bluuebunny/crossref_metadata_2025_split huggingface dataset:
Silicon Nucleation on Silicon Dioxide and Selective Epitaxy In An Ultra-High Vacuum Raptid Thermal Chemical Vapor Deposition Reactor Using Disilane In Hydrogen
Authors: Violette Katherine E. , Sanganeria Mahesh K. , Öztürk Mehmet C. , Harris Gari , Maher Dennis M. 
Published: March 2011

AbstractSilicon nucleation on silicon dioxide and selective silicon epitaxial growth (SEG) were studied in an ultra high vacuum rapid thermal chemical vapor deposition (UHV-RTCVD) reactor. Experiments were performed using 10% Si2H6 in H2 in a pressure range of 10 - 100 mTorr at 760°C. Under these conditions, the growth rate ranged from 75 to 330 nm/minute. Loss of selectivity via Si island formation on SiO2 was studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealing a strong dependence on deposition pressure. Cross sectional transmission electron microscopy (XTEM) was employed to study the vertical oxide/epitaxy interface where faceting can occur. The incubation time for nucleation was found to increase from 10s to 70s as pressure is reduced from 100 mTorr to 10 mTorr, allowing thicker selective epitaxial film growth in spite of the reduced growth rates. This was attributed to the reduction in gas phase supersaturation of the Si containing species resulting in a lower density of adsorbed atoms on the SiO2 surface. This process shows a potential for chlorine free selective epitaxial growth and provides insight to the surface morphology of polycrystalline films deposited at low pressures.
Mombe Growth of Ybco Superconducting Films With In-Situ Monitoring of Rheed Oscillations
Authors: Endo K. , Teherani F. Hosseini , Yoshida S. , Kajimura K. , Moriyasu Y. 
Published: March 2011

AbstractWe have succeeded in in-situ growth of YBCO superconducting films by developing a new MOMBE technique which employs in-situ monitoring of RHEED intensity. The X-ray diffraction pattern showed peaks corresponding to those calculated from the Laue function which indicates the high quality of films grown using MOMBE. AFM and RHEED oscillations show 2-dimensional unit cell by unit cell growth.
Room Temperature Fabrication of Micro-Crystalline Silicon Films for Tft's By Ecr Pecvd
Authors: Jeon Yoo-Chan , Lee Seok-Woon , Joo Seung-Ki 
Published: March 2011

AbstractMicrocrystalline silicon films were formed at room temperature without hydrogen dilution by ECR PECVD. Microwave power more than 400 W was necessary to get crystalline films and the crystallinity increased with the power thereafter. Addition of hydrogen and argon enhanced the crystalline phase formation and the deposition rate, the reason of which was found that hydrogen etched silicon films and argon addition drastically increased the etch rate. Annealing of the films showed that microcrystalline silicon films formed by ECR PECVD have a small fraction of amorphous phase. TFT's using silicon nitride and doped/undoped microcrystalline silicon films were fabricatedd with whole processes at room temperature.
MOCVD Growth of Epitaxial SrTiO3 Thin Films on YBa2 Cu3O7−x/LaAlO3
Authors: Liang S. , Chern C. , Shi Z. Q. , Lu Y. , Lu P. , Kear B. H. , Safari A. 
Published: March 2011

AbstractStrontium titanate (SrTiO3) thin films have been epitaxially grown on YB2Cu3O7−x (YBCO)/LaAlO3 at substrate temperatures of 660 to 700°C. X-ray diffraction (XRD) results indicated that single crystalline SrTiO3 thin films were epitaxially grown on the substrate with <100> orientation perpendicular to the substrates. The compositions of the films with different growth conditions were examined by Rutherford backscattering spectroscopy (RBS) and energy dispersive x-ray spectroscopy (EDX). The ratio of Sr/Ti is in the range of 0.9 to 1.1 for the films with a thickness of 1000–2000Å. The surface morphology of the films and the interfaces of the SrTiO3/YBCO structure were examined by scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). Very smooth surface and sharp interface were observed. The superconducting property of the YBCO layer, as measured by ac susceptibility, did not degrade after growth of SrTiO3 film. The dielectric constant as high as 320 was obtained at 100KHz. The leakage current density is less than 1×10−6A/cm2 at 3V operation.
Deposition of Titanium Oxide Films from Metal-Organic Precursor by Electron Cyclotron Resonance Plasma-Assisted Chemical Vapor Deposition
Authors: Nagahori Atsushi , Raj Rishi 
Published: March 2011

