bluuebunny/crossref_metadata_2025_split huggingface dataset:
SiC Power Devices
Authors: Chow T. P. , Ghezzo M. 
Published: April 2011

AbstractThe present status of SiC high-voltage power switching devices is reviewed. The figures of merits that have been used for unipolar and bipolar devices to quantify the intrinsic performance improvement over silicon are presented. Analytical and numerical modeling and simulations to estimate the BV and device choice are described. The active area and termination design of trenched-gate MOS power transistors, together with an integrated process for their fabrication, is presented. The progress in high-voltage power device experimental demonstration is described. The material and process technology issues that need to be addressed for SiC device commercialization are discussed. Finally, the impact of SiC power devices on motor drive systems is estimated.
Low Temperature Growth of Nanocrystalline Silicon From SiF4 + SiH4
Authors: Chen Yu , Taguchi M. , Wagner S. 
Published: April 2011

AbstractThe electrical conductivity of nc-Si films grown from SiF4 and H2 with constant arsenic doping rises from 10-5 to 10 Scm-1 as the thickness rises from ˜ 0.1 to 1 μm. This variation demonstrates the strong influence of film structure on conductivity. We show that the conductivity of undoped nc-Si films of constant thickness can be varied by adding SiH4 to the SiF4 and H2 source gas.
Hydrogen Behavior in PECVD Nitride by SiH4 & ND3 During RTA
Authors: He S. S. , Shannon V. L. , Nguyen T. 
Published: April 2011

AbstractPECVD silicon nitride was deposited by silane and deuterium ammonia. Silicon rich and nitrogen rich silicon nitride were deposited by varying the ratio of the SiH4/DH3. From FTIR, we found that the wave numbers of SiD and ND shifted lower when compared to SiH and NH bond in the NH3 nitride. In Si-rich nitride, both Si-H and Si-D bonds were found, which is different from N-rich nitride, where only an ND bond was found. Most of the hydrogen in NH(D) comes from the ammonia during PECVD deposition. We found that some of the deuterium exchanges its bonding to silicon from the initial bonding to nitrogen during a rapid thermal annealing process.
Ac and Dc Characterization and Spice Modeling of Short Channel Polysilicon Tfts
Authors: Jacunski M. D. , Shur M. S. , Ytterdal T. , Owusu A. A. , Hack M. 
Published: April 2011

AbstractWe present an analytical SPICE model for the AC and DC characteristics of n and p channel polysilicon TFTs which scales fully with channel length and width in all regimes of operation (leakage, subthreshold, above threshold, and kink) and accounts for the frequency dispersion of the capacitance. Once physically based parameters have been extracted from long channel TFTs, which include the gate length and drain bias dependencies of the device parameters, our model accurately reproduces short channel device characteristics. The AC model includes the input channel resistance in series with the gate oxide capacitance. As a result, our model is able to fit the frequency dispersion of the device capacitances. The model has been implemented in the AIM-Spice simulator and good agreement is observed between measured and modeled results for gate lengths down to 4 gim.
Copper-Enhanced Solid Phase Crystallization of Amorphous Silicon Films
Authors: Sohn Dong Kyun , Moon Dae Gyu , Ahn Byung Tae 
Published: April 2011

AbstractLow-temperature crystallization of amorphous Si (a-Si) films was investigated by adsorbing copper ions on the surface of the films. The copper ions were adsorbed by spincoating of Cu solution. This new process lowered the crystallization temperature and reduced crystallization time of a-Si films. For 1000 ppm solution, the a-Si film was partly crystallized down to 500°C in 20 h and almost completely crystallized at 530°C in 20 h. The adsorbed Cu on the surface acted as a seed of crystalline and caused fractal growth. The fractal size was varied from 10 to 200 prm, depending on the Cu concentration in solution. But the grain size of the films was about 400 nm, which was similar to that of intrinsic films crystallized at 600°C.
Comparison Between Rapid Thermal and Furnace Annealing for A-Si Solid Phase Crystallization
Authors: Kingi Reece , Wang Yaozu , Fonash Stephen J. , Awadelkarim Osama , Mehlhaff John 
Published: April 2011

