bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Structural and Electrical Characteristics of Extended Defects on GaAs Field Effect Transistors
Authors: Van Hove M. , De Raedt W. , De Potter M. , Van Rossum M. , Weyher J. L. 
Published: March 2011

ABSTRACTThe paper presents a systematic study of grown-in and process-induced defects on LEC GaAs substrates. Defects have been revealed by photoetching the wafers with diluted Sirti-like solutions after various processing steps. MESFET arrays have been processed on the wafers and a systematic mapping of the I-V characteristics has been performed. A correlation between various defect configurations and the FET threshold voltage shifts has been established.
New Defect Related Phenomena in Semiconductor Heterolayers and Superlattices
Authors: Capasso Federico , Beltram Fabio 
Published: March 2011

ABSTRACTRecent work on defect related phenomena in heterojunctions and quantum well structures is reviewed. These include situations in which quantum wells behave as deep traps and the use of shallow and deep centers as new tools for band structure engineering. Among the latter tunable band discontinuities and the artificial tailoring of superlattice states via δ-doping techniques are discussed.
Characterization of Defects in GaP, GaAs and GaAsl-xPx Electroluminescent Diodes by Transmission Electron Microscope
Authors: Hirata Mitsuji , Takeda Seiji , Fujii Katsushi 
Published: March 2011

ABSTRACTDislocations and some other lattice defects were observed in typical III-V semiconducting materials. The usefulness of electron microscopy is emphasized and some examples of characterizing the nature of lattice imperfections are presented here.
Spectroscopy of III–Vs Under Hydrostatic Pressure
Authors: Stradling R. A. 
Published: March 2011

ABSTRACTIn GaAs and InSb common residual contaminants introduce both shallow donor states and other levels normally resonant with the conduction band but taking their predominant character from higher conduction band minima. These states can be made to emerge into the forbidden gap by applying hydrostatic pressure. Judged by the measured pressure coefficients two sets of levels are closely tied to the L- and X-conduction band minima. At low temperatures the X-associated states show local relaxation effects and metastability (i.e., D(X) behaviour). Pressure experiments have also been performed with spike-doped GaAs both in single layer and in superlattice form. Shubnikov-de Haas peaks can be observed above 3T. Fourier analysis of these shows that up to six sub-bands can be occupied. The application of hydrostatic pressure of up to 20kbar dramatically increases the mobility of the electrons in the lowest sub-band by as much as an order of magnitude with smaller increases occurring the higher sub-bands. The increases in mobility arise from the diffusion of the silicon donors during growth. Localised donor states associated with the L-conduction band drop below the Fermi energy in the centre of diffused distribution of donors on the application of pressure and become neutralised. This reduction of ionised scattering centres affects the most confined electron states and thus the mobility of the lowest sub-band increases very substantially.
Characterisation of Epitaxial MBE and MOCVD GaAs DOPED with Donors or Acceptors Using FTIR Spectroscopy
Authors: Murray R. , Newman R. C. , Nandhra P. S. , Beall R. B. , Harris J. J. , Wright P. J. 
Published: March 2011

ABSTRACTEpitaxial layers of GaAs grown by MBE or MOCVD and doped with silicon impurities have been studied using FTIR spectroscopy. Vibrational modes are observed for Si(Ga), Si(As), Si(Ga)-Si(As) and a defect labelled SI-X. This latter defect appears to be responsible for the compensation effects found in some highly doped material. The Si(Ga) mode is modified in AlGaAs but understood in terms of a simple statistical model. Epitaxial GaAs layers doped with silicon or beryllium are passivated by exposing the samples to an RF hydrogen plasma which leads to the formation of Si-H and Be-H close pairs.
DX Centers in GaAs and AlxGal-x.As: Properties and Influence on Material and Device Characteristics
Authors: Mooney P. M. 
Published: March 2011

ABSTRACTThe DX center, the lowest energy state of the donor in AlGaAs with x > 0.22, is responsible for the reduced conductivity as well as the persistent photoconductivity observed in this material at low temperature. Extensive studies of the properties of this level and of its effects on the characteristics of some heterojunction devices are reviewed here. Recent measurements are presented showing that the characteristics of the DX center remain essentially unchanged when it is resonant with the conduction band (x < 0.22) and that, independent of other compensation mechanisms, the DX center therefore limits the free carrier concentration in GaAs to a maximum of about 2×1019 cm− 3.
Mechanisms of Doping-Enhanced Superlattice Disordering and of Gallium Self-Diffusion in GaAs
Authors: Tan T. Y. , Gösele U. , Marioton B. P. R. 
Published: March 2011

