bluuebunny/crossref_metadata_2025_split huggingface dataset:
Explosive Thermal Decomposition Mechanism of NTO
Authors: Beardall David J. , Botcher Tod R. , Wight Charles A. 
Published: April 2011

AbstractThe initial step of the thermal decomposition of NTO (5-nitro-2,4-dihydro-3H-1,2,4- triazol-3-one) is determined by pulsed infrared laser pyrolysis of thin films. Rapid heating of the film and quenching to 77 K allows one to trap the initial decomposition products in the condensed phase and analyze them using transmission Fourier-transform infrared spectroscopy. The initial decomposition product is CO2; NO2 and HONO are not observed. We propose a new mechanism for NTO decomposition in which CO2 is formed.
Time Resolved Emission Studies of Aluminum and Water High Pressure Reactions
Authors: Brown C. A. , Russell T. P. 
Published: April 2011

AbstractThe detonation of underwater explosives is a complex problem involving a temporally dependent heterogeneous reaction regime of oxidizer reactions and high pressure metal combustion. For simplicity, underwater explosions may be described as a two stage reaction process. First, the oxidizing material detonates to produce species under extreme conditions of temperature (up to 5000 K) and pressure (up to 10 GPa). The chemical energy produced from this reaction is transferred to the bulk water as three forms of work: (I) shock, (2) heat, and (3) initial bubble formation. Second, the species produced by the oxidizer detonation form a high pressure and high temperature reactive fluid that surrounds the solid particles. The solid particles are primarily consumed while the pressure is decreasing from 10 GPa to 0.1 GPa at a reaction temperature in excess of 3200 K. The secondary reaction of the solid particles produces a lower energy shock and a pressure response that reinforces the initial energy delivered to the bulk water medium. The ability to tailor this late energy release between shock and bubble formation is dependent on the reaction time and chemistry of the solid particle under extreme conditions. We present a series of single-shot time resolved emission experiments that probe the reaction of aluminum particles under extreme conditions. The temporal behavior of the observed species is used to gain insight into the chemical reaction mechanism that leads to the formation of A1203 during underwater detonations.
High Pressure Equation of State for Fe2O3
Authors: Zerilli Frank J. , Jones Hermenzo D. 
Published: April 2011

AbstractA Debye-Gruneisen equation of state for hematite (Fe2O3) was developed for use in studying the high pressure solid state reaction Al + Fe2O3 → Fe + A12O3. A simple, single Curie temperature Curie-Weiss ferromagnetic term was used to account for the complex antiferromagnetic contributions to the entropy and specific heat. In the absence of information on the variation of Curie temperature with pressure, it is taken to be constant, so that the antiferromagnetism makes no contribution to the pressure-volume equation of state.
Charge Densities and Electrostatic Potentials for Energetic Materials
Authors: Pinkerton A. A. , Martin A. 
Published: April 2011

AbstractHigh resolution (sinθ/λ < 1.34 Å−1), low temperature (85 K) X-ray diffraction data has been used to map the deformation density and the derived electrostatic potential for three dinitramide salts. The traditional presentation of contour maps has been replaced with 3D views of the molecule. A comparison of the dinitramide ions from each salt is presented.
Optical Properties of RDX and HMX
Authors: Isbell R. A. , Brewster M. Q. 
Published: April 2011

AbstractOptical properties of RDX (cyclotrimethylene-trinitramine) and HMX (cyclotetramethylenetetranitramine) were obtained from 2.5 to 18 gtm using scattering-corrected KBr pellet-FTIR transmission spectrometry. Absorption index (k) was measured directly and refractive index (n) was deduced using dispersion theory. At 10.6 μm the absorption coefficients were RDX, 2800 cm−1 and HMX, 5670 cm−1.
Three Color Detection in the Charge Integration Regime by ATCD for Large Area Applications
Authors: Irrera F. , Lemmi F. , Palma F. 
Published: April 2011

