bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optical Switches Based on Vanadium Dioxide Films Grown By The Sol-Gel Process
Authors: Potember Richard S. , Speck Kenneth R. 
Published: March 2011

ABSTRACTVanadium dioxide thin films have been grown from vanadium tetrakis (t-butoxide) by the sol-gel process. A new method for the synthesis of the vanadium precursor was also developed. Films were deposited by dipcoating glass slides from an isopropanol solution, followed by post-deposition annealing of the films at 600°C under nitrogen. The properties of these films, to a high degree, were a function of crystalline boundaries and crystalline grain size. These gel-derived VO2 films undergo a reversible semiconductor-to-metal phase transition near 72°C, exhibiting characteristic resistive and spectral switching comparable with near stoichiometric VO2 films prepared on non-crystalline substrates by other techniques. Films were doped with hexavalent transition metal oxides to demonstrate lowering of the transition of the transition temperature.
Preparation of Phenylsiloxane Films VIA Solution Deposition Techniques
Authors: Burkhardt E.W. , Burford R.R. , Deatcher J.H. 
Published: March 2011

ABSTRACTThin films (1–10μ thick) can be spin coated on a variety of substrates from formulations containing polyphenylsiloxanes and alkylsilicates. These films may be cured either thermally or photochemically, yielding films with good adherence to the substrate. The combination of photolysis and thermolysis results in changes in the film hardness characteristics. The use of a mask during photocuring results in films which may be developed in either a positive or negative fashion. The preparation of various formulations along with film curing processes will be discussed.
Polymerizations of Alkenylsilanes Using Early Transition Metal Catalysts
Authors: Masnovi John , Bu Xin Y. , Conroy Paula , Harry Andrist A. , Hurwitz Frances I. , Miller Doug 
Published: March 2011

ABSTRACTOxidative coupling of primary alkylsilanes catalyzed by Group IVB metallocene complexes leads predominantly to linear polysilanes, as first reported by Harrod. We have investigated the polymerization of ethylsilane and vinylsilane using dimethyltitanocene in order to determine the suitability of such polymers as precursors to Si-C based ceramics for application as coatings or composite matrices. A photochemical procedure for initiation of polymerization is described. Ethylsilane forms polysilanes (which contain a -Si-Si-Si-Si- backbone) by a step growth mechanism. Vinylsilane shows some Si-Si formation; however, polymerization by several different routes, including formation of polycarbosilanes (which contain a -Si-C-SI-C- backbone) by hydrosilation reactions and crosslinking via metathesis, predominate. The carbosilane polymer has high char yield (60-75%) and appears advantageous for conversion into silicon carbide, as determined by X-ray diffraction.
The use of Soluble Metal-Polyselenide Complexes as Precursors to Binary and Ternary Solid Metal Selenides
Authors: Dhingra S. , Kanatzidis M. G. 
Published: March 2011

ABSTRACTThe use of several soluble metal polychalcogenides to prepare solid state materials is presented. Thermal gravimetric analysis (TGA) data, under inert atmosphere, of the molecular compounds (Ph4P)2[Cd(Se4)2], (Ph4P)4[Cu2Se14], (Ph4P)2[Cu4Se12], (Ph4P)4[In2Se21] and (Et4N)3[M3Se15], (M=In, TI), show that the corresponding binary solid state compounds are formed as single phases at temperatures as low as 530°C. We have grown films of CdSe, Cu2-xSe, β-In2Se3, TISe and CuInSe2 using these complexes as precursors. The films were prepared by pyrolysis of green precursor films, cast from DMF solutions. CuInSe2 was prepared by co-thermolysis of Cu/Sex and In/Sex complexes. The chemical, X-ray, spectroscopic and electron microscopic characterization of these molecular precursor-derived films as well as their charge transport characterization is reported.
Plasma Synthesis of Fine Ceramic Powders by a Novel Counter-Flow Liquid Injection Method.
Authors: Kong P. , Or T.W. , Stachowicz L. , Pfender E. 
Published: March 2011

