bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Formation of Amorphous Silicon by Light Ion Damage
Authors: Shih Y. , Washburn J. , Weber E.R. , Gronsky R. 
Published: March 2011

ABSTRACTA model for formation of amorphous silicon by light ion implantation is proposed. It is suggested that accumulation of point defects and/or complexes is required at the initial stage of the amorphization process. Amorphous zones can only form at the end of incoming light ion tracks when the pre-accumulated concentration of point defects reaches a critical value. Depending on the uniformity of the point defect distribution, two possibilities for the second stage of amorphization are suggested when ion implantation is performed at different temperatures.Silicon wafers implanted with boron ions below and above the critical amorphization dose at various temperatures have been investigated using cross section specimens in high resolution TEM. Complementary analyses of these specimens by Electron Paramagnetic Resonance have revealed the presence of dangling bonds in amorphous zones and point defect clusters. Extrinsic stacking faults with 1/3 <111> displacements and other smaller distortions with 1/x<111> displacements were also found to result from the amorphization process. Liquid nitrogen temperature was found to be necessary to cause complete amorphization of silicon by boron ion implantation.
Rapid Thermal Processing (RTP) of Shallow Silicon Junctions
Authors: Seidel T.E. 
Published: March 2011

ABSTRACTRapid Thermal Processing (RTP) is used to study shallow junction formation for high dose implanted silicon. The residual damage from As damage is efficiently removed using high temperature-short time anneals (1100°C - few seconds), while limited arsenic atom diffusion is obtained. The diffusion properties are also characterized by concentration enhanced diffusion at higher doping. The higher doping is metastable, with reversible changes in resistivity observed for sequential 1100°C-800°C-1100°C-800°C thermal cycles. RTP gives shallower defect free As junctions than standard long time anneals. Boron junctions are limited by the depth extension of a large ion-channeling-tail which is shown to undergo local enhanced diffusion. The approaches to form shallow p+ junctions without channel tails are discussed. A summary of ion damage studies is made. Some generalizations for determining an RTP advantage or disadvantage are made, based on activation energy differences of effects.
Electronic Stopping Power for Low Energy Ions
Authors: Azziz N. , Brannon K. W. , Srinivasan G. R. 
Published: March 2011

ABSTRACTA procedure to be used in ion implantation calculations has been developed to determine the stopping power of an ion at low energy as a function of its effective charge. The ion effective charge accounts for screening of the ion and has been found to have considerable effect on the stopping power through its dependence on the target electron density. Steps in the procedure include: the calculation of the Fermi momentum of the target, calculation of the relative velocity between the projectile and target electron cloud, determination of the screening distance for the ion, and calculation of the proton stopping power Sp according to the density-functional formalism. The ion stopping power is then is the ion effective charge. The procedure can be applied to semiconductors and metals. Comparisons are reported with the predictions of the Firsov and Lindhard methods which do not include any effective charge or shell structure considerations. The computer program MARLOWE has been modified to include this method for calculating the stopping power. Results in the form of implanted boron profiles in silicon will be presented.
The Entropy of Defects and Diffusion in Silicon
Authors: Bar-Yam Y. , Joannopoulos J. D. 
Published: March 2011

AbstractTheoretical calculations of the finite temperature properties of defects, such as defect concentration and diffusion rate, require a knowledge of the entire 3N-dimensional defect total energy surface. We present a formalism for obtaining such defect energy surfaces from total energy calculations. Preliminary results of the application of this formalism to the silicon selfinterstitial are described. Implications for understanding the remarkable experimental high temperature diffusion entropies are discussed.
Electronic Structure of Mercury, Gold and Platinum Impurities in Silicon
Authors: Leite Jose R. , Alves Jose L.A. 
Published: March 2011

AbstractThe electronic structures of substitutional and tetrahedral-site interstitial Hg+, Auo and Pt− isoelectronic impurities in silicon have been analysed. The centers are theoretically described by the Watson-sphereterminated molecular cluster model within the framework of the multiplescattering Xa formalism. At the substitutional sites the centers are related to the “vacancy” model recently proposed to describe the properties of the elements at the end of the transition-metal series. At the interstitialsites the impurities introduce a hyperdeep s-like level close to the bottom of the valence band and, in agreement with experiments, do not show shallow donor activities. For all the analysed centers the d-states remain fully occupied below, or within, the valence band.
Photo-EPR and Spatially Resolved EPR of ASGa in As-Grown GaAs
Authors: Baeumler M. , Kaufmann U. , Windscheif J. 
Published: March 2011

