bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrical Properties of Diamond for Device Applications
Authors: Fox B. A. , Hartsell M. L. , Malta D. M. , Wynands H. A. , Tessmer G. J. , Dreifus D. L. 
Published: April 2011

ABSTRACTThe semiconducting properties of diamond make it a material of interest for the fabrication of active electronic devices. Device performance depends on the properties of the host diamond film and the device structure. Improvements in the electronic properties of chemical vapor deposited (CVD) diamond films and in device design are required for development of commercial diamond devices. Hall-effect and capacitance-voltage measurements have been used to assess the electronic quality of diamond films and to evaluate potential device materials and structures.
Homoepitaxial, highly oriented and polycrystalline CVD diamond films have been deposited and characterized by variable-temperature Hall-effect measurements. The highest room temperature hole mobility measured in a homoepitaxial film was 1590 cm2 /V•s where the compensation was ∼2 × 1015 cm-3. These properties are now beginning to approach those of the best type IIb natural diamonds. In a comparison of homoepitaxial, highly oriented diamond film, and polycrystalline diamond films, the room temperature hole mobility was 1470, 229 and 70 cm2/V•s, respectively. This data provides further evidence that the alignment of the grains improves the transport properties of diamond films.
Capacitance-voltage measurements have been performed on single crystal type lib diamond with metal-insulating diamond-semiconducting diamond and metal-oxi de-semiconducting diamond structures. Using a conductance versus frequency technique, the density of interface states was estimated to be ∼1012 cm-2eV-1 for both structures. Although optimization of these structures must still be performed, the ability to measure the interface trap density offers the opportunity to provide direct feedback to the device fabrication process so that the structure may be optimized.
Examples of Diamond Sensing Applications
Authors: Davidson J. L. , Kang W. P. 
Published: April 2011

ABSTRACTDiamond has attractive properties as an advanced electronic material. Its combination of high carrier mobility, electric breakdown, and thermal conductivity results in the largest calculated figures of merit for speed and power of any material. Recently, the discovery and development of what might be called sophisticated secondary effects in diamond, are opening interesting sensor applications. Boron doped diamond will change electrical resistance with strain (piezoresistance), meaning it can be used as a strain gauge on rugged electronic microsensors for pressure and acceleration sensing. This paper will present some critical issues of diamond for microelectromechanical sensing applications such as its rupture stress and edge stress of diamond diaphragms and the high temperature responses of a diamond pressure sensor. We will describe an all diamond pressure microsensor that measures pressure at more than 300°C. Also, we have observed that layered diamond films can behave as chemical sensors measuring hydrogen, oxygen and many other chemicals’ concentration. For example, a diamond-based chemical gas sensor using Pd/i-diamond/p+-diamond metal-insulator-semiconductor diode structure has been made and the behavior of a new diamond-based chemical gas sensor has been studied. Also, the creation and properties of diamond microtips as field emitters are discussed.
Diamond Sensors and Vacuummicroelectronics
Authors: Pan L. S. 
Published: April 2011

ABSTRACTThis paper will cover two diverse electronic applications for which diamond devices have shown great promise. The first application is diamond radiation sensors for high radiation environments, where the competition is mainly silicon devices. These environments arise in high energy physics experiments, and tests show diamond to be superior to silicon in many ways. The second application is vacuum microelectronics, which generally refers to field emission, where the main competitor is metal and semiconductor microtip arrays. Certain diamond and diamondlike carbon materials emit electrons readily, but the physical mechanisms for this are not well understood. Negative electron affinity and other possible explanations are discussed in this paper.
Characterization of Stress and Mosaicity in Homoepitaxial Diamond Films
Authors: Alexander W. Brock , Holloway Paul H. , Doering Patrick , Linares Robert 
Published: April 2011

