data obtained at kinetically-limited growth conditions is planned in order to develop a reactor-independent simulator of the MOVPE of GaAs. Such a model will be essential for the development of a conceptual virtual MOVPE reactor, which can be used for reactor design, optimization and model-based control.
A Theoretical Study on the Fundamental Chemical Reactions in Titanium Plasma-Enhanced CVD
Authors: Tsuda K. , Watanabe K. , Ohshita Y. , Takada T. 
Published: April 2011

ABSTRACTThe important intermediates in the Ti plasma-enhanced CVD using TiCl4/Ar/H2 are investigated by ab initio molecular orbital (MO) calculations. From the experimental point of view, it is pointed out that'TiCls is a key species for the Ti deposition reaction. So, its reactivity with the Si and SiO2 substrates is estimated theoretically from the stabilization energy. The difference of the stabilization energies of TiCl3 between them, which is 12.3kcal/mol in Hartree-Fock level calculations with using the on-top deposition reaction model, indicates a longer existing time by the factor of 102 on SiO2 than on Si. In addition to these calculations, the stabilization energies on the suicide substrates are also calculated and compared with the results on the Si and Si02 substrates. But other reaction paths may have to be considered because the growth rates of Ti thin films onto between Si and SiO2 don't necessarily coincide with the tendency of calculated results.
An Atomic-Scale Derived Continuous Approach for the Anisotropic Etching
Authors: Moldovan N. , Nedelcu S. , Amon H. C. 
Published: April 2011

ABSTRACTStarting from the Ising model for the bond-breaking algorithm associated to the problem of anisotropie etching of crystals, a method is used to write the discrete master equation for etching normally to indefinite large planes. This equation links the values of the absence probabilities for bonds placed in neighbouring lattice planes and can be transformed to describe a continuous spatial field of probabilities. The method allows the calculation of the etching rate angular diagrams. Examples are shown for several orientations and sets of parameters governing the bond-breaking scheme at atomic level. Comparisons with experimental results are provided.
Modeling and 2D Numerical Simulation of Transient Phenomena in Floating Body Soi Mosfets
Authors: Ionescu A. M. , Chaudier F. , Chovet A. 
Published: April 2011

ABSTRACTThis paper presents a numerical-simulation-based investigation of drain current transients in floating body partially and fully depleted n-channel SOI MOSFETs. For both Zerbst-type and overshoot transients, analytical models are developed and validated. An original contribution concerns the detailed study of drain and source junction influences on the transient regime.
Monte Carlo Studies for Strong Correlations in Hubbard-Type Models
Authors: Heeb E. S. 
Published: April 2011

ABSTRACTThe tight-binding model with repulsive Hubbard interactions represents an ideal prototype for the study of strong correlations. While exact numerical methods have been used with some success, they are typically limited by the size of the clusters that can be investigated or by the temperatures that can be reached. Variational methods, on the other hand, often require considerable advance knowledge of ground-state properties. The method presented here alleviates this problem by augmenting the variational approach with a scheme similar to Lanczos iterations thus bridging the gap between exact diagonalization and variational approaches. For the t-J model, the low-energy effective Hamiltonian of the Hubbard model, material properties like broken translational invariance or superconducting correlations are then investigated and a region of stability of a superconducting phase is found.
On-Site Correlation in Narrow Band Materials
Authors: Manghi F. , Bellini V. , Rontani M. , Arcangeli C. 
Published: April 2011

ABSTRACTWe present the results of a recently developed approach where the interplay between the itinerant and localized character of electrons in narrow band materials is described by adding on-site correlation effects to a realistic band calculation: the single particle band states are treated as mean field solutions of a multi-orbital Hubbard Hamiltonian and the many-body term associated with localized e-e interaction is described in a configuration-interaction scheme. Quasi-particle states of nickel and CuGe03 have been calculated and compared with spectroscopical results.
Environment-Dependent Tight-Binding Potential Model
Authors: Wang C. Z. , Pan B. C. , Tang M. S. , Haas H. , Sígalas M. , Lee G. D. , Ho K. M. 
Published: April 2011

ABSTRACTWe have developed a tight-binding model which goes beyond the traditional two-center approximation and allows the tight-binding parameters to scale according to the bonding environment. Our studies show that this environment-dependent tight-binding model improves remarkably the accuracy and transferability of the potential to describe the structures and properties of higher coordinated metallic systems in addition to those of low coordinated covalent systems.
Electronic Structure and Transport in Non Periodic Systems: New O(N) Methods
Authors: Mayou D. , Turchi P. E. A. , Roche S. , Julien J. P. 
Published: April 2011

ABSTRACTThe mathematical theory of orthogonal polynomials and continued fractions provides efficient tools, via the recursion and related methods, for calculating diagonal elements of Green's function of tight-binding Hamiltonians. We present two recent generalizations of this formalism. The first one allows the calculation of conductivity and other linear response coefficients. The second one provides a new approach to the solution of mean-field theories of alloys. In particular it is shown that the self-consistent CPA equations can be easily solved, through a real-space calculation, for multi-component alloys based on periodic or non periodic lattices.