bluuebunny/crossref_metadata_2025_split huggingface dataset:
Defect Studies of the Transparent/Translucent Plastic Products Ujith the Polarized Light
Authors: Rahman Miftahur , Schott N. R. 
Published: March 2011

ABSTRACTThe applications of plastic products in the areas of medical science, computer technology and optics demand high quality and defect free products. The medical products such as implanted lenses to correct cataracts (opacity of the lens of the eye, causing partial or total blindness), contact lenses etc. need to be cmpletely defect free. The injection molded compact disc (CD) substrates of polycarbonate also require to be defect free as well as stress free. The retardation of the optical beam has to be less than 50 nm for single pass in the CD ROM and for erasable magneto-optical disk the retardation needs to be even lower in magnitude. Many optical components also require to be defect free and stress free. In this present investigation, a well known optical birefringence technique is used to study the stresses and microscopic defects such as foreign matter, voids, cracks, bubbles, inclusions, gels, etc. in these products using a commercially available polariscope.
Tunable Diode Laser Absorption Spectroscopy of the Pyrolysis of Methylsilazane
Authors: Sun H. C. , Bae Y. W. , Whittaker E. A. , Gallois B. 
Published: March 2011

AbstractAn understanding of the chemical processes occurring in the gas phase during metalorganic chemical vapor deposition is needed to design novel precursors and for the subsequent control of the composition and the microstructure of the solid product. Tunable diode laser absorption spectroscopy provides a means to precisely monitor specific bond rupture in the precursor during pyrolysis. Methylsilazane [CH3SiHNH]n,, a precursor to silicon-based ceramic thin films, was used to investigate the potential of this technique. Below the decomposition temperature, the intensity of the absorption line at 871.6±0.1 cm−1 corresponding to one of the harmonics from Si-CH3, increased linearly with the vapor pressure of methylsilazane up to 800 Pa and then decreased exponentially. The typical linewidths of the absorption line was approximately 0.006 cm−;1, orders of magnitude narrower than would be observable using conventional infrared techniques. The absorption line was detectable over a pressure range from less than 1 Pa to 10 kPa.
Laser Induced Fluorescence for Temperature Measurement in Reacting Flows
Authors: Joklik R. G. 
Published: March 2011

AbstractOH vibrational Thermally Assisted Fluorescence (THAF) temperature measurements have been demonstrated in both premixed and diffusion flames. The accuracy of the measurements is generally better than 100 K over a wide range of flame conditions for which the collisional quenching rate varies considerably. Application of this technique for temperature measurement in Chemical Vapor Deposition (CVD) flows, for which the quenching rate is relatively constant, should exhibit greater accuracy. THAF measurements in these flows are limited by signal to noise considerations, and should be possible down to pressures of 103-104 Pa or less.
In-Situ Optical Emission Spectra of Ti, TiN and TiSi2 Plasma During Thin Film Growth by Pulsed Laser Evaporation
Authors: Pramanick S. , Narayan J. 
Published: March 2011

AbstractThe first optical emission spectra of Ti, TiN and TiSi2 plasma during growth of thin films by pulsed laser evaporation has been reported. A KrF excimer laser (248nm) with pulsewidth of 45ns operating on 5Hz repitition rate was used for deposition of refractory metal thin films using varying laser fluence of 4J/cm2 to 15J/cm2. Most of the radiative species seen in plasma belongs to atomic neutrals and ionic species such as Ti I, Ti II, Si I, Si II and N 11. Emission spectra was mostly dominated by neutral and ionic emission from Titanium (Ti I and Ti II).
Near-Room Temperature Deposition of W and WO3 Thin Films by Hydrogen Atom Assisted Chemical Vapor Deposition
Authors: Lee Wei William , Reeves Robert R. 
Published: March 2011

AbstractA novel near-room temperature CVD process has been developed using H-atoms reaction with WF6 to produce tungsten and tungsten oxide films. The chemical, physical and electrical properties of these films were studied. Good adhesion and low resistivity of W films were measured. Conformal W03 films were obtained on columnar tungsten using a small amount of molecular oxygen in the gas stream. A reaction mechanism was evaluated on the basis of experimental results. The advantages of the method include deposition of adherent films in a plasma-free environment, near-room temperature, with a low level of impurity
Effect of Process Conditions and Chemical Composition on the Microstructure and Properties of Chemically Vapor Deposited SiC, Si, ZnSe, ZnS and ZnSxSe1-x
Authors: Pickering Michael A. , Taylor Raymond L. , Goela Jitendra S. , Desai Hemant D. 
Published: March 2011

