bluuebunny/crossref_metadata_2025_split huggingface dataset:
Equilibrium Configuration of Bi-Doped ZnO Grain Boundaries: Intergranular Amorphous Films
Authors: Wang Haifeng , Chiang Yet-Ming 
Published: April 2011

ABSTRACTIt is shown that the solid state equilibrium configuration of ZnO grain boundaries saturated with Bi-doping is a nanometer-thick amorphous film. Polycrystalline ZnO samples doped with Bi2O3 were studied using high resolution transmission electron microscopy (HRTEM) and dedicated scanning transmission electron microscopy (STEM). Samples were equilibrated below the eutectic temperature (Teutectic = 740°C) and at 1 atmosphere pressure, starting from three different initial states: one was cooled from above the eutectic temperature; a second was processed entirely below the eutectic temperature; and the third was de-segregated by applying high pressure (1 GPa) followed by annealing at 1 atmospheric pressure. In all instances, ZnO grain boundaries contain an amorphous film 1.0–1.3 ran in thickness, corresponding to a Bi excess equivalent to approximately one monolayer.
Point Defects Migration and Agglomeration in Si at Room Temperature: The Role of Surface and Impurity Content
Authors: Privitera V. , Coffa S. , Kyllesbech Larsen K. , Libertino S. , Mannino G. , Priolo F. 
Published: April 2011

ABSTRACTOur recent work on the room temperature migration and trapping phenomena of self-interstitials and vacancies in crystalline Si is reviewed. Spreading resistance profiling and deep level transient spectroscopy measurements were used to monitor the interaction of ion beam generated defects with dopant atoms, intrinsic impurities (i.e. O and C), pre-existing defect marker layers and sample surface. We have found that both interstitials and vacancies undergo fast long range migration which is interrupted by trapping at impurities and by recombination at defects or at the surface. Effective defect migration lengths as large as 5 μm at room temperature have been observed in highly pure, defect free epitaxial Si samples. A lower limit of 1×10−10 cm2/sec for the room temperature diffusivity of self-interstitials has been determined. Furthermore, by monitoring the migration and interaction processes of point defects injected through a mask, we have established that surface acts as an effective sink for the migrating Si self interstitials.
Thermal Evolution of Rectifier Speed and Deep Levels in Irradiated Silicon
Authors: Ntsoenzok E. , Desgardin P. , Blondiaux G. , Schmidt D. C. , Barbot J. F. , Blanchard C. , Renault P. O. 
Published: April 2011

ABSTRACTP+NN+ silicon rectifiers have been irradiated by protons and alpha particles. DLTS and reverse recovery time (the so called TRR) measurements were performed in both as-irradiated and annealed (400°C) samples. The evolution of implantation induced-centers with the annealing is not the same when using the two particles. For example, the concentration of the well known A center increases (decreases) with the annealing when protons (alpha particles) are used. On the other hand, the measurements of the TRR show that the rectifier speed decreases with the annealing in all cases studied.
Electrical Defects of Shallow (P+/N) Junctions Formed by Boron Implantation into Ge-Preamorphized Si-Substrates
Authors: Alquier D. , Benzohra M. , Boussaid F. , Olivie F. , Martinez A. 
Published: April 2011

ABSTRACTIn this paper, we report Current-Voltage (I-V), Capacitance-Voltage (C-V) and Deep Level Transient Spectroscopy (DLTS) measurements on ultra-shallow (p+/n) junctions obtained by boron implantation into crystalline and Ge preamorphized Si-substrates. Germanium implantations were carried out at the energies of 30, 60 and 150 keV at a dose of 1015 cm−2. Boron was then implanted at an energy of 3 keV at a dose of 1015 cm−2. Dopant activation was obtained by Rapid Thermal Annealing (RTA) performed at 950°C for 15s in a nitrogen ambient. The aim of this work is to study the relation that exists between a population of End-Of-Range (EOR) defects, measured by TEM, and electrical properties of the Ge preamorphized diodes. The electrical measurements allow us to give the conduction mechanism which dominates in the diodes. Moreover, DLTS measurements showed the presence of two majority-carrier traps in direct relation with the EOR defects, measured at Ec-0,22eV and Ec-0,47eV. The presence of energy-distributed G-R centers independent upon the preamorphization stage is also discussed. Nevertheless, high quality (p+/n) junctions can be obtained by this technology with a judicious choice of Ge implantation energy.
An Equilibrium Based Mean-Field Model for Diffusion in Solids With a Distributed Density of States
Authors: Franz A. J. , Gland J. L. 
Published: April 2011