ABSTRACTCeramic powders of carbides, oxides, solid solutions of oxides, magnetic and non-magnetic spinels, superconductors and composites have been successfully synthesized in a thermal plasma jet reactor using a novel counter-flow liquid injection plasma synthesis (CF LIPS) method developed to overcome the problems associated with solid injection and to realize the benefits of gas phase reactions and counter-flow injection. Standard material characterization techniques have been used for powder analysis.
Superconducting Fibers from Anhydrous Metal Carboxylates
Authors: Laine Richard M. , Youngdahl Kay A. , Kennish Richard A. , Hoppe Martin L. , Zhang Zhi-Fan , Jean Ray D. 
Published: March 2011

ABSTRACTA variety of anhydrous Y, Ba and Cu carboxylates were synthesized and screened for utility as spinnable precursors to 123 superconducting fibers. Simple extrusion studies demonstrate that THF solutions of mixtures of Y, Ba and Cu isobutyrates with some Ba 2-ethyl- hexanoate can be used to form 70 μm dia. precursor fibers. Following a curing at 150°C for 24–48 h, pyrolysis of these fibers in air to 900°C, with controlled heating rates, gives dense, flexible ceramic fibers 15–20 μm in dia. These fibers have the appropriate orthorhombic phase. Flux exclusion measurements indicate the fibers are superconducting; but ΔTc is not optimal.
Polyfunctional Carboxylic Acids as Coprecipitating Agents For Barium, Yttrium, and Copper
Authors: Hallock Robert B. , Rexer P.O. , Jolly M.S. , Rhine W.E. , Cima M.J. 
Published: March 2011

ABSTRACTThe suitability of several polyfunctional carboxylic acids as coprecipitating agents for Ba, Y, and Cu was investigated. Essentially complete precipitation from alcoholic solutions was achieved for all three metals when tartaric acid was employed as the precipitating agent. The amorphous precipitate formed under these conditions was composed of uniform particles about 50 nm in diameter, and was converted readily to high purity Ba2YCu3O7−x.
Ten Minute Preparation Of Yba2Cu3O7−x Using Barium Hydroxide
Authors: Coppa N. , Kebede A. , Schwegler J. W. , Perez I. , Salomon R. E. , Myer G. H. , Crow J. E. 
Published: March 2011

ABSTRACTHigh quality bulk YBa2CuOx−7 was synthesized by fusing stoichiometric amounts of yttrium and copper nitrates and barium hydroxide, in air, using an ordinary Bunsen burner. The starting materials go through a short-lived liquid phase yielding a solid black product which was subsequently heat treated, (900 C, 18–24 h, in air, followed by 500 C, 5 h., in O2). These materials were greater than 99% phase pure with CuO as the only other phase and they exhibited a transition temperature of 92 K, a 15.5% perfect diamagnetic response (field cooled), 76% (zero field cooled). This synthesis represents an improvement over the much more labor and time intensive conventional methods in that it allows high quality materials of various compositions to be prepared quickly
Rubbery Ormosils
Authors: Chung Young J. , Ting Su-Jen , Mackenzie John D. 
Published: March 2011

ABSTRACTA new technique which permits the successful preparation of ORMOSILS (Organically Modified Silicates) with rubbery elasticity has been developed. Common alkoxides were reacted with polydimethyl siloxane (PDMS) and the microstructures were carefully controlled. Large monoliths of the porous rubbery ORMOSILS have been prepared. Gelation process was studied by 29Si liquid NMR spectroscopy. A structural model for rubber elasticity of ORMOSILS was proposed.
Applications of Solid Phase Doping in Manufacturing MOS Devices
Authors: Gong S. F. , Hentzell H. T. G. , Robertsson A. 
Published: March 2011

AbstractSolid phase doping from Sb heavily-doped Si films has been studied by using transmission electron microscopy and secondary ion mass spectroscopy. Based on the results of the material study, metal-oxidesemiconductor field effect transistors (MOSFETs) made on a (100) Si wafer, and thin film transistors have been implemented. The technique for the MOSFETs suggests the possibility for making small dimensional and high speed integrated circuits by using the method of solid phase doping.
Effect of Grain Boundary Segregation on the Transbarrier Conductivity of Polycrystalline Silicon
Authors: Pizzini S. , Acciarri M. 
Published: March 2011