AbstractRapid thermal annealing and furnace annealing for the solid phase crystallization of amorphous silicon thin films deposited using PECVD from argon diluted silane have been compared. Results reveal that the crystallization time, the growth time, and the transient time are temperature activated, and that the resulting polycrystalline silicon grain size is inversely proportional to the annealing temperature, for both furnace annealing and rapid thermal annealing. In addition, rapid thermal annealing was found to result in a lower transient time, a lower growth time, a lower crystallization time, and smaller grain sizes than furnace annealing, for a given annealing temperature. Interestingly, the transient time, growth time, and crystallization time activation energies are much lower for rapid thermal annealing, compared to furnace annealing.We propose two models to explain the observed differences between rapid thermal annealing and furnace annealing.
Polycrystalline Silicon Films Formed by Solid-Phase Crystallization of Amorphous Silicon: the Substrate Effects on Crystallization Kinetics and Mechanism
Authors: Song Y.-H. , Kang S.-Y. , Cho K. I. , Yoo H. J. , Kim J. H. , Lee J. Y. 
Published: April 2011

AbstractThe substrate effects on the solid-phase crystallization of amorphous silicon (a-Si) have been extensively investigated. The a-Si films were prepared on two kinds of substrates, a thermally oxidized Si wafer (SiO2/Si) and a quartz, by low-pressure chemical vapor deposition (LPCVD) using Si2H6 gas at 470 °C and annealed at 600 °C in an N2 ambient for crystallization. The analysis using XRD and Raman scattering shows that crystalline nuclei are faster formed on the SiO2/Si than on the quartz, and the time needed for the complete crystallization of a-Si films on the SiO2/Si is greatly reduced to 8 h from ˜15 h on the quartz. In this study, it was first observed that crystallization in the a-Si deposited on the SiO2/Si starts from the interface between the a-Si film and the thermal oxide of the substrate, called interface-induced crystallization, while random nucleation process dominates on the quartz. The very smooth surface of the SiO2/Si substrate is responsible for the observed interface-induced crystallization of a-Si films.
TMCTS for gate dielectric in thin film transistors
Authors: Wang Albert W. , Bhat Navakanta , Saraswat Krishna C. 
Published: April 2011

AbstractThe use of the liquid source tetramethylcyclotetrasiloxane (TMCTS) for gate dielectric deposition in low-temperature polysilicon thin film transistor (TFT) processes is investigated. TMCTS was reacted with O2 in an LPCVD furnace at 580°C to form a gate dielectric. For comparison, a low temperature oxide (LTO) was deposited as a gate dielectric using SiH4−O2 LPCVD at 450°C. Capacitance and charge pumping measurements indicate fewer interface states for TMCTS gate dielectric. Both NMOS and PMOS TFTs show comparable or superior performance with TMCTS oxide. Post-deposition annealing has less effect on TMCTS gate oxides. Although TMCTS gate dielectrics appear slightly more susceptible to damage in biastemperature stress tests, TFTs with TMCTS gate oxides still retain better performance after stressing.
Liquid-crystals for multimedia display use: materials and their physical properties
Authors: Naemura S. 
Published: April 2011

AbstractDisplay devices are one of the key elements of the coming multimedia infrastructure, and Thin-Film-Transistor addressed Liquid Crystal displays are most promising for this application. Physical properties such as dielectric permitivities and electric resistivity are essentially important for TFT-addressing use LC materials. Both theoretical and experimental studies on these properties are reviewed and discussions are made on these in relation to the chemical structure of the liquid crystal substances, providing semiquantitative explanations on the superiority of fluorinated LC materials in respect to the coexistence of the high polarity and the high resistivity. Further studies to improve LC material properties are finally suggested.
Suspended particle display using novel complexes
Authors: Takeuchi H. , Usuki A. , Tatsuda N. , Tanaka H. , Okada A. , Tojima K. 
Published: April 2011

AbstractSuspended particle display (SPD) can be controlled in transparency by applying a.c. voltage. We found new synthesized particles for SPD and methods for making them fine. Three new SPD particles showing different colors have been found: δ-herapathite, 1,10-phenanthroline-iodine complex and pyrazinophenanthroline-iodine complex as showing red, blue, purple, respectively. Recrystallization and ultrasonic treatment were found to make them fine crystals. Accordingly, transparency, stability for sedimentation and thermal stability were improved.
Effect Of Base Pressure In Sputter Deposition On Characteristics Of Indium Tin Oxide Thin Film
Authors: Lee Byung Hak , Yi Choong-Hoon , Kim Lee Gon , Lee Si-Hyun 
Published: April 2011