AbstractThe photo-response of the ASGa+ antisite electron-paramagnetic-resonance (EPR) has been studied in as-grown GaAs as a function of illumination time and photon energy. The results establish a firm and positive correlation between ASGa and the deep donor level EL2. Spatially resolved EPR measurements show that the ASGa concentration can fluctuate by about a factor of two across a 2-inch semiinsulating GaAs wafer.
High Resolution Optical Study of The Antisite Defect ASGa in GaAs; Correlation with Midgap Level EL2
Authors: Skowronski M. , Lin D.G. , Lagowski J. , Pawlowicz L.M. , Ko K.Y. , Gatos H.C. 
Published: March 2011

AbstractA high resolution optical study was carried out on GaAs crystals containing only the EL2 midgap level. The no-phonon line at 1.039 eV was identified as an intracenter transition within AsGa. An excellent correlation was found between the intensity of the no-phot1n AsGa line and the characteristic EL2 absorption. A correlation was also found between the characteristic optical absorption of EL2 and its concentration as determined by DLTS measurements. These results prove the direct association of EL2 with a neutral state of AsGa The presence of another midgap level ELO, contained in heavily doped oxygen crystals had no effect on the optical spectra of EL2, but it did alter the DLTS measurements. Thus, an accurate calibration was obtained for the determination of EL2 by optical absorption based on DLTS measurements on crystals containing only EL2 and thus involving no uncertainties introduced by other midgap levels.
Spatial Distribution of Neutral EL2 as Measured Optically for Thin Semi-Insulating GaAs Wafers, and Relevance to Device Parameters
Authors: Dobrilla P. , Blakemore J. S. , Gleason K. R. , McCamant A. J. 
Published: March 2011

AbstractMeasurements are reported, for 0.5 mm thick semi-insulating (S.I.) GaAs wafers, of the neutral EL2 distribution, the pattern of dislocations, and of MESFET electrical parameters - these devices built on the same wafers. These results indicate that the device properties are more affected by EL2 nonuniformity than by dislocation density pattern.
Defect Identification in Silicon Using Electron Nuclear Double Resonance
Authors: Ammerlaan C.A.J. , Sprenger M. , Kemp R. Van , Wezep D.A. Van 
Published: March 2011

AbstractThe application of electron nuclear double resonance (ENDOR) for identification and characterization of point defects in silicon is reviewed. Taking the vacancy and the boron-vacancy complex as examples it is discussed how ENDOR can provide information on the atomic and electronic structure of paramagnetic centers.
Endor-Investigation OF Al ++ AND Al ++-Al- PAIRS IN SILICON
Authors: Niklas J.R. , Spaeth J.-M. , Watkins G.D. 
Published: March 2011

AbstractWith Electron Nuclear Double Resonance (ENDOR) ligand superhyperfine (shf) interactions were investigated for 7 neighbor shells of the interstitial Al ++ center (Si-G18) and for 10 neighbor shells of the Al ++-Al-pair center (Si-G19). All shells of the interstitial center exhibit undistorted Td symmetry confirming the defect model derived from earlier experiments. In the pair center the shf interaction of the Al++ with the neighboring Al nucleus shows a pure [111]-symmetry, also the shf interactions with the outer Si-neighbor shells exactly reflect this axial [111]-symmetry of the defect. The magnitude of the quadrupole interaction of the neighboring Al nucleus clearly shows, that this nucleus is a nearest neighbor of the Al++. From the angular dependence and the intensity ratios of ENDOR lines of the pair center it can be excluded that any additional impurity is associated with the Al++-Al- pair at least within the first 3 neighbor shells of the AI++. The influence of the Al- neighbor on the hyperfine axes of the first [111] Si-neighbors is negligible and is also remarkably small for the other Si-neighbors. The magnitudes of the ligand shf interactions for the pair center are closely related to those of the Al++ center. A comparison of these values for both centers allows a definite assignment of the measured shf interactions to their corresponding neighbor shells for the Al++ center.
The Effect Of Uniaxial Stress on the Infrared Absorption Bands Due to the Oxygen Donor in Silicon
Authors: Stavola M. , Lee K. M. , Nabity J. C. , Freeland P. E. , Kimerling L. C. 
Published: March 2011