AbstractThe conductivity of single grain boundaries of electronic grade, Bridgman grown polycrystalline silicon samples was measured using the dc polarization technique with the aim of detecting any influence on the carrier transport regime resulting from the segregation of oxygen and carbon, which, by themselves, should behave as electrically inactive impurities. To this scope as grown samples and samples heat treated at 1123 and 1223 K, differing in their initial oxygen and carbon content, were used and the conductivity measured in the 298-100 K range.The results indicate that for both the carbon rich and for the oxygen rich samples the conductivity across the grain boundaries is of the thermally activated type and that it could be discussed in terms of carriers which are thermally emitted over the barrier and cross the barrier in the limit of the short mean free path.Samples which do not present a net excess of oxygen or carbon, apparently behave as single crystal specimens, instead.The deconvolution of the I-V curves is then used for obtaining the densitl of the interface states responsible of the set-up of the grain boundaries barrier, whose shape supports a completely new hypothesis about the configuration of the impurity cloud at the grain boundaries.
In Situ Hrem Observations of Crystallization in LPCVD Amorphous Silicon
Authors: Morgiel J. , Wu I.W. , Chiang A. , Sinclair R. 
Published: March 2011

AbstractThis article describes the application of in situ, high-resolution electron microscopy to the study of crystal nucleation and growth in amorphous silicon. It is shown that dynamic events at elevated temperatures (e.g. 600-750°C) can be recorded at the atomic level by such an approach. It is anticipated that fundamental information, important for the technological development of polysilicon thin films, can be generated by work of this type.
Characterization of Polycrystalline Silicon Thin Films by Photoluminescence
Authors: Pandya R. , Shahzad K. 
Published: March 2011

AbstractPhotoluminescence (PL) measurements have been carried out in hydrogenated and as deposited polycrystalline silicon thin films deposited on quartz substrates. Behavior of the PL spectrum as a function of temperature and intensity in the hydrogenated samples is reported. A mechanism that provides a qualitative explanation for the observed PL results is described. In the unhydrogenated sample the signal was much weaker and we were unable to observe any signals over an appreciable range of intensity and temperatures. The cause for much lower signals in the unhydrogenated sample is most likely due to higher surface recombination velocity.
Electrical and Structural Characterization of Polysilicon Deposited in a Rapid Thermal Processor
Authors: Ren X. , Öztüirk M.C. , Wortman J.J. , Batchelor D. , Maher D. , Blat C. , Niccolian E. 
Published: March 2011

AbstractLow pressure chemical vapor deposition of polysilicon in a lamp heated rapid thermal processor (RTCVD) has been studied. Polysilicon films were deposited using SiH4 diluted in Ar. Structural characterization of the films was accomplished by transmissionelectron microscopy (TEM), scanning tunneling microscopy (STM), secondary ion mass spectroscopy (SIMS), auger electron spectroscopy (AES) and ultraviolet surface reflectance measurements. Smooth polysilicon films were obtained at deposition temperatures above 700ºC with rms roughness values better than 100 Å. Both p- and n- polysilicon gated MOS capacitors were fabricated using 80 - 200 Å thick gate oxides grown by dry oxidation in a conventional furnace. Polysilicon doping was achieved by ion-implantation and rapid thermal annealing (RTA). Our results show that the electrical properties ofthe capacitors fabricated using RTCVD polysilicon are comparable to those of conventional polysilicon. Dopant diffusion through the gate is a problem for both types of polysilicon and can lead to a degradation of the electrical properties.
Polysilicon Thin Film Transistors
Authors: Yudasaka Ichio , Ohshima Hiroyuki 
Published: March 2011

AbstractPolysilicon thin film transistors are now in mass production. Key factors of the success are thinner polysilicon film and thermal oxidation. Practical applications of polysilicon thin film transistors have been limited, however, because of high temperature processing. Alternative technologies to thermal oxidation are very low pressure deposition, solid-phase crystallization, laser-annealing and hydrogenation. These technologies are compatible with low temperature processing and will contribute to the advance of polysilicon thin film transistors in the future.
Measurements of Grain Boundary Trap Density and Hydrogen Diffusivity in Polycrystalline Silicon Fet's
Authors: Moore Chad B. , Ast Dieter G. 
Published: March 2011