AbstractA novel approach to sputter deposit low resistivity indium tin oxide thin films in cost effective way has been made. To reduce the complication of out-gassing from organic substances that are deposited at prior process steps in the flat panel display manufacturing, DC+RF magnetron sputtering was performed with a relatively high base pressure. Introduction of impurity atoms originated from residual air in the chamber into the film produced the change in lattice as well as microstructure of the film. Sputter deposition with higher base pressure resulted in lower resistivity of the film. Increase in the mobility of the carrier resulted in resistivity decrease. Resistivity as low as 1.5×10−4 Ω cm has been achieved with DC 0.67 W/cm2 + RF 0.67 W/cm2 power density and 10−5 Torr base pressure. X-ray diffraction analysis showed as much as 0.2 % increase in lattice constant resulted from higher base pressure sputtering. No further improvement of conductivity was observed for the base pressure over 10−5 Torr, suggesting impurity introduction saturation into the film.
Gold Overcoatings on Spindt-Type Field Emitter Arrays
Authors: Skala S. L. , Ohlberg D. A. , Talin A. A. , Felter T. E. 
Published: April 2011

ABSTRACTThe electron emission properties of a Spindt-type field emitter array have been measured before and after deposition of approximately 100 Å of gold. The workfunction of the emitter decreased by 5% after gold deposition resulting in an 11% reduction in turn-on voltage. Emission stability as measured by RMS current noise improved by 40%. Improvements in emission do not withstand exposure to air. However, baking at moderate temperatures (200°C) restores the emission improvements obtained with the gold overcoating. Fowler-Nordheim plots show that the enhanced emission after baking is due to a increase of the Fowler-Nordheim intercept and not a decrease in slope. Additionally, the gold over coatings resist poisoning as a 50,000 L dose of oxygen only slightly affects emission.
High-Rate Deposited Amorphous Silicon Nitride for the Hydrogenated Amorphous Silicon Thin-Film Transistor Structures
Authors: Li Tong , Chen Chun-Ying , Malone Charles T. , Kanicki Jerzy 
Published: April 2011

AbstractHydrogenated amorphous silicon nitride thin films, prepared in a large area plasma-enhanced chemical vapor (PECVD) deposition system utilizing high-rate deposition technique, have been characterized by various techniques. Experimental data obtained from this study are presented and compared to low-rate deposited PECVD films. Special attention has been devoted during this study to the difference between high- and low-rate deposited samples. The amorphous silicon (a-Si:H) thin-film transistors (TFTs) based on high-rate PECVD materials have been fabricated and characterized. The evaluation of a-Si:H TFTs indicates a good electrical performance which is comparable to its low-rate PECVD materials counterparts.
Variation of Luminescent Efficiency With Size of Doped Nanocrystalline Y203:Tb Phosphor
Authors: Goldburt E. T. , Kulkarni B. , Bhargava R. N. , Taylor J. , Libera M. 
Published: April 2011

ABSTRACTIn doped nanocrystalline Y203:Tb phosphors the luminescent efficiency was found to increase with the decrease in the particle size from 100 Å to 40 Å. This correlation was obtained from microstructural studies performed using transmission electron microscopy and luminescent measurements.
TiO2:Ce/CeO2 High Performance Insulators For Thin Film Electroluminescent Devices
Authors: Bally A. R. , Prasad K. , Sanjinés R. , Schmid P. E. , Lévy F. , Benoit J. , Barthou C. , Benalloul P. 
Published: April 2011

AbstractThe electrical properties of titanium dioxide thin films have been stabilised by cerium doping. These films have a high permittivity between 35 to 45 and withstand 650°C. Multilayer TiO2:Ce/CeO2 insulators have been fabricated. The breakdown voltage is increased by a factor 10 with a modest decrease in the permittivity (30 – 35 instead of 35 – 45).Electroluminescent devices (ELDs) with a classical ZnS:Mn phosphor have been prepared using TiO2:Ce as the first insulator and a TiO2:Ce/CeO2 multilayer as the second insulator. Compared with a standard ELD based on Y2O3 insulators, devices with the new insulators show a significant decrease of the threshold voltage along with a notable increase of the brightness. An important increase is also achieved in the total device efficiency which is maintained over a large range of brightness and transferred charge. Consequences of rapid thermal annealing and conventional thermal treatments on device performance have also been investigated.
Silicon Nanoclusters In Silica: A Luminescence Study Of Visible Light Emission From A Siliconbased Material
Authors: Trwoga P. F. , Kenyon A. J. , Pitt C. W. 
Published: April 2011