AbstractTitanium oxide thin films were deposited at room temperature by the Electron Cyclotron Resonance Plasma-Assisted Chemical Vapor Deposition (ECR-PACVD) method. Effects of deposition temperature, microwave power and plasma gas pressure were investigated. Both Ar and O2 plasma were used to deposit films from titanium isopropoxide (Ti(OC3H7)4) precursor. Transparent titanium oxide films were obtained with O2 plasma. Refractive index and thickness were measured by ellipsometry and the films were characterized by x-ray diffraction.
Heteroepitaxial Si-ZrO2-Si by MOCVD
Authors: Greenwald Anton C. , Kalkhoran Nader M. , Namavar Fereydoon , Kaloyeros Alain E. , Stathakos Ioannis 
Published: March 2011

AbstractThe objective of this research was to demonstrate heteroepitaxial growth of yttria stabilized cubic zirconia on single crystal silicon substrates by chemical vapor deposition (CVD) using metalorganic source materials. We succeeded in depositing extremely smooth, well aligned films of zirconia on silicon substrates, both the <100> and <111> orientations, without an oxide interfacial layer. Experimental variables investigated included varying zirconia source materials, substrate temperatures, oxygen concentration, gas flow rates, yttria doping, substrate orientation, and cobalt-silicide as an oxygen diffusion barrier. ZrO2 films were predominantly tetragonal when deposited in the absence of oxygen while cubic phase material could be put down at 750°C with oxygen background. Films deposited from TMHD zirconium contained no measurable carbon contamination. Deposits from trifluoro-acetylacetonate Zr contained small amounts of fluorine, even in the presence of water vapor, and some carbon when hydrogen was used as a diluent gas.
Numerical Analysis of an Impinging Jet Reactor for the CVD and Gas-Phase Nucleation of Titania
Authors: Gokoglu Suleyman A. , Stewart G. D. , Collins J. , Rosner D. E. 
Published: March 2011

AbstractWe model a cold-wall atmospheric pressure impinging jet reactor to study the CVD and gas-phase nucleation of TiO2 from a titanium tetra-iso-propoxide (TTIP)/oxygen dilute source gas mixture in nitrogen. The mathematical model uses the computational code FIDAP and complements our recent asymptotic theory for high activation energy gas-phase reactions in thin chemically reacting sublayers. The numerical predictions highlight deviations from ideality in various regions inside the experimental reactor. Model predictions of deposition rates and the onset of gas-phase nucleation compare favorably with experiments. Although variable property effects on deposition rates are not significant (∼11% at 1000K), the reduction of rates due to Soret transport is substantial (∼75% at 1000K).
High Quality YBaCuO Thin Film Growth by Low-Temperature Metalorganic Chemical Vapor Deposition Using Nitrous Oxide
Authors: Zama Hideaki , Saga Jun , Hattor Takeo , Oda Shunri 
Published: March 2011

AbstractLow-temperature growth of YBa2Cu3Ox films by metalorganic chemical vapor deposition using N2O as an oxidizing agent has been investigated. We have deposited superconducting YBa2Cu3Ox on (100)MgO substrates at 500°C for the first time. Films of 15nm-thick show zero-resistivity critical temperature of 80K. Films of as thin as three unit-cell-thick reveal the superconducting onset characteristics. This result suggests that superconductivity is arisen even from effectively monomolecular layer of YBa2Cu3Ox when we take into account monomolecular buffer layer and monomolecular cap layer. YBa2Cu3Ox films of 9nm-thick grown on (100)SrTiO3 at 600°C with Tc(zero) of 79K and with peak to valley roughness fluctuation of two unit-cell have been obtained.
Plasma Enhanced Metal-Organic Chemical Vapor Deposition of Germanium Nitride Thin Films
Authors: Hoffman David M. , Rangarajan Sri Prakash , Athavale Satish D. , Economou Demetre J. , Liu Jia-Rui , Zheng Zongshuang , Chu Wei-Kan 
Published: March 2011

