bluuebunny/crossref_metadata_2025_split huggingface dataset:
Positron Annihilation and Electron Spin Resonance of Electron-Irradiated 3C-SiC
Authors: Itoh Hisayoshi , Yoshikawa Masahito , Wei Long , Tanigawa Shoichiro , Nashiyama Isamu , Misawa Shunji , Okumura Hajime , Yoshida Sadafumi 
Published: September 2012

ABSTRACTPositron annihilation and electron spin resonance (ESR) have been used to study defects introduced by lMeV electron irradiation in n-type cubic silicon carbide (3C-SiC) epitaxially grown on Si by chemical vapor deposition. Positron annihilation measurements by using variable-energy positron beams indicated the narrowing of the Doppler-broadened energy spectrum of annihilation gamma-rays and the decrease in the effective diffusion length of positrons with increasing the electron fluence. These results show the formation of vacancy-type defects in 3C-SiC. An ESR spectrum labeled T1, which has an isotropie g-value of 2.0029±0.0001, was observed in electron irradiated 3C-SiC. The T1 spectrum is interpreted by hyperfine interactions of paramagnetic electrons with 13C at four carbon sites and 29Si at twelve silicon sites, leads that the Tl center results from a point defect at a silicon sublattice site. The production rate of the Tl center was in good agreement with the carrier removal rate, indicating that the Tl center captures an electron from the conduction band. All these results are accounted for by the introduction of negatively charged vacancies at silicon sublattice sites in 3C-SiC by the irradiation.
Hydrogen in Compound Semiconductors
Authors: Johnson N. M. 
Published: September 2012

ABSTRACTPhenomena associated with hydrogen in compound semiconductors include the formation of complexes with both dopant impurities and deep-level defects, the generation of hydrogen-related deep-level defects, and the migration of isolated hydrogen as a charged species. In addition to reviewing these phenomena, this paper describes the depletion-layer technique for determining thermal dissociation energies of hydrogen-impurity complexes and presents an updated tabulation of the parameters that have thus far been obtained from experimental studies to quantitatively describe hydrogen-dopant complexes and hydrogen migration in GaAs.
Characterization of Defects in CZ-grown Si Crystals with OSF Ring
Authors: Ogushi Satoshi , Hourai Masataka , Shigematsu Tatuhiko 
Published: September 2012

ABSTRACTThe nature and radial distribution of crystallographic micro-defects in CZ-grown silicon crystal wafers which exhibit OSF ring were investigated. With the difference in copper decoration XRT image and in temperature dependence of oxgen precipitation, four coaxial ring regions were clearly identified. In the OSF ring region, oxgen precipitation takes place even at relatively high temperatures around 1, 100°C. Gold diffusion experiments were also carried out, for which the ‘kick-out mechanism’ was considered to reveal the density distribution of sinks for interstitial silicon. A semi-quantitative schematic model describing the density distribution of the precipitation nuclei as a function of critical size of the nuclei for each of the four ring regions is derived. The nuclei that are stable at high temperature act as sinks for interstitial silicon atoms, generating stacking faults.
Thermal Stabilttx of Hxdrogbnation Processes into Multicrystalline Silicon
Authors: Muller Jean-Claude , Hartiti Bouchalb , Younis Hussain , Siffert Paul 
Published: September 2012

ABSTRACTWe have compared, for multicrystalline silicon solar cells, the neutralization efficiency of low energy hydrogen ion implantation to those resulting from the deposition of hydrogenated silicon nitride and determined the optimal temperature in order to have the most important improvement of the bulk diffusion length LD.In particular, the concentration profile of the introduced hydrogen has been determined by means of Elastic Recoil Detection (ERD) or nuclear reaction analysis and the electrical effects of the hydrogen investigated by the Surface PhotoVoltage (SPV) technique.At least, the stability of the LD improvement after post-thermal treatments around 400°C and at higher temperatures has been studied for two annealing modes using a classical (15 min) or a rapid lamps furnace (25 sec).
Anomalous Behavior in the Resistivity of N-I-N Polysilicon Resistors After Hydrogenation
Authors: Moore Chad B. , Ast Dieter G. 
Published: September 2012