ABSTRACTDiamond films were grown on (100) and (110) oriented natural diamond substrates by hot filament assisted chemical vapor deposition (HFCVD) to thicknesses of 7 to 100μm. Raman spectroscopy was used to measure tensile stresses of up to ∼2GPa for some of the (110) films. The development of stress was attributed to the incorporation of impurities (Re, Mo, and H). Impurity concentrations were greater at the interface than through the film thickness. Up to∼11% H and 50ppm Re were measured in the films with secondary ion mass spectrometry (SIMS). Homoepitaxial diamond films were further characterized using a seven crystal high resolution x-ray diffraction system. This new characterization tool allowed the separation of the effects of mosaicity from those of variation in lattice parameter.
Three-Phase Combustion Modelling: Frozen Ozone, a Prototype System
Authors: Miller Martin S. 
Published: April 2011

AbstractA number of efforts are currently underway in the U.S. to model the self-sustained combustion of solid energetic materials at the level of fundamental physical processes and elementary chemical reactions. Since many of these materials bum, at least at some pressures, with a liquid surface layer, these models must address phenomena in three physical phases. Most of these modeling efforts have focussed on pure RDX as a prototype. From a systems viewpoint this was a natural choice since it, or materials like it, is one of the components of modem propellants. It is argued here that, from a scientific viewpoint, RDX is already too complex with too many uncertain mechanisms and unavailable supporting data to serve this role effectively. We discuss here a number of issues related to the condensed phase and interfacial phenomena which have not been previously identified and which warrant more detailed research. In this paper frozen ozone is adopted as a more suitable prototypical 3-phase system. In this paper progress toward addressing this system is presented. The first new process to be modelled was a gas/surface reaction A detailed analysis was performed on the reaction mechanisms at play in the ozone flame and how they are affected by the heterogeneous reaction. Other new mechanisms are associated with the multicomponent nature of the liquid surface layer and will be addressed in future work.
Solid Propellant Flame Structure
Authors: Parr T. P. , Hanson-Parr D. M. 
Published: April 2011

AbstractPlanar Laser Induced Fluorescence (PLIF), UV/Vis Absorption, and thermocouple measurements were done for HNF, RDX, HMX, and XM39 deflagration with and without CO2 laser-support. RDX and especially HNF have very short self-deflagration flame length scales. HMX and XM39 have taller self-deflagration flames. XM39 has a marked dark zone with plateau temperature about 1400K. RDX's dark zone, present under laser supported deflagration, collapses when the external laser flux is removed. PLIF was used to measure the 2D NH, OH, and CN species profiles for these materials and OH temperature profile for RDX and HNF under non-laser supported conditions. The best spatial resolution for the RDX PLIF was about 4μm. Sandwiches of HNF and various binders were studied with PLIF and while obvious diffusion flames were present at low pressure, they are weak and are not expected to be burn rate controlling.
A Simplified Method for Determining Reactive rate Parameters for Reaction Ignition and Growth in Explosives
Authors: Miller Philip J. 
Published: April 2011

AbstractA simplified method for determining the reactive rate parameters for the ignition and growth model is presented. This simplified ignition and growth (SIG) method consists of only two adjustable parameters, the ignition (I) and growth (G) rate constants. The parameters are determined by iterating these variables in DYNA2D hydrocode simulations of the failure diameter and the gap test sensitivity until the experimental values are reproduced. Examples of four widely different explosives were evaluated using the SIG model. The observed embedded gauge stress-time profiles for these explosives are compared to those calculated by the SIG equation and the results are described.
Investigation of Shock-Induced Chemical Decomposition of Sensitized Nitromethane Through Time-Resolved Raman Spectroscopy
Authors: Pangilinan G. I. , Constantinou C. P. , Gruzdkov Y. A. , Gupta Y. M. 
Published: April 2011

AbstractMolecular processes associated with shock induced chemical decomposition of a mixture of nitromethane with ethylenediamine (0.1 wt%)are examined using time-resolved, Raman scattering. When shocked by stepwise loading to 14.2 GPa pressure, changes in the nitromethane vibrational modes and the spectral background characterize the onset of reaction. The CN stretch mode softens and disappears even as the NO2 and CH3 stretch modes, though modified, retain their identities. The shape and intensity of the spectral background also shows changes characteristic of reaction. Changes in the background, which are observed even at lower peak pressures of 11.4 GPa, are assigned to luminescence from reaction intermediates. The implications of these results to various molecular models of sensitization are discussed.
Detonation in Shocked Homogeneous High Explosives
Authors: Yoo C. S. , Holmes N. C. , Souers P. C. 
Published: April 2011