ABSTRACTRecently available Ga-Al interdiffusion results in GaAs/AlAs superlattices allow to conclude that Ga self-diffusion in GaAs is carried by triply-negatively charged Ga vacancies under intrinsic and n-doping conditions. The mechanism of the Si enhanced superlattice disordering is the Fermi-level effect which increases the concentrations of the charged point defect species. For the effect of the p-dopants Be and Zn, the Fermi-level effect has to be considered together with dopant diffusion induced Ga self-interstitial supersaturation or undersaturation. Self-diffusion of Ga in GaAs under heavy p-doping conditions is governed by positively charged Ga self-interstitials.
TEM Studies of Ordering in MOCVD-Grown (GaIn)P on GaAs
Authors: McKernan S. , Cooman B. C. De , Carter C. B. , Bour D. P. , Shealy J. R. 
Published: March 2011

ABSTRACTGaxIn(1−x)P epilayers grown on GaAs substrates by MOVPE, for different growth temperatures and values of x∼0.5, have been studied by electron microscopy. The results indicate that under certain conditions the ternary epilayer is ordered parallel to the (111) plane. Dark-field images obtained using the superlattice reflections reveal ordered domains of different orientations. High-resolution images have been obtained from the ordered domains. The structure of these domains is not perfect but contains many planar faults parallel to the growth surface.
Uniaxial Stress Studies of Optical Centres in Silicon
Authors: Davies Gordon 
Published: March 2011

ABSTRACTUniaxial stress perturbations have provided considerable data on the properties of optical centres in silicon. This paper reviews their uses in determining atomic kinetics and the symmetry of optical centres. Examples are given of the different effects of stress-induced interactions between states, and of the thermalisation of stress-split states. Uniaxial stresses are shown to be useful in grouping together similar optical centres, and in understanding the defect-induced widths of zero phonon lines and the vibronic properties of centres. At some optical centres, “internal” stresses can be used to contruct bound states from perfect crystal states.
Effects of Pre-Gate Oxidation Intrinsic Gettering Upon Thin Gate Oxide Integrity In High Carbon Content CZ Si
Authors: Hahn S. , Tung C. Y. , Lee J. , Tuomi T. , Partanen J. 
Published: March 2011

AbstractEffects of post-well drive intrinsic gettering (PWIG) upon the integrity of thin gate oxide in Cz Si wafers with carbon levels, Cs, ranged from 0.2 - ∼ 4 ppma were investigated. A 10 nm thick gate oxide capacitor was used to study its time-dependent breakdown characteristics and minority carrier lifetime. Our data have shown that PWIG cycles and/or carbon impurity affect both bulk oxygen precipitation and minority carrier lifetime, but not the oxide integrity.
Comparison of Low Temperature Methods for the Production of Silicon Dioxide Thin Films.
Authors: Baker Stephen D. , Milne W. I. , Taylor S. 
Published: March 2011

AbstractIn this paper we present a comparison of the physical and electrical properties of high quality insulating thin films of silicon dioxide produced at low temperatures by three methods; standard plasma enhanced CVD of silane/nitrous oxide, photo enhanced CVD of silane/nitrous oxide using a novel internal nitrogen discharge lamp, and oxygen plasma anodisation.The electrical and interface properties of the films, obtained from current-voltage and capacitance-voltage measurements are compared. The physical properties and composition of the films have been investigated by standard methods such as ellipsometry and p-etch rate, and spectroscopic techniques such as Auger, XPS, LIMA and Infrared absorption. The results of these investigations are reported.The effects of low temperature annealing on the film properties have been examined and the suitability of each of the fabrication techniques to a variety of applications is discussed.
The Role of Diatomic SiO in Dry Oxidation of Si
Authors: Raider Stanley I. , Walkup Robert E. 
Published: March 2011

AbstractThe interaction of O2(g) with clean Si(s) surfaces at high temperature and low pressure leads to an etching reaction, 1/2 O2(g) + Si(s) → SiO(g), which results in the evolution of SiO molecules from the surface. Above a critical O2 pressure, an oxide film SiO2(s) begins to grow. The evolution of diatomic SiO during the early stages of film growth may provide a mechanism to account for deviations from standard models of oxidation kinetics for thin oxides, and for the results of oxygen isotope tracer studies of oxide formation. In order to monitor the rate of SiO evolution, we have made in-situ measurements of the SiO concentration in the gas phase, using a laser-induced fluorescence technique. With this method, SiO(g) can be monitored in the furnace with good spatial resolution and a sensitivity limit of ˜ 106 molecules cm−3. Measurements of SiO evolution and the implications for oxide growth will be discussed.
The Oxygen Vacancy and The E1′ Center In SiO2
Authors: Bar-Yam Y. , Pantelides S. T. , Joannopoulos J. D. , Allan D. C. , Teter M. P. 
Published: March 2011