AbstractHydrogen diffusion in as-deposited and in oxidation-annealed polycrystalline silicon films was investigated using n-type accumulation-mode MOSFET's. The diffusion was studied by measuring the reduction in the grain boundary trap density with hydrogenation time. The number of traps in fully hydrogenated as-deposited films fell to about 45% of the initial trap state density and fell to about 20% in the oxidized-annealed films. Concurrently, the mobility increased about 95 % to 5cm2/Vs in the as-deposited films and by about 55 % to 25 cm2/Vs in the oxidized polysilicon devices. The effective preexponential diffusion coefficient and activation energy for hydrogen diffusion in the two different films were Do= 5.4×10−10 cm2/s and EA= 0.37 eV for the as-deposited polysilicon and Do=2.1×10−10 cm2/s and EA= 0.36 eV for the oxidized polysilicon.
Effect of Gate Dielectric on Performance of Polysilicon thin Film Transistors
Authors: Hatalis Miltiadis K. , Kung Ji-Ho , Kanicki Jerzy , Bright Arthur A. 
Published: March 2011

AbstractThe effect of gate dielectric on the electrical characteristics of n-channel polysilicon thin film transistors was investigated. The following insulators were studied: silicon dioxide grown by wet oxidation, silicon dioxide deposited by plasma enhanced chemical vapor deposition (PECVD) and nitrogen-rich silicon nitride deposited by PECVD. It was observed that the effective electron mobility in TFTs having a deposited dielectric, either silicon nitride or silicon dioxide was higher than that measured in devices with grown silicon dioxide. The TFT leakage current was found to be lowest in devices with PECVD silicon nitride. Devices with deposited dielectrics did not degrade after a positive gate bias stress. However, reduction of the threshold voltage was observed in devices with PECVD silicon nitride, when they were subjected to a negative gate bias stress.
Properties of in Situ Doped Polycrystalline Silicon Films Deposited from Phosphine and Disilane
Authors: Madsen Lynnetie D. , Weaver Louise 
Published: March 2011

AbstractThe deposition of in situ phosphorus doped silicon films was performed using disilane (Si2H6) instead of monosilane (SiH4) as the silicon source gas. The negative aspects of in situ doping with phosphine, namely low deposition rates and poor across wafer uniformity, were to a large extent eliminated. Haze-free polycrystalline films were deposited at ∼60 Å-min1 with less than 5% radial thickness variation over a 100 mm wafer. However, the temperature suitable for depositing films using Si2H6 was shifted downward from that used for SiH4 and similarly, the conditions for good quality (haze-free)films were adjusted. Within specific temperature ranges, varying the gas pressure, flow,and Si2H6 to PH3 ratio resulted in the formation of oneof three types of haze. The films produced had unusually low resistivities of ∼770 μohm-cm after furnace annealing at 850ºC for 1800s. A 20 nm thick surface layer of amorphous silicon oxide was revealed during transmission electron microscopy (TEM) examination of annealed films. Although this oxide layer was undoped, the phosphorus gradient, measured by energy dispersive x-ray analysis (EDX) and secondary ion mass spectroscopy (SIMS), increased towards the surface of the polycrystalline film, suggesting that dopant was diffusing to the surface. A matrix involving different annealing and capping layers was conducted to investigate this phenomenon further. Extremely large grains resulted when a capping layer of SiO2 was deposited prior to rapid thermalannealing (RTA). An autodoping effect was observed when another capping layer, such as undoped polycrystalline silicon, was used.
Thermal Stability of CoSi2 on Single Crystal and Polycrystalline Silicon
Authors: Phillips J. R. , Revesz P. , Olowolafe J. O. , Mayer J. W. 
Published: March 2011

AbstractThe thermal stability of Co silicide on single crystal and polycrystalline Si has been investigated. Co films were evaporated onto (100) Si and undoped polycrystalline Si and annealed in vacuum. Resulting silicide films were examined using Rutherford backscattering spectroscopy, scanning electron microscopy, electron—induced x—ray spectroscopy, and sheet resistivity measurements. We find that CoSi2 on single crystal (100) Si remains stable through 1000ºC. In contact with undoped polycrystalline Si, intermixing begins at temperatures as low as 650ºC for 30min annealing. The Co silicide and Si layers are intermixed after 750ºC 30min annealing, giving islands of Si surrounded by silicide material, with both components extending from the surface down to the underlying oxide layer. The behavior of CoSi2 contrasts with results reported for TiSi2 which agglomerates on single crystal Si around 900ºC but is stable on polycrystalline silicon as high as 800ºC. Resistivity measurements show that the Co silicide remained interconnected despite massive incursion by Si into the silicide layer.
Cobalt Silicide Formation on Polysilicon: Dopant Effects on Reaction Kinetics and Silicide Properties
Authors: Sitaram A.R. , Murarka S.P. 
Published: March 2011