ABSTRACTDetermination of transport mechanisms and energetics in amorphous silicon presents an interesting modeling challenge. Transport in amorphous silicon films is likely to involve energetically distributed traps and mobile species, as in the case of hydrogen and electron diffusion. Detailed kinetic models using discrete energy levels have been developed, however, the density of states of the diffusing species in amorphous silicon is likely to be continuous and distributed, due to the amorphous nature of the films. We have developed a mean-field, equilibrium based model which utilizes a continuous density of states for the diffusing species. The transport in amorphous silicon is modeled as a function of a gradient in the quasi-chemical potential, rather than concentration, of the diffusing species. The model is applicable when the local equilibration processes are fast relative to the transport process. This approach is extremely numerically efficient, as well as flexible, allowing for modeling of tracer experiments, such as deuterium diffusion in a-Si:H films, and possible changes in density of states with time, temperature, and diffusing species concentration. We demonstrate the utility of the model by simulating hydrogen evolution from a-Si:H films.
Ferroelectric films as a Fashion Object for Polycrystalline Film Investigation
Authors: Petrovsky V. , Anderson H.U. , Shumsky M. 
Published: April 2011

ABSTRACTBaxSr1-xTiO3 (BST), PbZrxTi1-xO3 (PZT) and two layer PZT-BST films were prepared on Pt, Si(100) and Si(111) substrates by a sol-gel method. XRD analysis shows that the PZT films on the Si(111) substrates tended to be preferentially oriented in the (110) direction. The nondestructive readout of the state of ferroelectric polarization was investigated by three methods: the pyroelectric effect, the non-linearity of the capacitance and the field effect in MOS structures. It is shown that all three methods provide nondestructive readout, and the choice between them depends on the intended use.
Accurate Depth Profiling of Ultra-Thin Oxide Films by Secondary
Ion Mass Spectrometry
Authors: Smith Stephen P. , Yang Ming Hong , Chia Victor K. F. 
Published: April 2011

ABSTRACTSurfaceSIMS depth profile measurements of dopants in silicon wafers with
thin thermal oxide layers are presented. Complete and accurate calibration
of these profiles requires layered data reduction to adjust for residual
matrix effects of a factor of two in the sputter rate and SIMS relative
sensitivity factor in SiO2 compared with bulk silicon. Properly
calibrated profiles show good agreement with expected ion implant profile
shapes, and can reveal dopant pile-up at SiO2/Si interfaces
(phosphorus, for example). Measured SurfaceSIMS profiles of B doping within
the first 10 nm of the substrate Si of experimental large area MOS
capacitors show good agreement with dopant profiles independently obtained
from experimental C-V data.
Thermoelectric Properties of P-Type (Bi1−xSbx)2Te3 Fabricated by Mechanical Alloying Process
Authors: Jung Boo Yang , Choi Jae Shik , Oh Tae Sung , Hyun Dow-Bin 
Published: April 2011

AbstractThermoelectric properties of polycrystalline (Bi1−xSbx)2Te3 (0.75 ≤ x ≤ 0.85), fabricated by mechanical alloying and hot pressing methods, have been investigated. Formation of (Bi0.25Sb0.75)2Te3 alloy powder was completed by mechanical alloying for 5 hours at ball- to-material ratio of 5: 1, and processing time for (Bi1−xSbx)2Te3 formation increased with Sb2Te3 content x. When (Bi0.25Sb0.75)2Te3 was hot pressed at temperatures ranging from 300°C to 550°C for 30 minutes, figure-of-merit increased with hot pressing temperature and maximum value of 2.8 × 10−3/K could be obtained by hot pressing at 550°C. When hot pressed at 550°C, (Bi0.2Sb0.8)2Te3 exhibited figure-of-merit of 2.92 × 10−3/K, which could be improved to 2.97 × 10−3/K with addition of 1 wt% Sb as acceptor dopant.
Microstructural and Thermoelectric Properties of P-Type Te–Doped Bi0.5Sb1.5Te3 And N-Type SbI3-Doped Bi2Te2.85Se0.15 Compounds
Authors: Seo J. , Park K. , Lee C. , Kim J. 
Published: April 2011