AbstractConsiderable interest has been generated recently in the application of Porous Silicon to the production of light emitting devices, and a number of demonstration structures have been produced. However, the poor stability of the material pose limitations on its usefulness. We report studies of the luminescence properties of a related, but stable material: silicon-rich silica. This material consists of silicon clusters embedded in a host matrix of silica, and as such is considerably more robust than porous silicon.We have produced a number of samples of silicon-rich silica thin films by Plasma Enhanced Chemical Vapour Deposition on to doped silicon substrates. We report photoluminescence studies that investigate the nature of the radiative process, and show evidence of two separate luminescence mechanisms: defect luminescence and exciton confinement in nanoscale silicon clusters. Preliminary electroluminescence from silicon-rich silica fabricated by Plasma Enhanced Chemical Vapour Deposition will also be presented.
Amorphous Silicon TFTs on Steel-Foil Substrates
Authors: Theiss S. D. , Wagner S. 
Published: April 2011

AbstractWe describe the successful fabrication of device-quality a-Si:H thin-film transistors (TFTs) on stainless-steel foil substrates. These TFTs demonstrate that transistor circuits can be made on a flexible, non-breakable substrate. Such circuits could be used in reflective or emissive displays, and in other applications that require rugged macroelectronic circuits.Two inverted TFT structures have been made, using 200 gim thick stainless steel foils with polished surfaces. In the first structure we used the substrate as the gate and utilized a homemade mask set with very large feature sizes: L = 45 μm; W = 2.5 mm. The second, inverted staggered, structure used a 9500 Å a-SiNx:H passivating/insulating layer deposited on the steel to enable the use of isolated gates. For this structure we used a mask set which is composed of TFTs with much smaller feature sizes. Both TFT structures exhibit transistor action. Current-voltage characterization of the TFTs with the inverted staggered structure shows typical on/off current ratios of 107, leakage currents on the order of 10-12A, good linear and saturation current behavior, and channel mobilities of 0.5 cm2/V·sec. These characteristics clearly identify the TFTs grown on stainless steel foil as being of device quality.
Vitrification and Morphological Stability of Liquid Crystals
Authors: Mastrangelo J. C. , Chen S. H. , Blanton T. N. , Bashir-Hashemi- A. 
Published: April 2011

AbstractBased on the extensive database collected for model glass-forming liquid crystals with various mesogenic groups attached to benzene, cubane, cis- and trans-cyclohexane, and all-exobicyclo[ 2.2.2]oct-7-ene, it was found that the glass-forming ability and morphological stability are determined by a delicate structural balance between the volume-excluding core and the pendant group, and the stereochemical features of the hybrid system.
Photorefractivity and Holographic Storage Effect in Fullerene C60-Doped Nematic Liquid Crystals
Authors: Khoo I. C. , Wood M. V. , Guenther Brett D. 
Published: April 2011

Abstract:The results of a recent study of a nonlinear electro-optical effect in fullerene C60-doped nematic liquid crystal film are presented. In particular, photo-induced conduction, self diffraction effect, and permanent holographic formation in the films are explained.
Model Systems for Liquid Crystal Based Dispersed Heterogeneous Materials
Authors: Aliev F. M. , Sinha G. P. 
Published: April 2011

AbstractPorous matrices with determined pore size, volume fraction and structure can be used as model systems to understand physical properties of dispersed liquid crystals (LC) - material important for different applications. Using photon correlation spectroscopy and dielectric spectroscopy we investigated dynamic properties of nematic liquid crystal dispersed in porous matrices with randomly oriented, interconnected pores (porous glasses with average pore sizes of 100 Å and 1000 Å) and parallel cylindrical pores (Anopore membranes with pore diameters of 200 Å and 2000 Å). Since the structural characteristics of these matrices are nearly independent of the temperature, all observable effects due to temperature changes can be attributed to the change in the physical properties of the second component (bC). The spatial confinement and a highly developed interface in porous matrices have a strong influence on the optical and dielectric properties of confined LC which is resulted in: appearance of at least two new dielectrically active modes, absent in the bulk and existence of slow glass-like relaxational process detected in both dielectric and photon correlation experiments.
Synthesis of Thin Films by Polymerization of Liquid Crystalline Monomers
Authors: Kurihara S. , Iwamoto K. , Nonaka T. 
Published: April 2011