AbstractLarge area color image scanners are currently being widely investigated. The a-Si:H/a-SiC:H Adjustable Threshold Color Detector (ATCD) recently presented by the authors is suitable for greatly simplifying the structure of the arrays since ATCDs have just two external electrical connections. This makes possible to use the row-column addressing of pixels.In this work, the transient operation of ATCDs in the charge integration regime is discussed. Charge integration is operated by photocurrent discharging the three series connected capacitances which compose the device structure. The penetration depth of the incident radiation depends on the wavelength and determines which of the three capacitances is discharged. The applied bias voltage determines the polarization of the three junctions and the three capacitance actually sensed. Correct blue, green and red light detection is shown in the read-out transients and the read-out and saturation times are presented. Finally design rules of the device and read-out system are given in order to achieve a correct detection of the three colors.
A New Type of Cylindrical a-Si:H X-Ray Detector
Authors: Link D. , Keppner H. , Chabloz P. , Shah A. , Germond J.-F. , Haefliger J.- M. , Pochon Y. , Frosio G. 
Published: April 2011

AbstractThe present paper describes a new type of cylindrical X-ray detector based on thick amorphous silicon diodes. The authors report on the successful development of these detectors that have diameters as small as 3mm. The effect of silane dilution in hydrogen on deposition rate, powder formation, layer adhesion and detector performance is discussed. A set of deposition parameters is presented, that allows a reasonable compromise between the mentioned effects. First prototypes of this type of dosimeter have been characterised with the radiation from a 60Co source in a hospital. The corresponding results and interpretation are given in this paper.
Progress Towards a High-Resolution X-Ray Photon Counter
Authors: Apte R. B. , Nickel N. , Street R. A. , Weisfield R. , Wu J. X.-D. , Ready S. , Nguyen M. , Nylen P. 
Published: April 2011

AbstractProgress towards x-ray shot-noise limited imaging with resolution superior to film is reported for a large format amorphous silicon imaging system containing 1536x 1920 pixels. Improvements over previous work include the development of a complete system, the use of charge-sensitive amplifiers, and careful control of extrinsic noise. A charge-sensitive amplifier with 1000:1 dynamic range is used to detect the signal in the presence of a large parasitic capacitance, 95pF, which both increases the intrinsic noise in the amplifier and technical noise coupled from other sources. The RMS noise level, 4200 e, is within two octaves of single x-ray counting.
Amorphous Silicon-Carbon Thin Film P-I-N Structures for Liquid-Crystal Spatial Light Modulators
Authors: Feoktistov N. A. , Ivanova N. L. , Morozova L. E. , Nikulin Yu. A. , Onokhov A. P. , Pevtsov A. B. , Schwarz R. 
Published: April 2011

AbstractPhotoaddressed spatial light modulators (PSLM) based on nematic liquid crystals using hydrogenated amorphous silicon-carbon films (a-Si1-xCx,:H) and p-i-n structures as photosensitive layers are designed and studied. It is shown that an application of a-Si1-xCx:H p-i-n diodes greatly improved the operation speed of a PSLM, increased the film transparency and decreased the absorption of the red readout light. As a result, the readout light intensity could become ≈ 20 times larger. The maximum diffraction efficiency of the PSLM was achieved for a write-in light intensity of 40μLW/cm2, with a resolution (FWHM) of the diffraction efficiency of 54 mm-1. The optical response of the PSLM was observed in the frequency range from 1 Hz to 100 Hz.
Probe of Field Collapse in a-Si:H Solar Cells
Authors: Wang Qi , Crandall Richard S. 
Published: April 2011

AbstractWe study the effect of illumination intensity on solar cell performance in a-Si:H solar cells. We find that the fill factor strongly depends on light intensity. As we increase the illumination intensity from low levels to one sun we observe a decrease in fill factor of approximately 15% in as grown cells. We attribute this effect to electric field collapse inside the cell. We propose that photogenerated space charge (free and trapped charge) increases with light intensity and causes field collapse. We describe the origin of space charge and the associated capacitance - photocapacitance. We measure the photocapacitance as a barometer to probe the collapsed field. We obtain a good agreement between photocapacitance experiments and theory. We also explore the light intensity dependence of photocapacitance and explain the decrease of FF with the increasing light intensity.
Electrical Transport Mechanisms in p+a-SiC:H/n c-Si Heterojunctions: dark J-V-T Characteristics
Authors: van Cleef M. W. M , Philippens M. W. H. , Rubinelli F. A. , Kolter M. , Schropp R. E. I. 
Published: April 2011