AbstractWe report parameter-free self-consistent calculations of structural properties for the oxygen vacancy in silicon-dioxide using new oxygen pseudopotentials and quantum molecular dynamics simulations. Results challenge the accepted identification of the oxygen vacancy with the paramagnetic E1′ center. Bonding of the adjacent silicon atoms occurs sufficiently strongly for all charge states to inhibit the asymmetric distortion which would be required for correspondence with the E1′ center.
Density Functional Based Studies of Oxygen Vacancies In Crystalline Silicon Dioxide
Authors: Pederson Mark R. , Harrison Joseph G. , Klein Barry M. 
Published: March 2011

AbstractWe have performed electronic structure studies on two neutral oxygen vacancies in crystalline silicon dioxide. The idealized beta-crystobalite structure has been used as a model for the host perfect crystal. The calculations have been carried out by representing the host-defect system as a large cluster of atoms which is properly. embedded into the host crystal, with a Gaussian orbital basis used to describe the electronic states of the host and defect systems. The local density approximation with and without the self-interaction correction has been used in these calculations.
Electrical Characteristics of Tisi2/n+-Polysilicon/Sio2/Si Mos Capacitors Stressed Under High Temperature Silicide Processing Conditions
Authors: Shenai K. , Piacente P. A. , Baliga B. J. 
Published: March 2011

AbstractDetailed electrical characteristics of TiSi2/n+-polysilicon/SiO2/Si MOS capacitors stressed under a variety of high temperature processing conditions is reported. These devices have ˜2000Å TiSi2 formed by a two-step thermal anneal on heavily POCl3doped polysilicon with thicknesses of 6 kÅ and 8 kÅ. These structures were capped with 8 kÅ of SiO2 and stressed in nitrogen at process temperatures in the range of 700° C to 1100° C. The electrical performance was evaluated in terms of I-V, C-V, Fowler-Nordheim tunneling, and SiO2/Si interface characteristics of MOS structures. A systematic degradation of the SiO2/Si interface was observed due to process limitations of TiSi2 at high Lemperatures.
LPCVD of Silicon Nitride Films From Hexachlorodisilane and Ammonia
Authors: Taylor R. C. , Scot B. A. 
Published: March 2011

AbstractHexachlorodisilane (Si2Cl6) has been used as an alternative to dichlorosilane and silane for growth of silicon nitride films. The films were grown at a pressure of 0.7 Torr at temperatures between 450° and 850°C. Growth rate data indicates a kinetically controlled deposition with an activation energy of 29.3 kcal/mole. Growth rates are substantially higher than those obtained from SiH2Cl2 under similar conditions, and the physical properties of the films are essentially the same. At the higher growth temperatures stoichiometric Si3N4 films with no detectable chlorine can be obtained when a NH3/Si2Cl6 ratio of 60 or greater is used.
Control of Bonded SiH in Silicon Oxides Deposited by Remote Plasma Enhanced CVD
Authors: Tsu D. V. , Parsons G. N. , Lucovsky G. , Watkins M. W. 
Published: March 2011

AbstractThis paper describes Optical Emission Spectrocopy (OES) and Mass Spectrometry (MS) studies of the plasma region in the Remote Plasma Enhanced Chemical Vapor Deposition (PECVD) of amorphous hydrogenated silicon (a-Si:H) and silicon oxide thin films. In Remote PECVD, only the O2/He mixture is plasma excited, silane is introduced into the deposition chamber well below the plasma region. Deposition of films has been studied over a wide range of relative He and O2flows, between 100% He and 100% O2. The incorporation of SiH in the oxides derives from the same mechanism as the deposition of a-Si:H, i.e., a metastable He induced fragmentation of silane.
Degradation of Micron-Sized Silicide Lines on Polycrystalline Silicon
Authors: Phillips J. Randall , Zheng Lung-Ru , Mayer James W. 
Published: March 2011