AbstractThe p-type Te-doped Bi0.5Sb1.5Te3 and n-type SbI3-doped Bi2Te2.85Se0.15 thermoelectric compounds were fabricated by hot pressing in the temperature range of 380 to 440 °C under 200 MPa in Ar. Both the compounds were highly dense and showed high crystalline quality. The grains of the compounds were preferentially oriented and contained many dislocations through the hot pressing. The fracture path followed the transgranular cleavage planes, which are perpendicular to the c-axis. In addition, with increasing the pressing temperature, the figure of merit was increased. The highest values of figure of merit for the p- and n-type compounds, which were obtained at 420 °C, were 2.69 × 10−3/K and 2.35×10−3/K, respectively.
Searching for New Thermoelectrics in Chemically and Structurally Complex Bismuth Chalcogenides
Authors: Chung Duck Young , Hogan Tim , Schindler Jon , Iordanidis Lykourgos , Brazis Paul , Kannewurf Carl R. , Chen Baoxing , Uher Ctirad , Kanatzidis Mercouri G. 
Published: April 2011

AbstractA solid state chemistry synthetic approach towards identifying new materials with potentially superior thermoelectric properties is presented. Materials with complex compositions and structures also have complex electronic structures which may give rise to high thermoelectric powers and at the same time possess low thermal conductivities. The structures and thermoelectric properties of several new promising compounds with K-Bi-Se, K-Bi-S, Ba-Bi- Te, Cs-Bi-Te, and Rb-Bi-Te are reported.
The Growth of Type-II Infrared Laser Structures
Authors: Yang M. J. , Moore W. J. , Bennett B. R. , Shanabrook B. V. , Cross J. O. 
Published: April 2011

AbstractThe MBE growth temperature for InAs/InGaSb/InAs/AlSb mid-infrared lasers has been studied. It is found that the best growth temperature is between 370°C and 420°C. A growth temperature above this range will result in excessive interlayer mixing, which degrades the radiative efficiency.
Recent Improvements in Dry Etching of Hg1−xCdxTe by CH4 Based Electron Cyclotron Resonance Plasmas
Authors: Seelmann-Eggebert M. , Rar A. , Zimmermann H. , Meisen P. 
Published: April 2011

AbstractSignificant improvements of a previously reported etching process [1] for Hg1−xCdxTe have been achieved with respect to etch rate, surface morphology and surface stoichiometry by optimization of the process parameters. The gas phase and surface reactions driving the etching process have been analyzed by combined optical and electrical characterization of the plasma and surface analyses of the samples. A reaction scheme is suggested which allows to model and upscale the process in a consistent manner.
Improved CdZnTe detectors grown by vertical Bridgman process
Authors: Lynn K. G. , Weber M. , Glass H. L. , Flint J. P. , Szeles Cs. 
Published: April 2011

AbstractThe γ ray (57Co) and a particle (241Am) detector response of Cd1−xZnxTe crystals grown by vertical Bridgman technique was studied under both positive and negative bias conditions. Postgrowth processing was utilized to produce a high-resistivity material with improved chargecollection properties. Samples of various Zn concentrations were investigated by I–V measurements and thermally stimulated spectroscopies to determine the ionization energies of deep levels in the band gap. When the post-processing conditions were optimized the lowenergy tailing of the γ-ray photopeaks was significantly reduced and an energy resolution of under 5% was achieved for the 122 keV γ-photon line in crystals with x=0.2 Zn content at room temperature. A peak to background ratio of 14:1 for the 122 keV photopeak from 57Co was observed on the best sample, using a standard planar detection geometry. The low-energy 14.4 keV X-ray line could also be observed and distinguished from the noise.
Study on Deep Level Traps in p-HgCdTe With Dltfs
Authors: Kawata S. , Sugiyama I. , Kajihara N. , Miyamoto Y. 
Published: April 2011

AbstractWe studied the characteristics of deep-level traps in p-type HgCdTe diodes using the Deep Level Transient Fourier Spectroscopy (DLTFS) method. For both holes and electrons, two types of traps were observed. The DLTFS signal intensity of one type of trap increased with the carrier density in the HgCdTe, while the other did not exhibit a monotonic increase. While measuring the stability of these traps during cooling cycles, the DLTFS signal intensity of the first group was almost constant while that of the latter fluctuated with every cooling cycle. Stable traps originated from Hg vacancies, unstable traps are attributed to vacancy-impurity complex defects.
Modeling Interdiffusion in Superlattice Structures
Authors: Gass Richard G. , Jackson Howard E. 
Published: April 2011