AbstractSub-atmospheric pressure chemical vapor deposition (CVD) processes have been developed to produce theoretically dense, highly pure, void-free and large area bulk materials, SiC, Si, ZnSe, ZnS and ZnSxSe1-x. These materials are used for optical elements, such as mirrors, lenses and windows, over a wide spectral range from the vacuum ultraviolet (VUV) to the infrared (IR).In this paper we discuss the effect of CVD process conditions on the microstructure and properties of these materials, with emphasis on optical performance. In addition, we discuss the effect of chemical composition on the properties of the composite material ZnSxSe1-x.We first present a general overview of the bulk CVD process and the relationship between process conditions, such as temperature, pressure, reactant gas concentration and growth rate, and the microstructure, morphology and properties of CVD-grown materials. Then we discuss specific results for CVDgrown SiC, Si, ZnSe, ZnS and ZnSxSe1-x.
Effect of High Temperature Annealing on the Microstructure of SCS-6 SiC Fibers
Authors: Ning X. J. , Pirouz P. , Bhatt R. T. 
Published: March 2011

AbstractThe effect of annealing the SCS-6* SiC fiber for one hour at 2000°C in an argon atmosphere is reported. The SiC grains in the fiber coarsen appreciably and the intergranular carbon films segregate to the grain junctions. It would appear that grain growth in the outer part of the fiber is primarily responsible for the loss in fiber strength and improvement in fiber creep resistance.
Thin Film Properties of LPCVD TiN Barrier for Silicon Device Technology
Authors: Hegde Rama I. , Fiordalice Robert W. , Travis Edward O. , Tobin Philip J. 
Published: March 2011

AbstractThin film properties of LPCVD TiN barriers deposited on Si(100), using TiCl4 and NH3 as reactants, were investigated as a function of deposition temperature between 400 °C and 700 °C. The TiN film chemistry and film composition were studied by AES and RBS techniques, while the microstructural properties (grain size, lattice parameter and texture) were evaluated by XRD. The TiN deposition rates and film resistivities were also determined. Finally the film properties of the TiN barriers as determined by surface analysis were related to the process parameters.
Contribution of Gas-Phase Reactions to the Deposition of SiC by A Forced-Flow Chemical Vapor Infiltration Process
Authors: Tsai Ching-Yi , Desu Seshu B. 
Published: March 2011

AbstractA model, incorporating both gas-phase and surface reactions, for simulating thickness profile of SiC, deposited from trichloromethylsilane (TMS), along the longitudinal direction of a single pore is presented in this paper. The transport mechanisms considered include both forced-flow and diffusion. With the nonlinear nature of this model, a finite element model was developed to solve the problem numerically. Simulation results were in good agreement with the reported experimental data by Fedou et al. (1990). Effects of critical parameters, such as deposition temperature, ratio of sticking coefficients of TMS and intermediate species, and forced-flow, on the deposition thickness profile were investigated. Forced-flow effect was found to be small for the chemical vapor infiltration (CVI) processes at high deposition temperatures.
CVD of Silicon Carbide on Structural Fibers: Microstructure and Composition
Authors: Veitch Lisa C. , Terepka Francis M. , Gokoglu Suleyman A. 
Published: March 2011

AbstractStructural fibers are currently being considered as reinforcements for intermetallic and ceramic materials. Some of these fibers, however, are easily degraded in a high temperature oxidative environment. Therefore, coatings are needed to protect the fibers from environmental attack.Silicon carbide (SiC) was chemically vapor deposited (CVD) on Textron's SCS6 fibers. Fiber temperatures ranging from 1350 to 1500 °C were studied. Silane (SiH4) and propane (C3H8.) were used for the source gases and different concentrations of these source gases were studied. Deposition rates were determined for each group of fibers at different temperatures. Less variation in deposition rates were observed for the dilute source gas experiments than the concentrated source gas experiments. A careful analysis was performed on the stoichiometry of the CVD SiC-coating using electron microprobe. Microstructures for the different conditions were compared. At 1350°C, the microstructures were similar;however, at higher temperatures, the microstructure for the more concentrated source gas group were porous and columnar in comparison to the cross sections taken from the same area for the dilute source gas group.
The Oxidation Stability of Boron Nitride Thin Films on MgO and TiO2 Substrates
Authors: Qiu Xiaomei , Datye Abhaya K. , Paine Robert T. , Allard Lawrence. F. 
Published: March 2011

