bluuebunny/crossref_metadata_2025_split huggingface dataset:
ODMR of Shallow Donors in Zn-Doped Lec-Grown InP
Authors: Trombetta J. M. , Kennedy T. A. 
Published: March 2011

AbstractODMR spectra observed while monitoring the shallow donor-shallow acceptor pair emission in Zn-doped LEC-grown InP display strong features in the region near the conduction electron value of g=1.20. In addition to a previously observed narrow line, we observe a much broader resonance which dominates at low photoexcitation intensity. This broader line is interpreted as the unresolved exchange split resonances of electrons bound to residual shallow donors. The exchange broadening arises from interactions with nearby paramagnetic centers. Both resonances result in a decrease in the shallow-donor-to-shallow-acceptor radiative recombination and give evidence for pair recombination processes which compete with this emission.
Defect Induced Luminescence from MBE Prepared Si/Si1-xGex Superlattices
Authors: Northrop G.A. , Iyer S.S. , Wolford D.J. 
Published: March 2011

AbstractWe report the first definitive observation of photoluminescence from Si/Si1-xGex superlattice heterostructures. Excitons bound to a deep-level radiation damage center (I1) are observed in a series of low Ge content (x = 0.05) unrelaxed structures. We also present preliminary results on photoluminescence from as-grown narrow period (Si6Ge4) superlattices.
Fermi Resonance Effects on the Vibration Modes of Hydrogen-Passivated Boron in Silicon
Authors: Watkins G.D. , Fowler W.B. , Deleo G.G. , Stavola M. , Kozuch D.M. , Pearton S.J. , Lopata J. 
Published: March 2011

Abstract10B - 11B isotope shifts have been reported recently for the vibrational frequencies of hydrogen (H) and its isotope deuterium (D) in the H-B complex in silicon. The D-10 B - D11 B shift was found to be anomalously large. We show that this effect finds a natural explanation in a phenomenon called “Fermi resonance”, arising from a weak anharmonic coupling between the second harmonic of the transverse B vibration and the longitudinal D vibration. We first present a simple classical explanation of the effect in terms of a “parametric oscillator”, or a child pumping a swing. We then outline a simple quantum mechanical treatment that provides a satisfactory quantitative explanation of the results. Our calculations also predict infrared absorption at the boron second harmonic frequencies. These are observed for both 10B and 11B with intensities and polarization as predicted, providing direct confirmation of the interpretation. The Pankove Si-H-B model, therefore, remains intact.
Hydrogen Diffusion in Boron-Doped Silicon
Authors: Herrero C.P. , Stutzmann M. , Breitschwerdt A. 
Published: March 2011

AbstractInfrared reflectance spectroscopy is employed to obtain hydrogen depth profiles in boron-doped silicon, hydrogenated under various plasma conditions. From the obtained profiles, H-diffusion coefficients are calculated for different temperatures and dopant concentrations. Our results are interpreted by assuming that diffusion in the bulk is limited by trapping at the acceptor sites. A binding energy of 0.6 eV is deduced for B-H pairs. We also analyze the influence of a bias applied to the sample on the hydrogenation process. This sample bias can favor or completely hinder the diffusion of hydrogen into the silicon bulk. Also, a surface oxide layer can drastically inhibit the hydrogen in-diffusion.
Structure and Metastabiltty of Muonium Centers in Semiconductors and their Simulation of Isolated Hydrogen Centers
Authors: Estle T.L. , Kiefl R.F. , Schneider J.W. , Schwab C. 
Published: March 2011

AbstractThe study of isolated hydrogen in semiconductors is difficult because of the tendency for hydrogen to form complexes. An alternative to direct studies of hydrogen is the study of tnuonium in semiconductors. In such experiments the muon is essentially an isotope of hydrogen with th the mass of the proton. Twenty isolated muonium centers have been observed in tetrahedrally-coordinated crystals ranging from Si to the cuprous halides. Muon level-crossing resonance has provided detailed information on neutral interstitial muonium located at a bond center in Si (the analog of the hydrogen center seen by EPR) and very near a bond center in CaP and GaAs. This paper reviews these measurements and discusses the structures and their metastabilities. Comparison is made to EPR for Si and to theoretical studies. Recent results on the metastable and stable muonium centers in CuCl are discussed.
Analysis of Real-Time Hydrogenation data from P and N-Type Silicon
Authors: Seager Carleton H. , Anderson Robert A. 
Published: March 2011