AbstractWe have studied shock-induced changes in homogeneous high explosives including nitromethane, tetranitromethane, and single crystals of pentaerythritol tetranitrate (PETN) by using fast time-resolved emission and Raman spectroscopy at a two-stage light-gas gun. The results reveal three distinct steps during which the homogeneous explosives chemically evolve to final detonation products. These are i) the initiation of shock compressed high explosives after an induction period, ii) thermal explosion of shock-compressed and/or reacting materials, and iii) a decay to a steady-state representing a transition to the detonation of uncompressed high explosives. Based on a gray-body approximation, we have obtained the CJ temperatures: 3800 K for nitromethane, 2950 K for tetranitromethane, and 4100 K for PETN. We compare the data with various thermochemical equilibrium calculations. In this paper we will also show a preliminary result of single-shot time-resolved Raman spectroscopy applied to shock-compressed nitromethane.
Detonation Synthesis of Nano-Size Materials
Authors: Forbes J. , Davis J. , Wong C. 
Published: April 2011

AbstractThe detonation of explosives typically creates 100's of kbar pressures and 1000's K temperatures. These pressures and temperatures last for only a fraction of a microsecond as the products expand. Nucleation and growth of crystalline materials can occur under these conditions. Recovery of these materials is difficult but can occur in some circumstances. This paper describes the detonation synthesis facility, recovery of nano-size diamond, and plans to synthesize other nano-size materials by modifying the chemical composition of explosive compounds. The characterization of nano-size diamonds by transmission electron microscopy and electron diffraction, X-ray diffraction and Raman spectroscopy will also be reported.
Metal/Metal Exothermic Reactions Induced by Low Velocity Impact*
Authors: Woody Diana L. , Davis Jeffery J. , Miller Philip J. 
Published: April 2011

AbstractThis paper discusses experimental results from an effort conducted to discern the basic mechanism of reactions in porous metal/metal compositions under rapid plastic flow conditions. Small-scale impact tests were performed on various intermetallic mixtures: 3CuO + 2AI, Fe2O3 + 2AI, Ni + Al, and 5Ti + 3Si. The addition of polytetrafluoroethylene (Teflon) to the metal/metal mixtures has been demonstrated to affect the extent of the reactions. Real-time emissivity and species evolution measurements of the reacting materials were used to discern the chemical reactions occurring under rapid plastic flow conditions.
Phase Relationships Involving RDX and Common Solid Propellant Binders
Authors: Boyer E. , Brown P. W. , Kuo K. K. 
Published: April 2011

AbstractThe solubilities of the common propellant ingredients acetyl triethyl citrate (ATEC) and cellulose acetate butyrate (CAB) and their effects on RDX (cyclotrimethylenetrinitramine) unit cell dimensions were investigated. If there is appreciable solid solubility, solutions will form and will have enthalpies of fusion, melting temperatures, and other characteristics different from those of pure RDX. It is desirable to establish the properties of such mixtures when designing new propellant formulations. Samples were aged at an elevated temperature to speed the formation of solid solutions. A least-squares analysis of X-ray diffraction data was used to obtain the lattice parameters from which unit cell volume and solubility was deduced. Both ATEC and CAB caused an expansion of the unit cell, indicating the formation of a solid solution. The limit of solubility in the ATEC/RDX mixture appeared to be approximately 13 wt% ATEC, while the CAB/RDX limit is above 16 wt% CAB. In both mixes, the cell volume expanded linearly with increasing proportion of binder.
Overview on Energetic Polymers
Authors: Boileau Jacques 
Published: April 2011