AbstractThe stability of BN thin film coatings (2–5 nm thick) on MgO and TiO2 substrates was investigated using transmission electron microscopy (TEM). The samples were heated in air for at least 16 hours at temperatures ranging from 773 K - 1273 K. On MgO supports, the BN thin film coating was lost by 1073 K due to a solid state reaction with the substrate leading to formation of Mg2B2O5. No such reaction occurred with the TiO2 substrate and the BN was stable even at 1273 K. However, the coating appeared to ball up and phase segregate into islands of near-graphitic BN and clumps of TiO2 (rutile). The oxidizing treatment appears to promote the transformation from turbostratic BN to graphitic BN.
Theoretical Study of Gas-Phase Thermodynamics Relevant to Silicon Carbide Chemical Vapor Deiposition
Authors: Allendorf Mark D. , Melius Carl F. 
Published: March 2011

AbstractEquilibrium calculations are reported for conditions typical of silicon carbide (SiC) deposition from mixtures of silane and hydrocarbons. Included are 34 molecules containing both silicon and carbon, allowing an assessment to be made of the importance of organosilicon species (and organosilicon radicals in particular) to the deposition process. The results are used to suggest strategies for improved operation of SiC CVD processes.
Chemical Vapor Deposition of Copper Oxide Thin Films
Authors: Chang Yuneng , Schrader Glenn L. 
Published: March 2011

AbstractCopper oxide films were prepared by organometallic chemical vapor deposition of copper acetylacetonate in an oxygen-rich environment. The films were characterized by X-ray diffraction, Auger electron spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. At 360 °C, Cu2O films were formed for an oxygen pressure of 150 torr and a copper acetylacetonate vapor pressure of 0.2 torr). The Cu2O film was polycrystalline, but the orientation was primarily [111]. Differential scanning calorimetry indicated that O2 assists decomposition of the organometallic precursor during pyrolysis.
Therirmochemistry in C.V.D. - on the Choice of Haliide Gas Species
Authors: Bernard C. , Madar R. 
Published: March 2011

AbstractThe production of thin or thick films of metals or ceramics by chemical vapour deposition has often been achieved by the use of halide gas precursors. In certain cases, this choice was made purely for reasons of simplicity: gas cylinder available, gas species already used in another field, etc. Experience has subsequently shown, however, that this choice can give rise to significant changes in the nature and proportions of deposited phases. These are highly dependent upon:
– the value of the oxidiser:reducer ratio in the gas phase,– the degree of metal oxidation in the halide considered,– possible competition between two reducing agents designed to reduce the halide.
These factors, among others, strongly influence the thermochemistry of the deposition reaction. Their roles must therefore be clearly understood, interpreted and predicted by the thermochemical analysis. Based on examples relating to silicide, nitride and boride deposits, an attempt will be made to determine the sensitive parameters and to deduce selection criteria.
Deposition of Tungsten Nitride thin Films from (tBuN)2w(NHtBu)2
Authors: Chiu Hsin-Tien , Chuang Shiow-Huey 
Published: March 2011

AbstractThe possibility of growing tungsten nitride thin films from (tBuN)2W(NHtBu)2, a single-source molecular precursor with two nitrogen to tungsten double bonds, by low pressure chemical vapor deposition (LPCVD) was investigated. Deposition of thin films on silicon and glass substrates was carried out at temperatures 500 – 650 °C in a cold-wall reactor while the precursor was vaporized at 60 – 100 °C. Elemental composition of the thin films, studied by wavelength dispersive spectroscopy (WDS), is best described as WNx (x = 0.8 – 1.8). Elemental distribution within the films, studied by Auger depth profiling, is uniform. X-ray diffraction (XRD) studies show that the films have a cubic structure with a lattice parameter a = 4.14 – 4.18 Å. A stoichiometric WN thin film has a lattice parameter a equal to 4.154 Å. Volatile products, trapped at −196°C, were analyzed by nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry (GC-MS). Isobutylene, acetonitrile, hydrogen cyanide and ammonia were detected in the condensable mixtures.
Diamond Deposition by a Nonequilibrium Plasma Jet
Authors: Keil D. G. , Calcote H. F. , Felder W. 
Published: March 2011