AbstractThe concept of using cobalt disilicide as a self-aligned metallization scheme for gate/interconnection and contact formation is gaining wide acceptance. The silicide formation on the gate will require a Co-metal film interaction with the underlying polysilicon that may be doped heavily. We have investigated the silicide formation kinetics during this reaction. The effect of different dopants (B,P, and As) and their concentration on the Co-Si interaction and the dopant redistribution during such reactions were investigated. The results from these studies will be presented and discussed.
Microanalysis of Tungsten Silicide/Polysilicon Interface: Effectiveness of in Situ Rie Clean on Removal of Native Oxide
Authors: Nowicki Ronald S. , Geraghty Patrice , Harris David W. , Lux Gayle 
Published: March 2011

AbstractThe presence of a thin (10-30Å) oxide (“native oxide”) layer on a silicon surface prior to the deposition of another film on that surface can contribute todifficulties with subsequent device processing steps, e.g. contact metallization and hightemperature annealing or oxidation. Thus, the in situ process capability of “native oxide” removal affords an advantage over the conventional method of aqueous hydrofluoric acid cleaning prior to a film deposition step. This study describes such a technique, in which an in situ pre-deposition clean with C2F6 gas, using reactive ion etching (RIE) prior to tungsten silicide deposition, is employed. This technique allows post-silicide deposition high-temperature heat treatment and wet oxidation without loss of film adhesion or other obvious degradative effects. We also report the useof Secondary Ion Mass Spectrometry (SIMS) to show that this procedure has een effective in the removal of the oxide layer prior to silicide deposition. This study includes definition of the RIE etch parameters which provide acceptable etch selectivity of the oxideto silicon, and avoidance of excessive fluoropolymer formation on the silicon surface.
Rapid Thermal Annealed TIW/TI Contact Metallization for Advanced VLSI Si Circuits
Authors: Chung Henry W. , Yao Agnes T. 
Published: March 2011

AbstractRapid thermal annealed (RTA) bilayers of TiW/Ti were evaluated for contact metallization in advanced VLSI Si circuits. It was found that RTA and a minimum thickness of Ti are necessary to achieve consistently low + contact resistance. RTA has little effect on n+ and polysilicon contact resistances. With RTA, TiSi2 is formed at the Ti/Si interface and a thin nitrogen—containing layer is formed on the TiW surface. By controlling RTA temperature and time, the interaction between Si and TiW during RTA could be minimized while the gain factor of p—channel MOSFETs was not degraded. Moreover, the leakage currents of n+ and p+ contact chains did not increase after 30 minute anneals up to 525C.
Hrem of Defects in Silicon at Twin Intersections
Authors: Hetherington C. J. D. 
Published: March 2011

AbstractDefects found in and around intersections of deformation twins have been examined by high resolution electron microscopy. Experimental difficulties, especially local buckling of the crystal and radiation damage under the electron beam, lead to a need to interpret images of lattices tilted by almost a degree from the zone axis. This paper demonstrates the ability of image simulation programs to model successfully the scattering from a tilted crystal. It is shown how the generation of moir6 patterns between a lattice image and a reference array of dots offers a convenient method for extracting information about distortions of the lattice around defects.
Misfit Dislocations at II-VI/GaAs Interfaces
Authors: Schwartzman A. F. 
Published: March 2011

AbstractHigh-resolution electron microscopy -is used to characterize the defect structure of CdTe/GaAs and ZnTe/GaAs heterojunctions before and after annealing. For as-deposited films, a variety of defects exist both in the form of perfect misfit dislocations at the interface and extended defects into the thin film. The extended defects result from dissociation of 60° dislocations and reactions between perfect and partial dislocations lying on intersecting slip planes. The annealed interfaces consist of a periodic array of perfect edge Lomer dislocations, the most efficient type of misfit dislocation for accomodating the lattice mismatch, 14.6 % for CdTe/GaAs and 8 % for ZnTe/GaAs. In both cases, the spacing between dislocations corresponds to the value predicted for completely strain-free thin fims, 31 and 54 Å for CdTe and ZnTe respectively. This paper concentrates on the different dislocation reactions which transform the interfacial structure from the as-deposited case to the annealed case.