AbstractHydrogenation of metal/thin oxide/p-type silicon and metal/n-type silicon diodes has been studied using high frequency capacitance profiling. In situ observations of acceptor and donor passivation were made while H ions were implanted through thin gate metallizations. Direct measurement of ion transits at a variety of electric fields establish that a unique mobility can be assigned to positive H ions, and modeling of low and high field data in both n and p-type samples is consistent with the notion that the positive charge state is occupied ~1/10 of the time. The time dependence of hydrogen penetration for both p and n-type diodes indicates that hydrogen is, in addition to being trapped at unpassivated shallow donors or acceptors, becoming immobilized at other sites in silicon. The density of these secondary trapping sites correlates well with the shallow dopant population suggesting that additional hydrogen atoms may become trapped near already-passivated dopant atoms.
Hydrogen Segregation at the Al/Si Interface Studied Using a Nuclear Resonant Reaction
Authors: Liu Joyce C. , Marwick A.D. , Legoues F.K. 
Published: March 2011

AbstractHydrogen segregation at the interface between an epitaxial Al film and a Si (111) substrate is studied using the 1H(15N, αγ)12C nuclear resonant reaction. Hydrogen depth profiles show that H atoms diffuse through the 1600 Å thick Al layer during 500 eV H implantation and are trapped at the Al/Si interface. The total amount of interface H is about 2 × 1015 /cm2 after a 1.4 × 1018 H/cm2 implantation, and the H atoms are narrowly distributed in the direction normal to the interface. During an isothermal anneal at 360 K, the amount of interface H decreases exponentially with annealing time; and during ramp annealing from 110 to 500 K, an abrupt release of the interface H is observed at temperature around 380 K. The release rates in both cases are controlled by a first order thermally activated de-trapping process with a binding energy of 0.86 eV/atom.
Surface and Bulk Properties which Influence Ion-Beam Hydrogenation of Silicon
Authors: Anderson Robert A. , Seager Carleton H. 
Published: March 2011

AbstractThe time evolution of dopant passivation in p and n-type silicon Schottky and MIS barriers has been investigated for low-energy H ions implanted directly into the silicon through a 400-Å front-electrode metallization. Knowledge of the dependence of the near-surface hydrogen concentration on time and experimental parameters is crucial to the analysis of these experiments. Hydrogenation effects are observed to vanish at ion energies below 800 eV, which suggests that the front electrode, rather than being a source of H, will behave as a sink for H diffusing in the silicon. Accordingly, we show that a steady-state H concentration proportional to the ion-deposition flux and deposition depth is established in a time interval less than a second near the electrode. Although some of the mobile H appears to be in a positively charged state, we calculate that the bias voltage applied to samples has only a small influence on the near-surface H concentration. An extensive study of the effects of sample temperature, beam flux, and ion energy supports these concepts and has revealed no evidence of ion-damage induced H trapping. The possible importance of H.H recombination is suggested by data obtained at the higher H concentrations.
The Electronic Structure of Interstitial Iron in Silicon
Authors: Thilderkvist A , Grossmann G , Kleverman M , Grimmeiss H G 
Published: March 2011

AbstractA donor-like spectrum in Fe-doped silicon has been studied by means of high-resolution Zeeman spectroscopy. Previous work had unambigouosly identified the center as the interstitial iron impurity and the spectrum was interpreted as due to the transitions , where an electron is excited to shallow effective-masslike donor states. In this paper, we can, by studying the transitions in a magnetic field, verify the effective-mass-like character of the loosely bound electron. Furthermore, we also obtain information on the impurity core whose level structure is reflected in the observed superposition of donor-hke Rydeberg series and whose g values determines the Zeeman splitting pattern.
Atomic Diffusion Processes in Silicon
Authors: Pantelides Sokrates T. 
Published: March 2011

AbstractThe mechanisms of self-diffusion and dopant impurity diffusion in silicon have been the subject of intense debate since the 1960’s. Until the mid-1980’s, there was only limited experimental information and virtually no theory. In the last five years, however, first-principles calculations of many key quantities and new experimental data have led to significant progress. This paper traces the major theoretical advances and the key experimental data that have resolved many controversies and have provided a fairly comprehensive picture of diffusion processes. Theory has also recently provided detailed microscopic information about the diffusion of interstitial hydrogen.
Pressure and Strain Effects on Diffusion
Authors: Antonelli A. , Bernholc J. 
Published: March 2011