AbstractEnergetic materials for missiles, gun munitions or pyrotechnic devices often are mixtures in a biphasic form, with a filler and a binder. To satisfy the user needs, an analysis of functional requirements together with constraints (safety, vulnerability, ageing, environment, disposal, price...) is useful to choose a convenient binder. From this point of view numerous synthetic energetic polymers proposed or developed as binders are reviewed with regard to their syntheses, processing, properties and possible uses. These polymers contain explosophore groups: C-NO2aliphatic or aromatic, ONO2, NNO2, NF2and N3.Some research projects are suggested. Among them in the list of published polymers, following a NIMIC (NATO) suggestion, note the reason of a development interruption. Some dinitropolystyrene – polyvinyl nitrate mixtures or copolymers could exhibit interesting properties. For unknown reasons, some mixtures of crystalline filler- with polymeric binder, generally in a biphasic form, may also be monophasic for a same composition. What properties are modified between the both forms (e.g. combustion mechanisms, erosion, ideal character of the detonation) ? It is also interesting to pursue into a newly open route to thermo-plastic elastomers.
Characteristics of XeCl Excimer-Laser Annealed Insulator
Authors: Jang Keun-Ho , Choi Hong-Seok , Jun Jae-Hong , Yoo Jhun-Suk , Han Minkoo 
Published: April 2011

AbstractThe laser annealing effects on the TEOS (Tetra-Ethyl-Ortho-Silicate) oxide of MOS (AI/TEOS/n+ Silicon ) structures was investigated with different initial oxide conditions, such as breakdown field. The breakdown field increased upto the 170 mJ/cm2 with increasing laser energy density and decreased at 220 mJ/cm2. It is considered that the increase of breakdown field is originated from the restore of strains which exist mainly at the metal/oxide interface.
Hot-Wire Deposited Amorphous Silicon Thin-Film Transistors
Authors: Schropp R. E. I. , Feenstra K. F. , Werf C. H. M. Van Der , Holleman J. , Meiling H. 
Published: April 2011

AbstractWe present the first thin film transistors (TFTs) incorporating a low hydrogen content (5 - 9 at.-%) amorphous silicon (a-Si:H) layer deposited by the Hot-Wire Chemical Vapor Deposition (HWCVD) technique. This demonstrates the possibility of utilizing this material in devices. The deposition rate by Hot-Wire CVD is an order of magnitude higher than by Plasma Enhanced CVD. The switching ratio for TFTs based on HWCVD a-Si:H is better than 5 orders of magnitude. The field-effect mobility as determined from the saturation regime of the transfer characteristics is still quite poor. The interface with the gate dielectric needs further optimization. Current crowding effects, however, could be completely eliminated by a H2 plasma treatment of the HW-deposited intrinsic layer. In contrast to the PECVD reference device, the HWCVD device appears to be almost unsensitive to bias voltage stressing. This shows that HW-deposited material might be an approach to much more stable devices.
a-Si:H Photo Diode With Variable Spectral Sensitivity
Authors: Rieve Peter , Giehl Jürgen , Zhu Qi , Böhm Markus 
Published: April 2011

AbstractA novel two terminal thin film photo diode for color detection has been developed. The device structure which is based on standard amorphous silicon nipin multilayers exhibits three or even more linearly independent spectral sensitivity peaks and provides linearity over a wide range of illumination levels. Band gap engineering and electric field tailoring allow a precise voltage controlled shift of the collection region of photo generated carriers. The steady-state as well as the transient device characteristics have been studied in detail. Emphasis was put on optimization of the spectral sensitivity of the color diodes. Furthermore, an electronic color correction algorithm is presented which results in an improved color separation.
Optimized Three-Color Detector Based on a-SiGe:H Heterojunctions
Authors: Stiebig H. , Knipp D. , Fölsch J. , Finger F. , Wagner H. 
Published: April 2011

AbstractBandgap and μτ - (carrier mobility x lifetime) - engineered multi-color nipin detectors with three linear independent curves of the spectral response in a range from 470nm to 670nm are successfully fabricated. The spectral response of nipin structures employed as two terminal devices shifts by the applied voltage. Switching transients after changing the color sensitive voltages under different monochromatic illumination conditions are investigated and can be classified in different cases. In order to improve the understanding of the photo current transients, we have characterized the influence of different illumination conditions on the voltage dependent capacitance behavior. To verify the capacitance measurements, a SPICE model has been developed, which describes the transient behavior of the detector. The simulations are in good agreement with the experimental data and support the explanation of the transient cases after bias switching. Based on these results further optimization criteria to accelerate the transient behavior are presented.
Transient Behavior of Color Diodes
Authors: Giehl Jürgen , Zhu Qi , Rieve Peter , Böhm Markus 
Published: April 2011