AbstractAmorphous germanium nitride thin films are prepared by plasma enhanced chemical vapor deposition from tetrakis(dimethylamido)germanium, Ge(NMe2)4, and an ammonia plasma at substrate temperatures as low as 190°C with growth rates >250 Å/min. N/Ge ratios in the films are 1.3 and the hydrogen contents are 13 atom %. The hydrogen is present primarily as N-H. The refractive indexes are close to the bulk value of 2.1, and the band gap, estimated from transmission spectra, is 4.8 eV.
Atomic Layer Controlled Deposition of Al2O3 Films Employing Trimethylaluminum (TMA) and H2O Vapor
Authors: Dillon A. C. , Ott A. W. , George S. M. , Way J. D. 
Published: March 2011

AbstractSequential surface chemical reactions for the controlled deposition of Al2O3 films were studied using transmission Fourier transform infrared spectroscopy (FTIR). Experiments were performed in situ in an ultrahigh vacuum UHV chamber using high surface area alumina membranes. Trimethylaluminum [Al(CH3)3] (TMA) and H2O vapor were employed sequentially in an ABAB... binary fashion to achieve atomic layer controlled growth. An optimal Al2O3 growth procedure was established that employed TMA/H2O exposures at .3 Torr and 500 K. The experiments revealed that each reaction was self-terminating and atomic layer controlled growth was dictated by the surface chemistry. The controlled deposition of Al2O3 may be employed on silicon surfaces for the formation of high dielectric gate and passivation layers.
Group 2 Element Chemistry and its Role in OMVPE of Electronic Ceramics
Authors: Rees William S. 
Published: March 2011

AbstractCoordination compounds of alkaline-earth metals with simple monodentate ligands were mentioned in the literature as early as 1820, when Faraday reported ‘metal-ammonias’.[1] The number of heavy alkaline earth element coordination compounds remained limited for many years, however, as it was thought to be unlikely for the large earth alkaline cations to form such complexes. In 1967 Pedersen discovered that cyclic oligoethers (crown ethers) can serve as suitable ligands for divalent alkaline earth cations.[2] His findings were extended a few years later by Lehn who found that macrobicyclic multidentate ligands (cryptands) are efficient ligands for alkaline earth cations.[3] In each of these examples, the primary mode of metal-ligand interaction is electrostatic in origin. These examples demonstrate the lack of well-defined covalent bonding for Ca, Sr and Ba compounds. In the 25 years which have passed since Pedersen's seminal discovery, a large number of coordination compounds containing alkaline earth metals have been synthesized. In recent years, the emphasis has shifted towards the preparation of group 2 element-containing compounds which potentially can be used as precursors in the preparation of metal oxides by chemical vapor deposition [4–8]. In light of the general agreement that no “perfect” barium source presently exists for OMVPE purposes, this article will focus on general themes in group 2 element chemistry and, where relevant, correlate those themes within an integrated approach to design of new compounds of greater potential utilization for the preparation of electronic materials in thin film form.
Donor–Doped Lead Zirconate Titanate (PbZr1−xTixO3) Films
Authors: Desu Seshu B. , Vijay Dilip P. , Yoo In K. 
Published: March 2011

AbstractProperties of undoped– and doped–ferroelectric PbZr1−xTixO3. films, with both Pt or RuO2 electrodes, were compared, with a view to understand the reasons for degradation of ferroelectric films. Donor–doped (e.g., Nb5+ at Ti4+ site) PbZr1−xTixO3 films, for which the PbO loss has been compensated, showed higher resistance to fatigue and low leakage currents compared to those of undoped films. The fatigue of ferroelectric films, a decrease in switchable polarization with increasing number of polarization reversals, has been attributed to the migration of oxygen vacancies and their entrapment at various interfaces (e.g., electrode/ferroelectric interface) that are present in the film.
Vapor Deposition of Lithium Tantalate with Volatile Double Alkoxide Precursors
Authors: Chour Kueir-Weei , Wang Guangde , Xu Ren 
Published: March 2011