AbstractWe have investigated, via parameter-free calculations, the effects of hydrostatic and nonhydrostatic strains on the energetics of defect formation and self-diffusion in silicon. The three microscopic mechanisms, vacancy, interstitial, and concerted exchange, have very similar activation enthalpies at zero pressure but exhibit different behavior with hydrostatic pressure. Our results suggest that experiments performed at different pressures can determine the relative contributions of each of these mechanisms. The calculations also show that the neutral Si vacancy has a negative relaxation volume, with the nearest neighbors of the vacancy relaxing inwards, in contrast to the Si (111) surface. Large nonhydrostatic strains, which are present in e.g. Si/GexSi1-x pseudomorphic heterostractures, substantially reduce the formation energy of the tetrahedral interstitial, but do not affect the formation energy of the vacancy. These findings suggest that, aside from being another useful tool for the investigation of self-diffusion in Si, nonhydrostatic strain may significantly affect annealing and impurity diffusion in strained heterostructures. In particular, the interstitial-assisted impurity diffusion may proceed more rapidly in Si lattice-matched to GexSi1-x, but be slowed down in GexSi1-x lattice-matched to Si. The compressed GexSi1-x layers may thus act as diffusion barriers for impurities diffusing with help of native interstitials, such as B or P.
Low-Temperature Diffusion of Dopants in Silicon
Authors: Fahey P. , Wittmer M. 
Published: March 2011

AbstractIt has been reported that diffusion of substitutional dopant atoms in silicon occurs during the formation of transition-metal suicides at temperatures below 300°C. By observing the diffusion enhancements of buried marker layers of Sb-, Ga-, Ge-, and B-doped silicon layers, we provide solid experimental evidence that the diffusion enhancement induced by Pd2Si formation at low temperatures is due to point defects generated by the suicide reactions. Diffusion enhancement is observed at temperatures as low as 200°C. We have found the surprising result that diffusion is asymmetric: diffusion occurs preferentially towards the suiciding interface.
Measurements of Enhanced Diffusion of Buried Layers in Silicon Membrane Structures During Oxidation
Authors: Dunham Scott T. , Agarwal Anuradha M. , Jeng Nanseng 
Published: March 2011

AbstractReported calculations of the diffusion coefficient of silicon self interstitials vary over several orders of magnitude at temperatures of interest for integrated circuit fabrication. In this work, we measure the enhanced diffusion of phosphorus buried layers while interstitials are injected at a wafer surface via thermal oxidation. The starting substrates were either float-zone silicon or Czochralski silicon with a pre-treatment to precipitate excess oxygen. The samples were prepared by implantation of phosphorus followed by the growth of a 40-60µm epitaxial layer. They were then etched anisotropically from the frontside or backside to yield membrane structures. Local oxidation was performed at 1100°C on either the frontside or backside of each wafer and buried layer diffusion was monitored, yielding information about interstitial diffusion in silicon and it’s dependence on bulk properties.
Migrations of Interstitial Atoms in Semiconductors (Surface Diffusion and Kick-Out Mechanism)
Authors: Wada Takao , Takeda Akihiro , Ichimura Masaya , Takeda Michihiko 
Published: March 2011

AbstractGe and Zn atoms were introduced into the unirradiated regions of Si at 150°C and GaAs wafers at 50°C, respectively by using the electron-beam doping method. The surfaces of Si and GaAs substrates were covered partially by the overlayers of Ge and Zn sheets, respectively. The only surfaces of the Ge and Zn sheets were irradiated locally. with high energy electrons at 7MeV with the fluences of 5×1017 – 1×1018 electrons cm-2 . Even at a distance of ~10mm from the irradiated overlayers in the Si and GaAs substrates, Ge and Zn atoms respectively, whose interstitials may migrate the unirradiated regions, were detected by SIMS measurements. PL signal due to band-to-acceptor (ZnGa ) transition at 1.48eV becomes observable after annealing at 800°C for 20mm in the unirradiated GaAs region, which is separated from Zn sheet by nearly 10mm.
High and Low Temperature Measurements of the Chromium Diffusivity in Silicon
Authors: Zhu J. , Barbier D. 
Published: March 2011