AbstractCompositional interdiffusion in Al0.3 Ga0.7 As/GaAs superlattices induced by Si focused ion beam implantation and subsequent rapid thermal annealing is modeled using a set of diffusion equations which take into account the dynamics of the vacancy spatial profile. The inclusion of a new phenomenological term, which depends on the time derivative of the vacancy concentration spatial profile, provides good agreeement with experiment.
Cation Interdiffusion in GaInP/GaAs Single Quantum Wells
Authors: Micallef Joseph , Brincat Andrea , Shiu Wai-Chee 
Published: April 2011

AbstractThe effects of cation interdiffusion in Ga0.51In0.49P/GaAs single quantum wells are investigated using an error function distribution to model the compositional profile after interdiffusion. Two interdiffusion conditions are considered: cation only interdiffusion. and dominant cation interdiffusion. For both conditions the fundamental absorption edge exhibits a red shift with interdiffusion, with a large strain build up taking place in the early stages of interdiffusion. In the case of cation only interdiffusion, an abrupt carrier confinement profile is maintained even after significant interdiffusion, with a well width equal to that of the as-grown quantum well. When the interdiffusion takes place on two sublattices. but with the cation interdiffusion dominant, the red shift saturates and then decreases. The model results are consistent with reported experimental results. The effects of the interdiffusion-induced strain on the carrier confinement profile can be of interest for device applications in this material system.
Disorder-Delineated AlGaAs/GaAs Quantum-Well Phase Modulator
Authors: Choy Wallace C. H. , Weiss Bernard L. 
Published: April 2011

AbstractModeling is used to investigate waveguide phase modulators, with 0.5 μm and 1 μm quantum well active regions which are defined by implantation induced disordering. By controlling the extent of the interdiffusion in the lateral claddings, the refractive index difference between the core and claddings is used to provide single mode operation. The performance of the phase modulator is studied in terms of optical confinement, phase change per unit voltage per unit length, chirping property and absorption loss. Our result shows that the 0.5 μm one is a more efficient structure and its absorption loss can be reduced by increasing the applied field from 50 kV/cm to 100 kV/cm.
ZnGeP2 and its Relation to Other Defect Semiconductors
Authors: Vere A. W. , Taylor L. L. , Smith P. C. , Flynn C. J. , Saker M. K. , Jones J. 
Published: April 2011

AbstractThe paper discusses progress in the development of ZnGeP2 (ZGP) for optical parametric oscillator (OPO) applications and draws parallels with other semiconductors with volatile components, in which the presence of lattice defects gives rise to non-stoichiometry. In particular, attention is drawn to the microprecipitation which accompanies deviation from stoichiometry. In other materials this has been shown to result in spatial non-uniformity in the density of point defects.
Extra-Wide Tuning Range Mid-Ir Optical Parametric Generator Pumped by Er-Laser Pulses
Authors: Vodopyanov K. L. 
Published: April 2011

AbstractInfrared pulses, continuously tunable in the 3–19 μm range, and with up to 1MW peak power, have been achieved using single-stage frequency conversion in a travelling-wave optical parametric generator (OPG) based on ZnGeP2, CdSe and GaSe crystals. The OPG was pumped by 100ps pulses from an actively mode-locked, Q-switched and cavity dumped 2.8 μm Cr,Er:YSGG laser. The quantum conversion efficiency reached 17%.
Improved CdZnTe detectors grown by vertical Bridgman Process
Authors: Lynn K. G. , Weber M. , Glass H. L. , Flint J. P. , Szeles Cs. 
Published: April 2011

AbstractThe γ ray (57Co) and α particle (241Am) detector response of Cdl-xZnxTe crystals grown by vertical Bridgman technique was studied under both positive and negative bias conditions. Postgrowth processing was utilized to produce a high-resistivity material with improved chargecollection properties. Samples of various Zn concentrations were investigated by I-V measurements and thermally stimulated spectroscopies to determine the ionization energies of deep levels in the band gap. When the post-processing conditions were optimized the lowenergy tailing of the γ-ray photopeaks was significantly reduced and an energy resolution of under 5% was achieved for the 122 keV γ-photon line in crystals with x=0.2 Zn content at room temperature. A peak to background ratio of 14:1 for the 122 keV photopeak from 57Co was observed on the best sample, using a standard planar detection geometry. The low-energy 14.4 keV X-ray line could also be observed and distinguished from the noise.
New CdTe Quantum Sensor, With Improved Spatial Resolution, for Fast X-Ray and γ-Ray Imaging
Authors: Gerstenmayer Jean-Louis , Bonnin Olivier , Gerbe Vincent , Glasser Francis , Peyret Olivier 
Published: April 2011