ABSTRACTThe thermal stability of silicide fine lines on undoped CVD polycrystalline silicon was investigated. Heat treatments were in vacuum at temperatures up to 950 ° C. We observed that fine silicide lines on undoped polysilicon degrade during vacuum annealing. Voids and hillocks are formed as silicon diffuses out from the fine grained poly-Si, undergoes long-range transport through the silicide, and recrystallizes into large grains. The phenomenon is similar to that seen previously in planar samples, but fine lines were found to degrade at lower temperatures and especially along line edges. Lines of two refractory metal silicides, TiSi2 and CrSi2, and one near-noble silicide, CoSi2 were examined.
Interactions of Polysilicon with Aluminum
Authors: Ottaviani G. , Tu K. N. , Nobili C. 
Published: March 2011

ABSTRACTIn-situ resistivity measurements togheter with Auger electron spectroscopy, MeV 4He+ backscattering spectrometry, scanning electron microscope and x-ray diffraction have been used to investigate interactions between Al films and CVD polycristalline silicon layers deposited on thermally grown SiO2 on silicon. A sharp and well defined increase in resistivity around 450 °C has been associated to the erosion of the polysilicon and growth of Si crystallites in the metal film. The kinetic of the transformation has been studied by isothermal treatment over the 390–450 °C temperature range. An activation energy of 2.2 ± 0.2 eV has been measured. Similar results have been obtained by using treatments at constant heating rate. A critical analysis of the available data suggests that the rate limiting step is the nucleation of Si grains in the aluminum film. The driving force for the process can be identified to be the free energy difference between the initial and final states.
Modelling of the Dislocation Influence on Electrical Properties of Polycrystalline Silicon Cells
Authors: Ghitani H. El , Martinuzzi S. 
Published: March 2011

ABSTRACTThe influence of the density Ndis and recombination activity Sd of dislocations on the photocurrent Jsc, the spectral variation of Jsc and electron diffusion length Ln are computed by means of the Green's function. Sd is the surface recombination velocity of the space charge cylinder surrounding a dislocation line, assumed to be perpendicular to the illuminated surface of the cells.It is found that the value and the spectral variation in the near infrared of Jsc and that of Ln, are dependent on Ndis and Sd, specially when Ndis and Sd are higher than 104 cm−2 and 104 cm s−1 respectively. A reasonnable agreement is obtained with experimental results.
Electrical Characterization of Polysilicon-to-Silicon Interfaces
Authors: Crabbé E. F. , Hoyt J. L. , Pease R. F. W. , Gibbons J. F. 
Published: March 2011

ABSTRACTThe structural properties of the polysilicon-to-silicon interface affect the electrical characteristics of devices with polysilicon contacts. The current characteristics of advanced bipolar transistors with polysilicon base and emitter contacts are very sensitive to the presence of interfacial oxides and segregated dopants. Hence, bipolar transistors provide an excellent tool for studying the effects of different interfaces on minority carrier transport. The transport of majority carriers through polysilicon-to-silicon interfaces is best investigated with contact resistance structures. In this paper, we review the correlation between interface morphology and the electrical properties of a variety of interfacial layers, ranging from native oxides to chemical oxides or thermal nitrides. Measurements on both npn transistors and contact resistance structures provide quantitative information on the trade-off between base current (i.e. current gain) and emitter resistance. Within this constraint, a variety of electrical characteristics can be obtained by tayloring the nature of the polysilicon-to-silicon interface to the device application of interest.
A Model for Dopant Pile-Up at the Interface in a Self-Aligned Polysilicon-Emitter Process
Authors: Burk Dorothea E. , Yung Shuy-Young 
Published: March 2011

ABSTRACTA model for dopant pile-up in conjunction with a self-aligned polysilicon-emitter process model is presented that accurately predicts the total dopant profiles of the polysilicon layer, the interfacial pile-up and the underlying emitter, taken from SIMS measurements. The pile-up model assumes that, after the dopant is implanted into the polysilicon layer and instantaneously redistributes there during the anneal, the dopant diffuses from its polysilicon source into the interfacial and underlying base region. In the disordered interfacial region, the dopant transport occurs by hopping, with a, certain fraction of dopant sticking in vacant sites. The model for dopant pile-up is implemented into SUPREM III. As further support, device simulations, using the respective electrically active dopant profiles, are found to be in good agreement with measurements on self-aligned phosphorus-implanted transistors.
Resistivity and Carrier Mobilities in Heavily Doped Polycrystalline Silicon Thin Films
Authors: Kim Dae M. , Qian Feng , Bickford Charles U. , Yu Simon 
Published: March 2011