AbstractBy grouping high and low temperature diffusivity measurements in boron-doped silicon, a new diffusivity law for chromium in the 20–1050 °C temperature range has been established. High temperature diffusivities were deduced from erfc fits of chromium-boron pair profiles measured by means of Deep Level Transient Spectroscopy in chromium-plated substrates, after annealing for a short time in a lamp furnace. Low temperature diffusivities were derived from the association time constants of the chromium-boron pairing reaction in chromium-contaminated specimens. The whole data points were well fitted using the following expression for the diffusion coefficient: D= 2.6×10-3 exp(-0.81 ± 0.02 eV/kT). Because of the wide 1/T interval available, the migration enthalpy value is more accurate than the previous determinations using only high temperature diffusivity results.
Precipitation of Copper and Cobalt at Grain Boundaries in Silicon
Authors: Jendrich U. , Möller H. J. 
Published: March 2011

AbstractThe precipitation of copper and (radioactive) cobalt at low energy grain boundaries in polycrystalline silicon and bicrystals is investigated. The metals are diffused in from a surface source between 800 - 1000 °C and the precipitation after cooling down is studied by TEM (for Cu) and Mößbauer spectroscopy (for Co). The precipitates are metal suicides. For copper it is shown that they appear in form of colonies containing hundreds of precipitates with a particle size between 5-60 nm. In the grain boundary they nucleate preferentially at dislocations and steps. The distribution and size of the precipitates depend on the cooling rate after the diffusion. In the vicinity of the grain boundary the volume is depleted from the impurities.
Annealing of Ion Implanted Tin in Silicon: a RBS/ Channeling, Mössbauer Spectroscopy and Tem Investigation of Solubility and Residual Defects.
Authors: Kringhøj P. , Nylandsted Larsen A. , Petersen J. W. 
Published: March 2011

AbstractBy combining RBS/channeling, Mössbauer spectroscopy, and TEM measurements on implanted Sn in Silicon, the solid solubility has been determined at 1025°C, 1075°C, and 1188°C to be respectively, 6.1 , 4.8 , 3.1·1020 cm-3.
A Comparison of the Diffusivity of As and Ge in Si at high Donor Concentrations
Authors: Kyllesbech Larsen K. , Gaiduk P. , Nylandsted Larsen A. 
Published: March 2011

AbstractThe effect of high background doping (8×1019 - 5×1020 cm-3 ) on the diffusion of Ge and As in Si has been studied. A strong enhancement is found for As for donor concentrations higher than ~2×1020 cm-3 , but not for Ge. These experimental findings are discussed within the percolation model.
Diffusion of Ga Vacancies and Si in GaAs
Authors: Kahen K.B. , Lawrence D.J. , Peterson D.L. , Rajeswaran G. 
Published: March 2011

AbstractUsing the Si-pair diffusion formalism of Greiner and Gibbons, a new Si diffusion model is developed based on the dominant diffusion species being SiGa+ - VGa- pairs, where VGa is the Ga vacancy. In the model, the unknown parameters are the pair diffusion coefficient (Dp) and the equilibrium constant, which are fitted to the experimental data. Dp is also derived to be equal to one-half the Ga vacancy diffusivity. To verify this relation, an experiment to determine the VGa diffusivity, Dv, is performed. A relation for Dv of the form 0.962 exp(-2.72 eV/kT) cm2/s is obtained, and it is shown that the fitted Dp values are indeed approximately equal to 0.5 Dv.
Radiative and Non-Radiative Recombinations at Er Centers in GaAlAs
Authors: Benyattou Taha , Seghier Djelloul , Guillot Gerard , Moncorge Richard , Galtier Pierre , Charasse Marie-Noelle 
Published: March 2011

AbstractPhotoluminescence (PL) of Molecular Beam Epitaxy grown Er doped Ga 0.55Al0.45As has been studied under continuous and pulsed laser excitation . The observed PL lines are attributed to transitions from the first excited stated 4I13/2 to the ground state 4I15/2 . The life time of the 4I13/2 level is found to be 1 ms at 10K, which is comparable to the decay time observed in insulators.Using two-beam experiments we show that there are losses (Auger effect) that occur during the PL excitation.We propose the following model for the Er PL excitation process: excitons bound to Er are created and decay non radiatively by energy transfer to the rare earth (which is the cause of the Er related PL) or to free carriers by Auger effect (which is the cause of the observed losses).
Diffusion in Gallium Arsenide and GaAs-Based Layered Structures
Authors: Gösele U. , Tan T. Y. , Yu Shaofeng 
Published: March 2011