ABSTRACT:We have investigated the effect of stress upon the infrared absorption spectrum of the neutral charge state of the oxygen donor in silicon. Our results show that the central cell of the donor has C2ν, symmetry and that this anisotropy gives rise to a ground state wave function that is constructed from a single pair of conduction band valleys.
Thermal Donor Removal by Rapid Thermal Annealing: Infrared Absorption
Authors: Stein Herman J. , Hahn S. K. , Shatas S. C. 
Published: March 2011

AbstractRapid thermal annealing of thermal donors in Si with 10 sec anneal times at temperatures between 600 and 1000 °C has been investigated by infrared absorption at 80 K. Thermal donors A through D, which are identified by excited state absorption, are present in as-grown Czochralski Si; whereas excited states for donors A through F as well as photoionization of thermal donors are observed after extended heating at 450 °C. The temperature required for rapid thermal annealing is lower when only donors A through D are present. Removal of thermal donors A through F by rapid thermal annealing at temperatures > 800°C restores 7 to 8 oxygen atoms to interstitial sites per electricallӯ measured donor removed. This ratio supports oxygen cluster models for thermal donors but does not support previous suggestions that such clusters are embryonic forms of high temperature oxygen precipitates.
Identification of Impurities and Defects in Semiconductors by Optical Spectroscopy
Authors: Skolnick M. S. 
Published: March 2011

AbstractA review is given of the information that can be obtained on defect centers in semiconductors by optical spectroscopy. Particular emphasis is given to donor and acceptor identification, and symmetry determination of transition metal and axial defect-complex centers. The information that can be obtained from isotope doping effects is discussed.
Infrared Mapping of Oxygen and Correlation with Electrical Measurements on CZ Grown Wafers
Authors: Whitfield J. , Boyle R. 
Published: March 2011

AbstractSpatial variation of interstitial oxygen concentrations ([Oi]) have been observed in wafers sliced from CZ grown ingots. Oxygen precipitation can occur with subsequent heat treatments causing non-uniform electrical device characteristics across a processed wafer. A new method is presented using infrared absorption measurements to map [Oi]in silicon wafers for correlation with wafer electrical measurements. The new infrared mapping method uses a spectrometer fitted with a software controllable wafer positioner. 100 m m diameter wafers were mapped to show the concentration variations and oxygen precipitation effects resulting from thermal heat treatments. Electrical measurements were made on nearly adjacent wafers from the same ingot and subjected to the same thermal cycling plus a diode-capacitor fabrication process. Two types of electrical measurements were used to map diode-capacitor arrays: reverse leakage current (Ir) and transient reverse recovery lifetime (τr. The measured values for each device tested were positionally correlated to the fourier transform infrared spectrometer (FT-IR) [Oi] data. Scatter plots were generated by plotting the electrical measurements as a function of the interpolated concentration data or differential concentration data parameterized at equivalent positions on the wafers. The scatter plots show that the electrical characteristics are strongly dependent on the precipitated oxygen (∆ [Oi]) for larger values of ∆[Oi], but nearly independent for lower ∆[Oi] values.
Oxygen-Nitrogen Interactions in Ion-Implanted Silicon
Authors: Stein H. J. 
Published: March 2011

AbstractInteraction of oxygen and nitrogen in ion-implanted crystalline silicon layers has been investigated by infrared absorption. Infrared absorption bands which are not produced by either 14N or 160 alone are observed after sequential implantation of 14N and 160 into overlapping profiles followed by annealing at 500°C. The new bands indicate oxygen - nitrogen interactions and are ascribed to Si-N vibrational modes with oxygen in nearby interstitial sites.
Defect States in GaAs after Rapid Thermal Annealing
Authors: Street R. A. , Johnson N. M. , Burnham R. D. 
Published: March 2011