ABSTRACTElectrical conduction data from heavily n and p-doped polysilicon thin films are presented. The sheet resistance in the range from 1 kΩ/□ to 100 Ω/□ is characterized over temperatures from 20°K to 450°K. It is shown that the polysilicon resistivity, larger than the corresponding crystalline value by a factor∼ 10 in the same doping range, is temperature insensitive. This larger resistivity is correlated to the degree of dopant activation and the mobility. The measured mobility varying from 8 to 20 cm 2/V.s is smaller than the corresponding crystalline value by a factor 10 ∼ 3.
Deposition and Characteristics of Polysilicon Films for Integrated-Circuit Applications
Authors: Kamins Ted 
Published: March 2011

ABSTRACTThe deposition conditions used to form polysilicon layers are determined to a large extent by the geometry of the reactor used to deposit the films. The structure of the films and the electrical behavior of devices incorporating the polysilicon layers are, in turn, influenced by the deposition conditions. Operation in the reaction-rate limited regime is necessary for film uniformity in a high-volume reactor; this is achieved by operating at low temperatures and low pressures. The temperature gradient often used in this reactor changes the structure of the deposited films, and cannot be used for devices which depend sensitively on the structure. Diffusion in polysilicon is influenced by the grain boundaries and, consequently, depends sensitively on the deposition conditions. The electrical properties of devices with their active layers within the polysilicon layer itself depend strongly on the structure of the polysilicon. Even conventional MOS transistors in which the polysilicon serves only as a conducting electrode can be affected by the structure of the polysilicon. Therefore, the deposition conditions of the polysilicon films and the resulting structure must be considered to obtain the desired electrical properties in the devices being fabricated.
Diffusion of Atoms Implanted in Poly Silicon Layer on Insulator
Authors: Takai M. , Izumi M. , Yamamoto T. , Kinomura A. , Gamo K. , Minamisono T. , Namba S. 
Published: March 2011

ABSTRACTDiffusion of arsenic implanted in poly-silicon on insulator structures after furnace and rapid thermal annealing (RTA) has been investigated by Rutherford backscattering (RBS) and Hall effect measurements. The diffusivity for As in poly–Si on insulator is represented by D = 3.12 × 104 exp (− 3.86/kT) cm/sec for the tail region after both RTA and furnace annealing and D = 34.0 exp (− 3.42/kT) cm2/sec for the peak region after RTA. Poly–Si layers after implantation and annealing were found to have tensile stresses of 3.0 – 4.0 kbar.
Phosphorus Diffusion in Polycrystalline Silicon: Monte Carlo Simulation of Experimental Diffusion Profiles
Authors: Lavine J. P. , Lee S.-T. , Black D. L. , Losee D. L. , Jarman C. M. 
Published: March 2011

ABSTRACTPhosphorus ions were implanted into silicon layers deposited by low pressure chemical vapor deposition onto thermally oxidized silicon substrates. Thermal anneals diffused the phosphorus and the resulting depth profiles were determined by secondary-ion mass spectrometry (SIMS). Transmission electron microscopy shows that the polysilicon layers have a multi-layer pattern of grains. The phosphorus profiles are fit by a Monte Carlo simulation technique that includes both grain and grain-boundary diffusion. The grain-boundary diffusion coefficient is found to be thermally activated with an activation energy of 3.3 eV.
Determination of the Nitrogen Content of as-Implanted and Annealed SIMOX Substrates
Authors: Kilner J.A. , Chater R.J. , Biswas S. , Hemment P.L.F. , Reeson K.J. 
Published: March 2011

AbstractSIMOX substrate material from two sources, both as-implanted and annealed, have been analysed by Secondary Ion Mass Spectrometry (SIMS) to determine the nitrogen concentration in the silicon overlayer. A variety of different analytical conditions were used on two different SIMS instruments to reduce the possibility of artefacts arising from the difficulties of analysing nitrogen in these materials. The nitrogen contaminant level was found to be consistently below 5 x 1017 nitrogen atoms cm-3, for all the material analysed.
Modelling of the Pattern Formation of Thin Film Silicon Single Crystals
Authors: Shangguan D.K. , Hunt J.D. 
Published: March 2011

AbstractIn this work faceted cellular growth has been investigated both experimentally and theoretically. The faceted cellular growth process and pattern formation have been modelled numerically. It is found that both the growth kinetics and the solute effect play important roles in determining the faceted cellular structure.