ABSTRACTUndoped 20 μm thick polycrystalline silicon (polysilicon) films were epitaxially grown on 0.5 μm thick polysilicon seed layers prepared by cycles of CVD depositions and oxidations. The resistivity of the epitaxial films was found to vary by a factor of 4, depending on the number of deposition/oxidation cycles used to prepare the initial seed layer. Exposing the films to a hydrogen plasma for as little as 5 seconds decreased the resistivity of n-i-n resistors by four orders of magnitude and changed their activation energy from 0.4 eV to 0.001 eV. Whereas, the resistivity of p-i-p resistors only decreased by a factor of two after a 2 hour hydrogenation with no change in the activation energy. The initial high resistivity value of the n-i-n resistors was restored by either removing 0.5 μm of polysilicon from the surface of the resistors or by a 15 minute anneal in argon at 550 °C.
Mechanism of Enhanced Hydrogen Diffusion in Solar Cell Silicon
Authors: Sopori Bhushan L. 
Published: September 2012

ABSTRACTExperimental results that support our previously reported observations of enhanced diffusivity of hydrogen in some solar cell silicon are presented. The diffusivities of hydrogen, implanted at low energies, were measured for several commercial silicon substrates. It is shown that the diffusivity of hydrogen in some solar cell substrates is about two orders of magnitude higher than that in Float Zone silicon in a temperature range of 100° - 300°C. This value of diffusivity is also close to that observed along some grain boundaries in polycrystalline silicon. It is determined that hydrogen in-diffusion is accompanied by an out-diffusion of boron, and that the hydrogen diffusivity is retarded by high concentrations of oxygen. A mechanism for enhanced hydrogen diffusion is proposed which invokes formation of a highly mobile vacancy-hydrogen complex.
The Effect of Hydrogen Treatment on Electrical Properties of AIGaAsSb
Authors: Polyakov A. Y. , Stam M. , Milnes A. G. , Wilson R. G. , Bochkarev A. E. , Rai-Choudhury P. , Hillard R. J. , Pearton S. J. 
Published: September 2012

ABSTRACTThe effect of hydrogen treatment at 200°C on the concentration of electrically active defects in LPE grown AIGaAsSb is reported. In n-type layers the electrical properties are shown to be dominated by DX-like deep donors of three different types all of which are strongly passivated by the hydrogen treatment as evidenced by C-V. DLTS C-T and spreading resistance measurements. In p-type layers intrinsic acceptors of defect origin are also passivated by hydrogen. Deuterium profiles in both n- and p-type layers show characteristic plateaus indicative of formation of neutral compexes between hydrogen and dopants. Hydrogen treatment also leads to decrease of the Au/n-AIGaAsSb Schottky barrier height from 1.3 to 0.85 eV.
Plasma Hydrogenation Studies on Low-Temperature Mbe-Grown GaAs
Authors: Nakagawa O. S. , Ashok S. , Zhang K. , Miller D. L. , Chung W. K. 
Published: September 2012

ABSTRACTThe effect of hydrogen plasma on the electrical properties of low-temperature-grown GaAs (LT-GaAs) is reported. LT-GaAs epitaxial layers, 2μm thick were grown on a <100>, semi-insulating GaAs (SI GaAs) substrate using molecular beam epitaxy (MBE) at 300°C. Some of the samples were annealed in- situ at 600°C for 1 hour. These LT-GaAs samples were then subjected to hydrogen plasma at 300°C in a parallel-plate, low-frequency (30KHz) system for varying times up to a maximum of 13 hours. Current through the LT-GaAs layers as a function of voltage (I-V), temperature (I-T), and time (I-t) was measured between two surface contacts formed by thermal evaporation of Au. Evidence of partical defect passivation found in the electrical characteristics of hydrogenated LT GaAs is presented. These include reduced current at low temperature (<210K) and reduced current activation energy at high temperature (>320K).
Nuclear Magnetic Resonance Studies of Deuterium in Silicon
Authors: Bustillo Karen Carr , Haller Eugene E. , Reimer Jeffrey A. 
Published: September 2012

ABSTRACTWe report nuclear magnetic resonance measurements of deuterone diffused into silicon powders. Deuterium spectra show a two-component lineshape corresponding to two distinct hydrogen sites. The component with a narrow Lorentzian lineshape is assigned to D2 molecules. The second component is a quadrupolar doublet powder pattern, and its characteristic splitting provides a value of the electric field gradient at the site of the deuterium atom of 1.45×105 dyn/cm.
A Study of Defects in Czochralski-Grown Silicon by Positron Annihilation Spectroscopy
Authors: Sharma S. C. , Hozhabri N. , Hyer R. G. , Hossain T. , Kim S. , Meyer F. O. , Pas M. F. , Stephens A. E. 
Published: September 2012