AbstractMixtures of mono- and diacrylates showing a nematic phase were polymerized in an electric field. The orientation of chromophores in the thin films depended on the direction of dipole moment as well as the polymerization conversion of the liquid crystalline monomers.
Inhibition of Metal Induced Crystallization in the System Ag/ZnO/a-Si:H
Authors: Edelman F. , Brener R. , Cytermann C. , Weil R. , Beneking C. , Beyer W. 
Published: April 2011

AbstractA systematic investigation has been made on the barrier properties of ZnO layer between ndoped a-Si:H and Ag metallization films in the structures (001)Si/SiO2/Ag/ZnO/a-Si:H:P and (001)Si/SiO2/a-Si:H:P/ZnO/Ag. Plasma assisted CVD deposition was used to produce a-Si:H (2500Å thick) highly P-doped films over thermally oxidized Si-wafers at 190 and 270°C. Transparent conductive ZnO:AI layers, 1000Å and lμm thickness, and Ag films (1000Å thick) were deposited by sputtering. The polycrystalline ZnO layers were textured along the <0001> axis in the as-deposited state. The structures were annealed in vacuum in the temperature range from 300 to 700°C for 1/4 to 16h. X-ray diffraction and transmission electron microscopy studies demonstrated the a-Si:H:P stability against crystallization under ZnO buffer protection up to 700°C (when free a-Si crystallizes itself). The (111) peak position of the Ag reflection was used to show that while the Ag was always strained, the strain was partially relaxed when in contact with the 0. 1μm ZnO film, it developed additional strain when in contact with the 1μm ZnO film.
The Performance of Cu(In, Ga)Se2-Based Solar Cells in Conventional and Concentrator Applications
Authors: Tuttle J. R. , Ward J. S. , Duda A. , Berens T. A. , Contreras M. A. , Ramanathan K. R. , Tennant A. L. , Keane J. , Cole E. D. , Emery K. , Noufi R. 
Published: April 2011

AbstractCu(In, Ga)Se2 (CIGS) solar cells are under investigation for 1-sun and concentrator applications. Design criteria are examined and reveal that only grid design modifications are required. In the special case where cell width dimensions are 4–5 cm, an interdigitated design removes the back contact as a loss mechanism. Processing issues relating to the intrinsic ZnO layer are critical to optimal and reproducible cell performance. 1-sun and 20 sun performance of 17.7% are reported for different cells. The latter represents a 2.9% absolute improvement over the 1-sun control measurement. 20% performance is therefore a realistic goal. CIGS-based cells represent a viable concentrator technology.
Advanced Stacked Elemental Layer Process for Cu(InGa)Se2 Thin Film Photovoltaic Devices
Authors: Probst V. , Karg F. , Rimmasch J. , Riedl W. , Stetter W. , Harms H. , Eibl O. 
Published: April 2011

AbstractTargeting large area and low cost processing of highly efficient thin film solar modules an advanced stacked elemental layer process for Cu(InGa)Se2 (CIGS) thin films is presented. Key process steps are i) barrier coating of the soda lime glass substrate combined with the addition of a sodium compound to the elemental Cu/In/Ga/Se-precursor stack and ii) rapid thermal processing (RTP) to form the CIGS compound.By this strategy exact impurity control is achieved and the advantageous influence of sodium on device performance and on CIGS film formation is demonstrated unambiguously by means of electrical characterisation, XRD, SEM, TEM and SIMS. Sodium enriched and sodium free precursor stacks were heated to intermediate states (300°C–500°C) of the RTPreaction process. The experiment clearly reveals that on the reaction pathway to the chalcopyrite semiconductor increased amounts of copper-selenide are formed, if sodium is added to the precursor films. TEM-electron diffraction unambiguously identifies the CuSe-phase which is localised at the surface of the forming CIGS-film. These experimental findings propose a sodium assisted quasi liquid growth model for the CIS formation taking into account that sodium promotes the existence of CuSe at higher temperatures and its effect as a flux agent. The model contributes to a better understanding of the observed superior crystal qualitiy for sodium enriched in contrast to sodium free CIGS films.Application of these experimental findings in the technique of the optimized and controlled sodium incorporation significantly improves process reproducibility, CIGS film homogenity over larger substrate areas and shifts the average efficiency of cells and modules to a significantly higher level. This is demonstrated by a 12-cell integrated series connected minimodule with an aperture area of 51 cm2 and a confirmed efficiency of 11.75 %.