AbstractIn the present paper we show results of dark current-voltage measurements performed on p+ a- SiC:H/n c-Si heterojunction diodes at various temperatures (100–400K). We investigated the voltage derivative of these J-V curves in order to the distinguish possible current transport mechanisms. It was found that for low temperatures (<300K), the current is determined by recombination of carriers in the crystalline silicon, whereas at high temperature (>300 K), by a tunnelling mechanism. At room temperature, both mechanisms contribute to the current. By using an equivalent circuit model and detailed numerical simulations we have interpreted our experimental characteristics. The simulations done at room temperature, show that at low forward bias voltage the current is controlled by recombination in the crystalline silicon and that at high forward bias voltage by a combination of multi-step tunnelling and a-SiC:H series resistance. For interface state densities equal to or higher than 1012 cm−2, the recombination was found to be dominated by the states at the amorphous-crystalline silicon interface.
Defect Density-of-states in a-Si:H TFTs
Authors: Globus T. , Gelmont B. , Mattauch R. J. , Sun L. Q. 
Published: April 2011

AbstractThe novel version of the field effect conductivity method for the direct density-of-states (DOS) determination has been developed. The combination of both, a new analytical solution, in the form of integral equation which relates the surface potential to the gate voltage, and new data-analysis algorithms allows one to solve the problem by using the results of measurements of TFT quasi-static transfer characteristics. This sensitive, and easy to use, method provides the detailed information on the defect density in the gap of hydrogenated Si. The ability of this technique to extract parameters of the TFT, including the flat band voltage, from the dependence of the surface potential on the gate voltage, and to resolve fine-scale features in the midgap DOS of a-Si:H has been demonstrated.We have shown that the dependence of the DOS on the energy in the range 0–0.15 eV from the conduction band is close to the exponent, while deeper in the gap, the DOS can be described as a series of localized defect bands with amplitude values in the range 1016 cm−3 eV−1-2×1018 cm−3 eV−1.The integrated charge density and the surface potential as functions of gate voltage have been investigated. The difference between the surface potential and activation energy from temperature dependence of drain current has been discussed. The short-time current relaxation and metastable defect transformations have been studied and analyzed.
Highly Conductive p-type Microcrystalline Silicon Thin Films
Authors: Heintze M. , Schmitt M. 
Published: April 2011

AbstractThe plasma deposition of boron doped microcrystalline films was optimized with respect to crystallinity and doping efficiency. High room temperature conductivities up to 39 Scm−1 were achieved under condition when the energy of positive ions impinging on the growth surface is minimized.
New Results of nc-Si:H Films Prepared by Hydrogen-Diluted Silane in a Triode Pecvd System
Authors: Qin Hua , Chen Kunji , Huang Xinfan , Li Wei , Ikuta Kazuyuki , Matsuda Akihisa , Tanaka Kazunobu 
Published: April 2011

AbstractWe report new results on microstructures and electronic properties of nanocrystalline silicon (nc-Si:H) films prepared by a triode PECVD method with a hydrogen diluted silane plasma. The transition from a-Si:H to nc-Si:H was obtained by varying the ratio of H2 to SiH4 while the bias of the grid electrode was fixed at 100.V with respect to the substrate. The threshold value of [H2]/[H2 ]+[SiH4] is about 93.3%. With increasing value of [H2]/[H2]+[SiH4], the volume fraction of crystallinity in nc-Si:H films increased from 12% to 50%, while the average grain size remaind constant. This is quite different from the structures of samples prepared by the conventional diode PECVD with H2 dilution. The traveling-wave technique was applied to study the transport properties of nc-Si:H films, and experimental results confirmed percolation transport in nc-Si:H films.
STM Observation on the Initial growth of Amorphous and Microcrystalline Silicon Films
Authors: Ikuta K. , Toyoshima Y. , Yamasaki S. , Matsuda A. , Tanaka K. 
Published: April 2011

AbstractDirect nanoscale observation on the nucleation and growth of hydrogenated amorphous and microcrystalline silicon on graphite substrates was made using scanning tunneling microscopy, atomic force microscopy, and Raman scattering spectroscopy. Nucleation of hydrogenated silicon clusters is initiated through the nucleation sites created by reactive hydrogen species coming from the source gas plasma. The difference in spatial distribution of nucleated clusters at the initial stage of deposition between a-Si:H and μc-Si:H is ascribed to the difference in the number density of nucleation sites which results in difference in the diffusion length of a SiH3 radical at the initial stage of deposition on the graphite substrate. The RMS roughness of μc-Si:H films is larger than that of a-Si:H when the film thickness is larger than 10 Å, which is opposite to the behavior at the initial nucleation stage on the graphite substrate.
Chemical Properties of A-Si:H Interface Layers on Oxide-Covered and Hydrogen-Terminated Silicon
Authors: Knobloch Jürgen , Hess Peter 
Published: April 2011