ABSTRACTWe have studied defects in Cz-grown single crystal silicon by utilizing a variable energy positron beam and positron lifetime spectroscopy in conjunction with surface photovoltage measurements. We present results for the depth profile of defects obtained from the Doppler broadening spectra measured by implanting variable energy positrons at different depths ranging from the surface down to ∼ 1 /xm deep. We have also measured positron lifetime spectra at different locations on a wafer and have obtained a radial variation in the density of the vacancy-type defects.
The Electronic States and Dynamical Properties of Hydrogen Bound to Carbon in Silicon
Authors: Kamiura Yoichi , Hashimoto Fumio , Yoneta Minoru 
Published: September 2012

ABSTRACTThis paper demonstrates a unique action of hydrogen on defects and impurities in semiconductors. Hydrogen injected into n-type Si by chemical etching or hydrogen plasma not only pas-sivatcs phosphorus but also electrically activates carbon by forming a H-C complex acting as an electron trap E3 (0.15). A model of the structure and electronic state of the H-C complex is proposed on the basis of available experimental data on the properties of the complex. The diffusion coefficient of isolated hydrogen below 300K is evaluated from its diffusion process to phosphorus after the photoinduccd dissociation of the H-C complex. Some differences in hydrogen diffusion between chemically etched and plasma hydrogenated crystals arc discussed.
Diffusion of Hydrogen and Hydrogen-Dopant Interactions in Si Doped GaAs and GaAlAS Alloys
Authors: Chevallier J. , Machayekhi B. , Grattepain C. , Rahbi R. , Theys B. 
Published: September 2012

ABSTRACTDeactivation of silicon dopants by hydrogen in GaAs and GaAlAs proceeds through the formation of hydrogen-dopant complexes with thermodynamical and vibrational characteristics weakly sensitive to the alloy composition. However the hydrogen diffusion profile is strongly sensitive to the alloy composition. In GaAs:Si, the profile is an erfc function while in Ga1-xAlxAs:Si with x > xo, it is rather a step like function. From the doping level dependence of xo, we explain the hydrogen diffusion properties within a model where H° and H-govern the diffusion profiles respectively for x < xoand x > xo. We deduce that hydrogen behaves as a deep acceptor in these materials with a level slightly resonant in the conduction band of GaAs and localized in the band gap of Ga1-xAlxAs alloys for x > 0.07.
Optical Emission Study of the Energy Levels of Ga-VACANCY/HYDROGEN Complexes in N and P-TYPE GaAs
Authors: Amore Bonapasta A. , Bonanni B. , Capizzi M. , Cherubini L. , Emiliani V. , Frova A. , Sarto F. 
Published: September 2012

ABSTRACTThe formation of Ga-vacancy/hydrogen complexes in GaAs has been detected via photoluminescence measurements. Different degrees of hydrogénation can be achieved by low-energy H- or D-ion irradiation from a Kaufman source. The volume incorporation, for equal treatment, is dependent upon the density of impurities and defects where H can bind. In originally p-type MBE-GaAs, prolonged hydrogen treatments lead to the appearance of three emission structures in the range 1.15–1.34 eV. The results are explained in terms of transitions to different states of charge of gallium vacancies trapping one or more H-atoms, the activity of the individual states being dependent upon the H-dose and the nature of the laser excitation. The model is supported by comparison with the changes in the Ga-vacancy/donor emission band in degenerate n-type samples, as it evolves, from the virgin condition, through hydrogenation. The present observation provides also valid support to the creation, in p-type material, of a semi-shallow donor associated to H trapped along the As-Ga bond, in the immediate neighborhood of the gallium vacancy.
External Gettering and Hydrogenation Effects on Electrical Properties of Multicrystalline Silicon Wafers
Authors: Perichaud I. , Martinuzzi S. 
Published: September 2012

ABSTRACTTo reduce the density of recombination centers, external gettering by phosphorus diffusion from a POCI3 source and hydrogénation were applied to 200 μm thick samples.Gettering was carried out at 850°C or 900°C, for 120 or 240 mn. Hydrogénations result of the annealing of samples at 400°C for 30 mn in gas flow. Thanks to arrays of mesa diodes, it is found that minority carrier diffusion lengths (Ln) are neatly improved by the gettering. The improvements are higher at 900°C than at 850°C, they increase with gettering time and SIMS analyses indicate that they are due to the removing of Fe, Cu and Ni atoms.Hydrogénation enhances Ln values in samples gettered at 850°C and the higher Ln the longer the gettering time. After hydrogénation, the values of Ln in the samples gettered at 850°C are comparable to those measured in samples gettered at 900°C. It is assumed that hydrogen is able to neutralize the activity of impurities which have not been gettered, like oxygen, and also that of residual metallic impurities.
Electrical and Optical Properties of Titanium, Vanadium, Molybdenum, and Tungsten Related Defects in Silicon
Authors: Schmalz K. , Grimmeiss H. G. , Pettersspn H. , Tilly L. 
Published: September 2012