AbstractAmorphous silicon (a-Si:H) based n-i-p-i-n/p-i-n-i-p structures serve as two color detectors. These basic structures can be extended to obtain multi color detection. In this paper capacitance measurements in the dark and under various illumination conditions as well as photo and bias current transient measurements in the time range 10-6-10-2 s are presented. The transients have been investigated for different bias voltages and photon fluxes.Device capacitance becomes strongly bias dependent if illumination is applied to the sensor. It is dominated by the reverse biased diode of the nipin/pinip structure. Bias and photocurrent transients are influenced by defect recharging due to injection. For high photon fluxes only defect states near the band edges contribute to the transient current. This behavior is confirmed by dispersion like transient phenomena. Under dark conditions deep defects influence the transient behavior.
A-Si:H Solar Cells Deposited Using VHF–PECVD
Authors: Sark W. G. J. H. M. Van , Bezemer J. , Heijden R. Van Der , Weg W. F. Van Der 
Published: April 2011

AbstractA-Si:H p+-i-n+ solar cells have been made employing plasma enhanced chemical vapour deposition at frequencies between 30–80 MHz. Here, only the i-layer was fabricated at these very high frequencies (VHF). Both the p+- and n+-layer were made using 13.56 MHz. A previous study has shown the material quality to depend on mainly the applied rf-power, and only slightly on the frequency. It should be noted that for homogeneity reasons a certain optimized pressure is required for each frequency. There is a clear correlation between material quality and solar cell parameters. An initial efficiency of 10 % has been obtained for cells deposited at 65 MHz using a low power density, while the deposition rate still is 2–3 times higher than the one at 13.56 MHz. Light-soaking reveals stabilisation at 6 % for the best cell, which compares well to conventional 13.56 MHz cells.
Effect Of μ-Doped Compensated Material on Stability of a-Si:H Solar Cells
Authors: Caputo D. , Cesare G. De , Palma F. , Tucci M. 
Published: April 2011

AbstractIn this paper we focus our attention on compensated materials with μ-doping concentration in order to obtain a stable intrinsic layer with initial high photoconductivity suitable for p-i-n solar cells. Films were grown from a mixture of undiluted silane, hydrogen diluted phosphine and hydrogen diluted diborane. Values of dark conductivity around 10-11 Ω-1cm-1 and photosensitivity ratio under AM 1.5 of 6 orders of magnitude have been obtained for phosphine/diborane ratio around 102. The difference between the two dopant concentrations is in agreement with the difference in doping efficiency of the two gases found in the characterization of single μ-doped films.We compared the degradation behavior of compensated and intrinsic materials with the same initial dark and light conductivity. After about 20 h the photoconductivity of the compensated and the intrinsic material decreased of 33% and 70%, respectively. The space of investigable deposition parameters has been limited by the stress induced by the simultaneous presence of phosphine and diborane which leads to a macroscopic, periodic and regular damage of the film.
Photoconductive Polycrystalline Silicon Films on Glass Obtained by Hot-Wire CVD
Authors: Middya A. R. , Guillet J. , Perrin J. , Bouree J. E. 
Published: April 2011

AbstractTextured polycrystalline silicon films with columnar structure have been deposited on glass at low temperature (400–550°C) and high deposition rate (10 to 15 Å/s) by hot-wire chemical vapour deposition using SiH4-H2 gases. The homogeneity of the deposited layer is ± 5% on a 8 cm diameter. As deposited films have a poor photoconductivity. However hydrogen confinement in the films during the deposition or after the deposition is found to be the key for obtaining g.tc/poly-Si with a significant diffusion length. Eventually reasonable values of the mobility lifetime product (> 10−7 cm2/V) are obtained by in situ hydrogen passivation of poly-Si films after deposition. Efficient shifting of the Fermi level is achieved by in situ B or P doping. The incorporation of boron in poly-Si network strongly influences the morphology and the crystalline structure. Undoped films have a Hall mobility of 14 ± 5 cm2/V.s which decreases versus the carrier concentration.