AbstractHigh quality a-Si:H films were deposited by pulsed VUV (157nm) laser CVD, allowing digital control of the deposition process. Nucleation and growth on native oxide-covered Si (100) and on H-terminated Si (111) surfaces were studied in situ by FTIR transmission spectroscopy with sub-monolayer sensitivity. The film thickness was monitored simultaneously using a quartz crystal microbalance (QCM) with comparable resolution. The in situ spectra reveal that the nature of the substrate surface significantly influences the hydrogen bonding configuration in the interface region. In both cases the assumed cluster growth during the initial stage is characterized by a band around 2100cm−1, which is assigned to SiHX (x = 1 – 3) surface modes. This band broadens until the clusters coalesce and band saturation occurs. At this time a second band starts to grow at 2000cm−1, which is attributed to bulk SiH bonds. Difference spectra calculated for layers at different depths with definite thickness and the deconvolution of the broad feature observed during the very first stage of film growth indicate the existence of a hydrogen-rich layer at the substrate surface whose composition and thickness depend on the properties of the substrate surface.
Tritium in Amorphous Silicon
Authors: Sidhu L. S. , Kosteski T. , O'Leary S. K. , Gaspari F. , Zukotynski S. , Kherani N. P. , Shmadya W. 
Published: April 2011

AbstractPreliminary results on infrared and luminescence measurements of tritium incorporated amorphous silicon are reported. Tritium is an unstable isotope that readily substitutes hydrogen in the amorphous silicon network. Due to its greater mass, bonded tritium is found to introduce new stretching modes in the infrared spectrum. Inelastic collisions between the beta particles, produced as a result of tritium decay, and the amorphous silicon network, results in the generation of excess electron-hole pairs. Radiative recombination of these carriers is observed.
Hydrogen Density of States and Defects Densities in a-Si:H
Authors: Deane S C , Powell M J , Robertson J 
Published: April 2011

AbstractFurther details are given of a unified model of the hydrogen density of states and defect pool of a-Si:H. The model is compared to other defect models and extended to describe a-Si alloys and the creation of valence band tail states during growth.
Plasma Induced Changes to TCO/a-Si:H Interfaces
Authors: Wallinga J. , Knoesen D. , Hamers E. A. G. , Sark W. G. J. H. M. Van , Weg W. F. Van Der , Schropp R. E. I. 
Published: April 2011

AbstractThe effect of ion bombardment on the plasma enhanced chemical vapor deposition of a-Si:H and on TCO/a-Si:H interface reactions has been studied. An external DC-bias voltage is applied to the deposition plasma in order to change the ion flux and ion energy. The deposition rate increases with the applied bias-voltage i.e. with the plasma potential. Hydrogenated amorphous silicon is grown on natively rough transparent conductive oxide. With cross-sectional transmission electron microscopy lower density regions can be observed in the a-Si:H in all sharp valleys of the TCO. The appearance of the lower density regions changes under influence of the ion bombardment. The observed changes are in agreement with the changes observed when no ion bombardment is present at all, like in a hot wire chemical vapor deposition process. The increased ion bombardment did not give rise to observable chemical reactions at the TCO/a-Si:H interface.
Nonlinear Dependence of μeτe on Subgap Absorption in Pulse and cw Light-Soaked a-Si:H
Authors: Hata Nobuhiro , Ikeda Toru , Matsuda Akihisa 
Published: April 2011

AbstractWe report new results from subgap absorption and transport measurements on pulse and continuous (cw) light-soaked a-Si:H which include that (1) the mobility-lifetime product of electrons (μeτe) shows the same dependence on defect subgap absorption irrespective of whether the sample was soaked by pulse or continuous lights, but that (2) the dependence of μeτe on defect subgap absorption is not linear. These results are compared with annealing energy distribution of light-induced defects, and discussed in terms of (1) annealing energy (Eann) distribution of light-induced defects (LIDs), and of (2) photo-induced structural change.
Bonding Defects in Hydrogenated Amorphous Silicon
Authors: Lucovsky G. , Yang H. 
Published: April 2011