AbstractElectronic deep levels in GaAs have been investigated by correlated luminescence and DLTS measurements on material in which the defects were systematically perturbed by rapid thermal annealing. The samples were grown by MOCVD and encapsulated with silicon nitride. Annealing was performed at temperatures from 800°C to 950°C for 5 seconds. The luminescence spectra were measured from 0.7 to 1.6 eV at temperatures from 4-80 K and have features at 0.97, 1.17, 1.35, 1.40 and 1.5 eV. The band-to-acceptor luminescence shows the formation of Si acceptors, starting at an anneal temperature of about 850°C. The luminescence peak at 1,35 eV, attributed to As vacancy - acceptor complexes, is observed to increase in intensity with higher annealing temperatures. In contrast, the Ga vacancy-donor complex peak at 1,17 eV decreases in intensity. DLTS data show an increase in the density of deep levels and new levels not present in the unannealed material. Capacitance-voltage data find a reduction in carrier concentration, although type conversion is not observed even after annealing to 950°C.
The Donor State of Vanadium in Indium Phosphide
Authors: Bremond Georges , Nouailhat A. , Guillot G. , Deveaud B. , Lambert B. , Toudic Y. , Clerjaud B. , Naud C. 
Published: March 2011

AbstractWe have performed studies on Vanadium doped InP, especially p-type InP codoped with Zn and V. Luminescence excitation experiments, DLTS, DLOS and absorption experiments lead to the conclusion that the donor level (V3+/V4+) of Vanadium is at about 0.2 eV above the valence band. Optical cross-sections that are determined by DLOS allow to observe for the first time a resonance in the valence band of a III-V semiconductor that we tentatively interpret as an excited state of V4+.
Defects in GaAs as Revealed by Chemical Etching
Authors: Lessoff H. , Tseng W. 
Published: March 2011

AbstractA new eutectic etchant for GaAs has been developed to display (a) the normal etch pit patterns, but also to reveal (b) rectangular, (c) shallow matrix and (d) raised geometric patterns. Results on various GaAs substrates, ranged from undoped to In-, Cr-, Te-, Si-doped materials, show a general trend: The materials having the numbers of (a), (b) and (c) etched patterns are roughly in the above order (from high density to low density). Whereas, for the density of the raised geometric patterns, the ranking is reversed. It is concluded that the major factor in developing the (a), (b) and (c) etched patterns is due to the stress, while the (d) pattern may be due to dopant and its influence on Ga to As bondings.
Charge Trapping by Deep Donors in Si-Doped AlxGa1-xAS
Authors: Mooney P. M. , Caswell N. S. , Solomon P. M. , Wright S. L. 
Published: March 2011

AbstractThe kinetics of charge capture by deep donors in AlxGa1-xAs have been measured. The time dependence indicates that a single energy cannot be used to describe the trap. A model assuming thermally activated capture into a resonance in the conduction band with a range of energies gives excellent fits to the data and provides a measure of the energy range for the trap. This model is consistent with the large lattice relaxation model for DX centers. The increase of the activation energy for capture as the Al mole fraction is decreased contradicts the model which attributes the decay of the persistent photoconductivity to tunneling through the heterojunction barrier in modulationdoped structures.
The Effect of Hydrostatic Pressure on Defect Annealing in Semiconductors
Authors: Barnes C.E. , Samara G.A. 
Published: March 2011

AbstractWe report the first study of the effect of hydrostatic pressure on the annealing of defects in Si and GaAs. It is shown that the application of hydrostatic pressure enhances the annealing rate in these materials. Analysis of the data yields the lattice volume relaxation accompanying annealing.
Acceptor and Donor Impurities in Semiconductors Studied by the PAC—Method
Authors: Forkel Doris , Futtinger H. , Iwatschenko-Borho M. , Meyer F. , Witthuhn W. , Wolf H. 
Published: March 2011

AbstractThe perturbed angular correlation method (PAC) is applied to semiconductors. This technique is based on the detection of the electric quadrupole hyperfine interaction by means of radioactive nuclei. The highly localized sensitivity of the PAC-method favours the investigation of localized distortions of the lattice due to impurities as donor or acceptor atoms.Results are given for radioactive 111Cd atoms in the semiconductors In2 Te5, ZnO, and Si. The observed electric field gradients (EFG) and their orientations with respect to the crystal axes yield information on the local structure around the probe atoms. In Na—or Li—doped ZnO the formed Na—O—In (or Li—O—In) complexes show identical axial symmetric EFG tensors. In the case of In2Te5 acceptor level energies could be deduced from the temperature dependence of the EFG.
Dislocation Trapping Potential Measured by SEM-CCM
Authors: Mil'Shtein Sam 
Published: March 2011