AbstractA nonequilibrium plasma jet has been used to deposit diamond films on a number of substrates, including silicon, silicon nitride, alumina, and molybdenum. Hydrogen is passed through a glow discharge and expanded through a supersonic nozzle to produce a highly nonequilibrium jet. Methane is added downstream of the nozzle, where it mixes and reacts with the nonequilibrium concentration of hydrogen atoms. The resulting supersonic jet strikes the substrate surface producing a high quality (determined by laser Raman spectrometry) adherent diamond film. Because of the low jet temperature, substrate cooling is unnecessary. Diamond deposition rates have exceeded 2 mg/kWh and I μm/h averaged over 16 cm2 area; good quality films prepared at substrate temperatures below 600 K. have been
Onset Conditions for Gas Phase Reaction and Nucleation in the CVD of Transition Metal Oxides
Authors: Collins J. , Rosner D. E. , Castillo J. 
Published: March 2011

AbstractA combined experimental/theoretical study is presented of the onset conditions for gas phase reaction and particle nucleation in hot substrate/cold gas CVD of transition metal oxides. Homogeneous reaction onset conditions are predicted using a simple high activation energy reacting gas film theory. Experimental tests of the basic theory are underway using an axisymmetric impinging jet CVD reactor. No “vapor phase ignition” has yet been observed in the TiCl4/O2 system under accessible operating conditions (below substrate temperature Tw=1700 K) and further experiments are planned using more reactive feed materials. The goal of this research is to provide CVD reactor design and operation guidelines for achieving acceptable deposit microstructures at the maximum deposition rate while simultaneously avoiding homogeneous reaction/nucleation and diffusional limitations.
Step Coverage Modeling of Thin Films Deposited by CVD Using Finite Element Method
Authors: Tsai Ching-Yi , Desu Seshu B. 
Published: March 2011

AbstractA two—dimensional finite element model was developed to study the step coverage of submicron trenches with arbitrary shape under chemical vapor deposition processes. Parameters that characterize the step coverage were found to be the surface Damkohler number, ratio of diffusion coefficients inside and outside of the trench, and aspect ratio of the trench geometry. Efforts were concentrated on studying the step coverage of SiO2 film deposited from SiH4/O2 precursors within rectangular shape trenches. The model predictions were found to be in good agreement with reported experimental results.
Surface Chemistry of Fluorine-Containing Molecules Related to CVD Process on Silicon Nitride: SiF4, XeF2, and HF
Authors: Outka Duane A. 
Published: March 2011

AbstractThe reactivity of several fluorine-containing molecules on a polycrystalline silicon nitride (Si3N4) surface is studied under ultrahigh vacuum (UHV) conditions using temperature programmed desorption (TPD) and Auger electron spectroscopy (AES). The chemistry of fluorine on Si3N4 is of interest in understanding the high temperature chemical vapor deposition (CVD) of Si3N4, which uses SiF4 as a starting material. XeF2 is reacted with a Si3N4 surface to prepare and characterize various surface SiFx (1 ≤ × ≤ 3) species. These are identified by the chemical shift induced by the fluorine atoms in the Si (LMM) Auger peak and by changes in the TPD. Of these species, SiF2 is stable to the highest temperature. SiF2 is also formed by the reaction of SiF4 with a Si3N4. Because SiF2 is so stable, its decomposition is proposed as a rate-determining step in the CVD deposition of Si3N4 from SiF4. Gaseous HF, which is a product of the CVD process, does not dissociate on Si3N4 and is therefore unlikely to cause the etch-like marks on the Si3N4 coating that are observed under certain conditions.
In-Situ Light-Scattering Measurements During the CVD of Polycrystalline Silicon Carbide
Authors: Sheldon Brian W. , Reichle Philip A. , Besmann Theodore M. 
Published: March 2011

AbstractLight-scattering was used to monitor the chemical vapor deposition of silicon carbide from methyltrichlorosilane. The nucleation and growth of the SiC features caused changes in the surface topography that altered the angular scattering spectrum that was generated with a He-Ne laser. These scattering spectra were then analyzed to obtain information about the nucleation and growth processes that are occurring.
Impurity Gettering in Silicon by Thin Polycrystalline Films
Authors: Hayamizu Y. , Ushio S. , Takenaka T. 
Published: March 2011

ABSTRACTCapability of impurity gettering by thin polycrystalline films on the backside of silicon wafer was evaluated by minority-carrier diffusion length. Cu was gettered easily during usual cooling after high temperature annealing. On the other hand, intentional slow cooling or low temperature annealing was necessary for effective Fe gettering. The gettering efficiency for Fe increased with lowering the annealing temperature when Fe was diffused sufficiently. From the quantitative consideration of Fe gettering, we propose the model of impurity gettering based on the chemical equilibrium of impurity reaction in polysilicon films. It was also expected that gettering efficiency increased with the thickness of polysilicon film.
Defects Introduced by Plasma Processing of Silicon
Authors: Benton J. L. 
Published: March 2011