ABSTRACTRecent studies of the deep transition-metal centers Ti, V, Mo and W in silicon are discussed, which have been investigated using junction-space charge techniques. The changes in the Gibbs free energy, enthalpy, and entropy due to electron or hole excitation of these transition metal related levels are presented. The good agreement of the Gibbs free energies with the optical threshold energies of the corresponding photoionization cross sections suggests negligible lattice relaxation. For the Ti-doped samples three energy levels at Ec-0.065 eV, Ec-0.295 eV and Ev+0.255 eV at 80 k were observed. For Mo and W the energy levels are located at Ev+0.298 eV and Ev+0.379 eV, respectively, at 80 K. Three energy levels of the V-related centers exist at Ec-0.207 eV, Ec-0.483 eV and Ev+0.356 eV at 0 K. A structure in the low-energy part of the spectral distribution of the level Ec-0.483 eV is assumed to be due to excited states and shown to be in good agreement with effective-mass theory. Previous assignments of the energy levels should be reconsidered.
Transformation of Gold in N-Type Silicon from a New Deep Level to the Gold Acceptor Level
Authors: SveinbjöRnsson Einar Ö. , Engström Olof 
Published: September 2012

ABSTRACTUsing deep level transient spectroscopy (DLTS) on gold-doped n-type Czochralski (CZ) and float zone (FZ) silicon we observe a new gold-related acceptor level (G) with an activation energy σn= 0.19 eV and an electron capture cross section On = 1–10-17 cm2. The center anneals out at a temperature of 250°C, simultaneously as the gold acceptor concentration increases. Annealing at temperatures below 250°C does not reverse this process. However, etching a few microns off the sample surface using HF:HNO3 based etch reforms the G center and the gold acceptor concentration decreases accordingly. From DLTS depth-profiling we determine that the new center is only found at depths less than 5 μm, and in the same region we observe neutralization of phosphorus dopants and a reduction in the gold acceptor concentration.We propose that in-diffusion of hydrogen during the etching process is responsible for the three observed transitions, i.e. neutralization of both phosphorus donors and gold acceptors and formation of the G center. We suggest that there are (at least) two possible Au-H complex centers, one which is electrically inactive and another which gives rise to an acceptor level (ΔE = 0.19 eV) in the bandgap of n-type silicon. The electrically active center anneals out at 250°C while the electrically inactive one is more stable and has been observed earlier in remote plasma hydrogenation experiments performed at 150–350°C.
Proof of the Acceptor State of the Trigonal Iron-Boron Pair in Silicon by Electron Paramagnetic Resonance Measurements
Authors: Gehlhoff W. , Rehse U. 
Published: September 2012

ABSTRACTFor the first time the acceptor state of iron-boron pairs the occurence of which are suggested by electrical measurements and theoretical considerations is directly proved by EPR measurements. The corresponding EPR spectrum is observed upon suitable illumination of samples which have been co-doped with boron and iron. It shows trigonal symmetry, and the fine-structure pattern can be described with the spin S = l, the g-values gi ∼ 2.1345±0.0001, gi = 2.1345±0.0004 and the zero-field splitting parameter |D| = (1.418±0.001) cm−1.
Excitonic Mechanism of Rare Earth Excitation in II-VI and IH-V Semiconductors
Authors: Godlewski Marek 
Published: September 2012

ABSTRACTIn this paper we analyze processes which may improve the efficiency of low- and high- field electroluminescence devices based on rare earth doped II-VI and III-V semiconductors. The main topicsare the processes which follow impact ionization, i.e., carrier trapping and/or exciton binding. Excitonic excitation mechanism is shown to occur also for ions which are not directly ionized, as observed recently for some rare earth impurities in II-VI and III-V semiconductors.
Donor-Acceptor Pairs in Silicon
Authors: Altink H. E. , Gregorkiewicz T. , Ammerlaan C. A. J. 
Published: September 2012