AbstractA mechanism for charged-carrier-trapping-inducedde fect metastability in hydrogenated amorphous silicon (a-Si:H) and in hydrogenated amorphous silicon alloys containing relatively high concentrations of oxygen and/or nitrogen atoms (a-Si:X:H, X = O or N) is described. The experimental results that identified this defect metastability mechanism were i) differences in the Staebler-Wronski effect in a-Si:H and a-Si:N:H alloys prepared from N2 and NH3 source gases by remote plasma-enhanced chemical-vapor deposition, and ii) differences in defect generation at N-atom terminated Si-SiO2 interfaces prepared from NH3 and N2O.
Defect Equilibration in Amorphous Silicon Films Submitted to High Intensity Illumination
Authors: Godet C. , Cabarrocas P. Roca i 
Published: April 2011

AbstractIn plasma-deposited a-Si:H films, the increase of the metastable defect density produced by high-intensity illumination usually follows a stretched-exponential time-dependence, with a characteristic time τSE and a steady-state value Nss. For a wide range of deposition conditions, we have observed that both parameters depend on the material properties. The strong correlation between Nss and the monohydride [SiH]2000 density, reported previously, has been interpreted as due to the trapping of metastable H atoms at specific sites.In this study of the kinetics of defect equilibration under high-intensity illumination, we find two groups of a-Si:H films with fast and slow kinetics, respectively. These two groups display a very different dependence of the defect creation rate as a function of the optical gap. For the fast kinetics films, we emphasize the critical influence of the Urbach energy Eu deduced from the exponential optical absorption edge (1/τSE increases as a function of Eu). The slow kinetics films are characterized by a high nanovoid density evidenced by their SiHx infrared signature at 2090 cm-1. The results are discussed in relation to the medium-range H motion.
Partial Depletion Region Collapse and its Impact on Transient Capacitance Measurements
Authors: Lips Klaus , Unold Thomas , Xu Yueqin , Crandall Richard S. 
Published: April 2011

AbstractWe investigate capacitance transients under various experimental conditions on a number of different amorphous silicon Schottky barrier device structures. The samples differ mainly in their back contact configuration, which is non-ohmic for one type of sample and ohmic for the second type of samples. Anomalous transients can be observed for all samples regardless of the back contact if the depletion region is only partially collapsed by partial voltage pulsing. We find that samples without an ohmic back contact show a slowly rising capacitance during the filling pulse. These samples show anomalous capacitance transients for short filling pulses.
Determination of the Density of States in a-SiC:H from Transient Photoconductivity
Authors: Brüggemann R. , Maint C. , Rösch M. , Webb D. P. 
Published: April 2011

AbstractIn order to fill the gap of little knowledge about their details, the density of states distributions (DOS) in the upper half of the band gap were determined for a series of wellcharacterised amorphous hydrogenated silicon carbide samples with Tauc gaps between 1.78 and 1.94 eV. A DOS spectroscopic technique, based on the Fourier transform of time-sampled transient photocurrents, allowed the DOS determination on an absolute scale for a wide energy range. The DOS increases in the band tail region with carbon content. It exhibits a minimum at about 0.5 eV which is followed by a defect structure at deeper energies, the density of which also increases with C-content. We find a decreasing time-dependent drift mobility for larger C-content consistent with the lower transit time-determined drift mobility in time-of-flight.
Comparison of Experiment and Theory of the Photoconductivity of a-Si:H up to a Generation Rate of 1028cm−3s−1
Authors: Stradins P. , Fritzschei H. , Tzanetakis P. , Kopidakis N. 
Published: April 2011

AbstractWe have studied the dependence of the photoconductivity σp on photocarrier generation rate G in intrinsic a-Si:H at 300K between G=1012cm−3s−1 and 1028cm−3s−1. Below a certain value Go, we find σo =AGγ with γ=0.9±0.05 and the values of A vary considerably with defect concentration Nd which signifies monomolecular recombination through defects. Above Go the recombination is bimolecular, γ=0.5±0.02 and A=(6±3)×10−15 Ω−1cm1/2s1/2 is indpendent of Nd. The transition value Go is about 3×1020cm−3s−1 for high quality annealed a-Si:H and increases with Nd. A simulation of σp(G) assuming conduction in and recombination from extended states fits our experiments within a capture coefficient Ct=(6±2)×10−9cm3s−1 of carriers to their opposite tail states. Our Ct is close to the value (5±2)×10−9cm3s−1 obtained from optical measurements but higher than (0.5±0.1)×10−9cm3s−1 determined from photoelectric studies. Below T=150K our model calculations overestimate σp because the tunneling transitions, becoming important for recombination and conduction, are neglected.