AbstractThe intensity of contrast and width of the image of a single dislocation in silicon were measured versus bias of Schottky barrier at room temperature. A regime of measurements was established, which reduced dramatically the number of variable parameters involved in contrast formation. In addition, using the right regime of SEM-CCM one can determine the position of a defect relative to the surface of the specimen without doing TEM measurements. It was shown for the first time that from contrast readout one can determine the dislocation electrical potential. A model of image formation is discussed.
Electronic Ground State of Iron-Acceptor Pairs in Silicon
Authors: Ammerlaan C.A.J. , Kooten J.J. Van 
Published: March 2011

AbstractIron-acceptor impurity pairs, consisting of a positively charged iron ion trapped on an interstitial site in the vicinity of an ionized acceptor, in silicon were observed by electron paramagnetic resonance for all common acceptor dopants (B, Al, Ga, In). The Zeeman splittings of these pairs, to which both spin and orbital momenta contribute, cover the range between 1.1 and 6.4. An interpretation of these spectroscopic splitting factors is presented, which considers the effects of the crystal field - of cubic, axial, or lower symmetry - and of spin-orbit interaction on the 4F ground state of the iron ion in a (3d)7 configuration. It is concluded that the apparent quenching of the orbital angular momentum is not due to a dynamical Jahn-Teller effect, nor due to hybridization. Rather, it is proposed that a significant reduction, by about 80%, of the orbital magnetism arises from covalency.
Ebic Analysis of Hydrogen Passivation of Defects in Silicon
Authors: Hanoka J.I. , Dube C.E. , Sandstrom D.B. 
Published: March 2011

AbstractEBIC evidence of the key role of dislocations in hydrogen passivation of EFG ribbon is presented. Dislocations, and not bulk point defects, are shown to be both the principal defect being passivated and the means whereby rapid thermal diffusion of hydrogen takes place. Passivation of dislocation arrays to depths of the order of hundreds of microns has been observed. Low stemperature EBIC (96°K < T < 300°K) has shown that shallow electron traps associated with dislocations and within ∼0.1 eV of the conduction band are not passivated while (proposed) deeper mid-gap levels at the same spatial location are readily passivated. A general dislocation model for hydrogen passivation applicable to all polycrystalline silicon is presented.
Direct Measurement of the Subsurface Hydrogen Barrier Layer in Plasma-Treated Silicon Ribbon
Authors: Jaworowski A.E. , Wielunski L.S. , Listerman T.W. 
Published: March 2011

AbstractThe near-surface hydrogen profile was measured using the 15N hydrogen profiling technique in silicon ribbon grown by the edge-defined film-fed growth (EFG) process. This direct method has a high depth resolution of 10 - 30 Å, can be used to a depth of several microns, and can measure hydrogen in concentration of 100 at. ppm. By appropriate surface treatment we were able to observe for the first time the separation of the near-surface hydrogen profile in silicon from the surface hydrogen contamination layer. Using our technique, hydrogen profiling of the near-surface region revealed the existence of a subsurface hydrogen layer which acts as a barrier to the transfer of hydrogen into the bulk of both passivated and untreated silicon. The structure of this hydrogen barrier was measured for different plasma treatments.
Exponential Band Tails at Silicon Grain Boundaries
Authors: Werner J. , Peisl M. 
Published: March 2011

AbstractThe energy-distribution of interface states at grain boundaries in fine-grained silicon films is measured by two independent methods. The analysis reveals deep exponential band tails in the two-dimensional density of states within the band gap. It is proposed that these tails originate from Anderson localization of free carriers within potential fluctuations along the grain boundary plane. The measurements are in good agreement with this model.
Photoluminescence and Raman Spectroscopy of Cubic SiC Grown by Chemical Vapor Deposition on Si Substrates
Authors: Freitas J.A. , Bishop S.G. , Addamiano A. , Klein P.H. , Kin H.J. , Davis R. 
Published: March 2011

AbstractThin films of cubic SiC were grown on Si substrates by a new CVD heteroepitaxial technique. The cubic polytype and crystal quality were verified by room temperature Raman spectroscopy. Low temperature photoluminescence (PL) studies detected nitrogen donor bound excitons, N-Al donor-acceptor pairs in Al-doped samples, and some defect complexes usually observed only in irradiated samples. Evidence of strain due to the Si-SiC lattice mismatch was observed in both the Raman and PL spectra and the effects of substrate removal and high temperature annealing on these optical spectra were studied.