ABSTRACTStable forms of donor-acceptor pairs in silicon arise from the interaction between negatively charged acceptors and 3d transition element donors, which, occupying interstitial sites, have high mobilities. The atomic and electronic structure of these pairs can be studied in detail by magnetic resonance. The symmetry of centers as observed in the resonance experiments gives strict constraints on the applicable atomic models. The spin of centers is related to their charge state. Hyperfine interactions frequently lead to a specific structure in the spectra, which characterizes the chemical identity of atomic components of the pair. Deep level transient spectroscopy provides a way of sensitive observation of electrically active impurities: to determine their concentrations and associated electronic levels. It allows the study of the kinetics of the pair formation process and thermally induced dissociation; binding energies can be determined. Transformation of pairs as a result of illumination was also observed. Several of the pairs can exist in geometrically different atomic configurations leading to the phenomenon of bi- or multi-stability. In the paper the donor-acceptor pair formation process is illustrated by examples involving the substitutional double acceptor zinc, for which new data became recently available.
Metastable Defects of Iron-Boron Pair in Silicon
Authors: Nakashima H. , Sadoh T. 
Published: September 2012

ABSTRACTWe have found configuratlonally metastable Fe-B pairs in Si by using dark or photo capacitance-transient technique combined with minority-carrier injection. The metastable pairs are observed as four electron-trapping levels at Ec-0.43 eV, 0.46 eV, 0.52 eV, and 0.54 eV and as two hole-trapping levels at Ev+0.53 eV and 0.48 eV after the injection at 150 K. The production of each level is investigated under various injection conditions, and the annihilation process is studied by isochronal anneals.
Origins of the Gap States in Polycrystalline Silicon: Tight-Binding Calculations of Twist Boundaries
Authors: Kohyama M. , Kose S. , Yamamoto R. 
Published: September 2012

ABSTRACTThe atomic and electronic structures of the twist boundaries Σ (=3 (011), Σ=7 (111) and Σ=5 (001)) in Si have been calculated by using the transferable SETB method coupled with the supercell technique. The twist boundaries in Si contain larger structural disorder or more defects and larger interfacial energies than tilt grain boundaries. Several kinds of structural disorder or defects have been found to generate characteristic electronic states inside the gap. The present structural disorder or defects and the gap states are the candidates of the origins of the observed band-tails or mid-gap states in polycrystalline Si as well as those In amorphous Si.
Effects of Hydrogen or Nitrogen on Growth of Oxygen-Related Defects in Germanium
Authors: Makihara Noboru , Ito Kazuyoshi , Mizuno Kaoru , Ono Kotaro 
Published: September 2012

ABSTRACTOxygen-doped germanium crystals were used to demonstrate the interaction between implanted hydrogen or nitrogen atoms and the oxygen-related defects. The electron trap at Eo-0.26eV associated with the germanium A-center was found to be formed by electron irradiation. Another level at Eo-0.21eV also was observed on annealing at 120 °C. As for the sample implanted with hydrogen ions following electron irradiation, the trap concentration is four times as large as that for electron irradiation alone. It is probable that the germanium A-centers produced by electron irradiation capture hydrogen atoms and increase electrically active centers. After nitrogen implantation following electron irradiation, the Eo-0.26eV level almost annealed out at 140 °C and the trap at Eo-0.21eV wasn't observed. We propose that the reduction in the oxygen-related defect growth is due to the prevention of defect migration with nitrogen atoms.
Similarity of Vacancy Creation Mechanisms in Si Doped GaAs and Ga Doped ZnSe Observed by a Monoenergetic Positron Beam
Authors: Tanigawa S. , Lee J. L. , Wei L. , Kawabe M. , Miyahma T. , Okuyama H. , Akimoto K. , Mort Y. 
Published: September 2012

ABSTRACTThe impurity effects on the creation of vacancies in GaAs and in ZnSe were investigated by monoenergetic positron beam measurements. In the case of the Si-doped MBE grown GaAs, the doping of Si atoms was found to enhance the creation of Ga site vacancies. The concentration of Ga vacancies was found to be proportional to the doped Si concentration. The observed linear relation between both concentrations supports the theoretical prediction on the creation of Ga vacancies in terms of the change in the Fermi-level position by the Si doping into GaAs and also suggests that Si atoms diffuse in GaAs as a neutral complex of Ga vacancy-Si pair rather than that of Si-Si pair. In the case of the Ga-doped MBE grown ZnSe, Zn vacancies were found to be generated in proportion to the concentration of doped Ga atoms. The observed similarity of the vacancy creation in the Si-doped GaAs and in the Ga-doped ZnSe can be well explained by the consideration of the charge neutrality condition around impurities.