AbstractThe mechanisms of Ga self-diffusion can be derived from interdiffusion experiments in intrinsic and doped GaAs-based superlattices. These experiments allow to conclude that Ga self-diffusion in intrinsic and n-doped GaAs is carried by triply negatively charged gallium vacancies whereas in p-doped GaAs positively charged gallium self-interstitials dominate Ga self-diffusion. The diffusion mechanisms of Zn and Be are discussed with special emphasis on the difference between their in- and out-diffusion behavior which is due to diffusion-induced non-equilibrium point defects.
Effect of Local Atomic Configuration on DX Energy Level
Authors: Baba T. , Mizuta M. , Fujisawa T. , Yoshino J. , Kukimoto H. 
Published: March 2011

AbstractThe effects of specific local environments on DX centers were investigated for two different substitutional-site-donors of Si and Te in selectively-doped ordered-alloy samples. Capacitance transient technique under hydrostatic pressure was utilized for the determination of the DX energy-level structure. Downward movement of the energy levels for both Si- and Te-DX centers was observed when Al occupies the 2nd or 1st nearest neighbor site, respectively. A very large shift of the electron-emission activation-energy with pressure was found for the Te-DX centers surrounded by specific Al and Ga mixed-environments, whereas negligible shift for the Si-DX centers was observed regardless of the environment. These effects were discussed in relation to the lattice relaxation of the relevant DX centers.
DX-Center in Se-Doped AlxGa1-xAs
Authors: Hanak Thomas R. , Bakry Assem M. , Ahrenkiel Richard K. , Timmons Michael L. 
Published: March 2011

AbstractWe report the measurement of the thermal activation energy for the DX- center in Se-doped AlxGa1-xAs grown by metal-organic chemical vapor deposition (MOCVD) for different alloy compositions (x=0.19, 0.23, 0.27, 0.31). The peaks obtained from conventional DLTS are often broad or asymmetric with shoulders on one or both sides. These phenomena often arise from two or more traps which are active in the same temperature range.The capacitive transients are recorded digitally and analyzed directly by applying a nonlinear double exponential fitting routine to the data. This fitting produces two Arrhenius plots and yields the densities of the defect states. From the Arrhenius plots, the capture cross sections at infinite temperature and the thermal activation energies are calculated. These results are then used to simulate the DLTS spectra. Excellent agreement between real and simulated spectra is shown.
Poole Frenkel Effect on the DX Centers in III-V Ternary Alloys
Authors: Altelarrea H. , Bosch J. , Perez A. , Samitier J. , Morante J.R. 
Published: March 2011

AbstractThe dependence of the DX centers thermal emission rates on the electric field has been measured by Isothermal Transient Spectroscopy (ITS) and differential ITS (DITS) techniques. These techniques allow us to achieve a more accurate analysis of these defects than the DLTS, which ability for the study of DX centers is discussed. This dependence has been found to be mainly due to a Poole-Frenkel effect and is the cause of the non-exponentiality of the thermal emission transients.
Transient Current and Transient Capacitance Measurements of Defects in AlGaAs Hemts
Authors: Magno R. , Shelby R. 
Published: March 2011

AbstractThe defects present in AlGaAs high electron mobility transistor (HEMT) devices subjected to accelerated lifetime tests have been studied by transient current, and when possible, by transient capacitance techniques. By measuring transient source-drain currents following the application of a voltage pulse to the gate it is possible to perform deep level transient spectros-copy (DLTS) experiments on HEMT devices which are too small for the conventional capacitance DLTS. The capacitance and current spectra for both stressed and unstressed HEMTs contain the AlGaAs DX defect. The current DLTS spectra for stressed devices contain an additional feature which is not found in capacitance DLTS measurements on the stressed HEMTs. This additional current DLTS feature is anomalous in that the transient has a sign which is opposite to that expected for a majority carrier trap. The absence of the new defect in the capacitance DLTS suggests that the defect is located in the channel between the gate and either the source or the drain. The current DLTS line shape of the stressed induced defect depends upon the polarity and size of the source-drain voltage.