ABSTRACTThe electrical and optical properties of defects introduced by Reactive Ion Etching (RIE) in the near surface region of Si after dry etching with various gases and plasma conditions is studied with spreading Resistance (SR), photoluminescence (PL), and capacitance-voltage profiling (C-V). Plasma etching in chlorine and fluorine based gases produce donors at the surface in both n-type and p-type, Czochralski and float-zone silicon. Isochronal annealing reveals the presence of two distinct regions of dopant compensation. The surface damage region is confined to 1000 Å and survives heat treatment at 400°C, while the defect reaction region extends ≥ 1 μm in depth and recovers by 250°C. A comprehensive picture of the interstitial defect reactions in RIE silicon is completed. The interstitial defects, Ci and Bi, created in the ion damaged near surface region, undergo recombination enhanced diffusion caused by the presence of ultraviolet light in the plasma, resulting in the long range diffusion into the Si bulk. Subsequently, the interstitial atoms are trapped by the background impurities forming the defect pairs, CiOi, CSCi, or BiOi, which are observed experimentally. The depth of the diffusion-limited trapping and the probability of forming specific pairs depends on the relative concentrations of the reactants, oxygen, carbon or boron, present in the bulk material.
Defect Formation by Ion Implantation in Cz-Si Studied by a Monoenergetic Positron Beam
Authors: Uedono A. , Ujihira Y. , Wei L. , Tabuki Y. , Tanigawa S. , Sugiura J. , Ogasawara M. , Tamura M. 
Published: March 2011

ABSTRACTVacancy-type defects in ion implanted Si were studied by a monoenergetic positron beam. The depth-distributions of the defects were obtained from measurements of Doppler broadening profiles of the positron annihilation as a function of incident positron energy. The results showed that a size of vacany-clusters introduced by 150-keV P+-ion implantation was found to be smaller than that introduced by 2-MeV P+-ion implantation. This was attributed to an overlap of collision cascades in low-energy (150 keV) ion implanted specimens. From isochronal annealing experiments for 80-keV B+- and 150-keV P+-ion implanted specimens, the defected region was removed by 1200 °C annealing, however, for 2-MeV P+-implanted specimen, two-types of oxygen-vacancy complexes were found to coexist even after 1200 °C annealing.
Generation of Defects and Strain by Ion Implantation in Ge (100) Single Crystals, and in Pseudomorphic GexSi1-x Films Grown on Si (100)
Authors: Lie D. Y. C. , Vantomme A. , Eisen F. , Nicolet M. -A. , Arbet-Engels V. , Wang K.L. 
Published: March 2011

ABSTRACTWe have studied the damage and strain produced in Ge (100) single crystals by implantation of various doses of 300 keV 28Si ions at room temperature. The analyzing tools were x-ray double-crystal diffractometry, and MeV 4He channeling spectrometry. The damage induced by implantation produces positive strain in Ge (100). The maximum perpendicular strain and maximum defect concentration rise nonlinearly with increasing dose. These quantities are linearly related with a dose-independent coefficient of ∼ 0.013 for Ge (100) single crystals implanted at room temperature. The results are compared with those available for Si (100) self-implantation. We have also monitored the strain and defects generated in pseudomorphic Ge0.1Si0.9/Si (100) films induced by room temperature 28Si ion implantation. It is found that the relationship between the strain and defect concentration induced by ion implantation is no longer a simple linear one.
Dopant Dependent Extended Defect Nucleation and Growth Kinetics in Silicon During 1 Mev Electron Irradiation
Authors: Romano-Rodriguez Albert , Vanhellemont Jan 
Published: March 2011

ABSTRACTIn this paper results of a study of electron irradiation induced extended defect generation in doped silicon is presented. The irradiations are performed in-situ with 1 MeV electrons in a high voltage transmission electron microscope. Preferential generation of extended defects is observed in certain areas of the sample which can be correlated with well defined dopant concentration levels. The defect growth kinetics is studied as a function of the irradiation temperature and dose and the type and concentration of dopant.After the first irradiation experiment some of the samples received a second electron irradiation, during which shrinkage and even complete annihilation of the previously generated defects can be observed. The observed results are interpreted on the base of point defect reactions.