AbstractWe have designed and tested a new compact, very sensitive (>1 μRad), X-ray quantum sensor for high energy (0.5 -10 MeV) flash imaging. Monte Carlo simulations have been computed for several interesting detector materials (CdZnTe, HgI2-a, BGO, CsI, LSO...). From these calculations, we obtain general design rules and curves which allow one to optimize the pixel size of a sensor to the dose levels. An experimental CdZnTe detector array and its performance is presented.
Radiation Source Dependence of Degradation in Mosfets on SIMOX Substrate
Authors: Hakata T. , Ohyama H. , Simoen E. , Claeys C. , Takami Y. , Kawamura K. , Miyahara K. , Hososhima M. 
Published: April 2011

AbstractResults are presented for the first time of a study on the degradation of the electrical performance of MOSFET's processed on SIMOX substrates and subjected to a 220-MeV carbon irradiation. For the n-MOSFETs an unstable increase of the drain current in linear operation is found, while for the p-MOSFETs, a drastic reduction is observed, both in linear operation and in saturation. The radiation damage is also compared to the results for 1-MeV electrons, 1-MeV fast neutrons and 20-MeV alpha rays. The differences in the damage coefficients are explained by the differences in the number of knock-on atoms and the nonionizing energy loss (NIEL). The recovery behavior of the device performance by isochronal annealing is also reported.
High Purity Liquid Phase Epitaxial GaAs For Radiation Detectors
Authors: Wynne D. I. , Tull C. S. Rossington , Haller E. E. 
Published: April 2011

AbstractWe report on the growth of high purity n-GaAs using Liquid Phase Epitaxy (LPE) and the fabrication of room temperature p-i-n radiation detectors. Our epilayers are grown from a Ga solvent in a graphite boat in a pure hydrogen atmosphere. Growth is started at a temperature of approximately 800 °C. Our best epilayers show a net-residual-donor concentration of 2×1013 cm−3, confirmed by Hall effect measurements. The residual donors have been analyzed by far infrared spectroscopy and found to be sulfur and silicon. Epilayers with thicknesses of up to 120 µm have been deposited on 650 µm thick semi-insulating GaAs substrates and on 500 µm thick n+-type GaAs substrates. We report the results obtained with Schottky barrier diodes fabricated from these high purity n-type GaAs epilayers and operated as X-ray detectors. The Schottky barrier contacts consisted of evaporated circular gold contacts on epilayers on n+ substrates. The ohmic contacts were formed by evaporated and alloyed Ni-Ge-Au films on the back of the substrate. Several of our diodes exhibit currents of the order of 1 to 10 nA at reverse biases depleting approximately 50 µm of the epilayer. This very encouraging result, demonstrating the possibility for fabricating GaAs p-i-n diodes with depletion layers in high purity GaAs instead of semi-insulating GaAs, is supported by similar results obtained by several other groups. The consequences of using high purity instead of semi-insulating GaAs will be much reduced charge carrier trapping. Diode electrical characteristics and detector performance results using 55Fe and 241Am radiation will be discussed.
An Approach to Sub-Pixel Spatial Resolution in Room Temperature X-Ray Detector Arrays with Good Energy Resolution
Authors: Warburton W. K. 
Published: April 2011

AbstractIn this paper we examine a recently proposed concept for obtaining sub-pixel spatial resolution in compound semiconductors where hole transport properties are relatively poor. [1] This approach uses weighted sums and differences of local pixel signals to extract both accurate x-ray energy estimates and interpolate location at the sub-pixel level. A simple analysis, including noise estimates, suggests the possibility of obtaining locations at the 50–100 micron level using 1–2 mm wide stripe electrodes while obtaining 1–2% energy resolution for x-rays up to 100 keV. Following this examination, we will present the most recent experimental results from our program to develop electronics to implement this scheme.
Synthesis of New Multifunctional Polymers inCorporating BIS-(Diphenylamino)Diphenylpolyene Moieties
Authors: Spangler C. W. , Faircloth T. , Elandaloussi E. H. , Reeves B. 
Published: April 2011

AbstractA series of bis-(diphenylamino)diphenylpolyenes containing up to eight double bonds has been synthesized, both as parent model compounds, and functionalized for attachment as pendant chromophores. Oxidative doping of these new materials yields exceptionally stable bipolaronlike dications, even at the triene level. These new materials show promise as bimechanistic optical limiters by reverse saturable absorption and by 2-photon absorption.