AbstractStoichiometric vapor deposition of LiTaO3 is demonstrated by thermal evaporation of volatile LiTa(OButn)6, controlled vapor phase partial-hydrolysis, and subsequent polycondensation reactions on a heated substrate surface. Fully dense, amorphous LiTaO3 film of up to 34 μm thick can be obtained at high deposition rate of 23 μm per hour. Single phase LiTaO3 films are obtained by annealing as deposited films. The vapor phase species responsible for the stoichiometric vapor deposition appeared to be Li2Ta2(OButn)12 from variable temperature mass spectrometry results.
Investigation of Second Harmonic Generation in MOCVD Grown Barium Titanate Thin Films
Authors: Bihari Bipin , Jiang Xin Li , Kumar Jayant , Stauf Gregory T. , Van Buskirk Peter C. 
Published: March 2011

AbstractFerroelectric Barium titanate (BaTiO3) thin films have potential applications in optical devices such as frequency doublers. Second harmonic generation (SHG) in MOCVD grown epitaxial thin films of BaTiO3 on MgO substrates is reported at an incident wavelength of 1.064 microns. A number of as-grown films show substantial second harmonic signal. Angular dependence of second harmonic intensity from as-grown films reveals that the orientation of the c-axis in these films are dependent on the growth conditions. We have examined the effect of heating and corona poling on the second harmonic generated by the samples. A higher level of SHG was observed during application of the electric field. On the removal of the poling field the second harmonic signal relaxes back. This behavior may indicate substrate-induced strain stabilization of domains.
Graphite Formation in Low Carbon Silicon Cast Irons
Authors: Chakrabarty A. K. , Kondic V. , Young J. M. 
Published: March 2011

SYNOPSISThe conditions were studied under which either eutectic graphite or carbide or both, Can form during freezing in low carbon silicon irons. Experimental variables included: iron composition, (C 1.32 to 2.17, Si 1.56 to 2.35%) small additions of alloying elements, (Ca, Mg, Al, S arid 0) and cooling rate (varying from quenching to slow cooling).Thle results obtained show that without any alloying additions these irons solidify witb the formation OF eu~tectic carbide. A fully graphitic cast structure can he readily obtained, however, with inoculating additions of either Ca or Mg. The inoculating potential of these elements increases in the presence of small amounts of Al ard 0, hut decreases with the addi tion of S. Bal ancing S with Mn restores and improves graphite nucleation by other elements. Both Ca and Mg promote spherulitic, whilst Al and high C levels, promote flake graphite morphologies. Conditions and mechanisms of formation of euitectic graphite or carbides or their mixtures in low carbon and silicon cast. irons are discussed in thle light Of current theories of solidi ficati on of east irons.
A Computer-Aided Simulation of the Kinetics of Solidification of the Eutectic Ductile Cast Iron
Authors: Edward Fras 
Published: March 2011

ABSTRACTAn attempt has been made to construct a model of the solidification of the globular eutectic grains which would account for an effect of interblocking the grain growth and would enable calculations starting with the pouring temperature and proceeding until the complete solidification of a casting is obtained. The family of equations proposed in this work enables a simulation of the kinetics of the transformation using a computer and basing only on the knowledge of the materials-designing properties of a foundry mould and the technological parameters of cast iron. The examples of computations given in the paper and the discussion of the results obtained makes it possible to explain the effect of various technological factors on the course of the solidification kinetics of a casting in the cause-effect relation.
SG Cast Iron – Influence of Hot Shakeout on the Microstructure Obtained through Varying Heat Treatments
Authors: Schissler J. M. , Saverna J. , Bellocci R. , Bak C. 
Published: March 2011

ABSTRACTAs heat treatments of metallic alloys generally require high temperatures, energy saving cycles are increasingly looked for. Castings offer the advantage over wrought products of possible hot shake out as they are just made.The object of this study was to observe the structure of a SG cast iron resulting from hot shakeout right after the end of solidification, followed or not by a 1 000°C holding and subsequent heat treatment.The austenite then presents the peculiarity of not having been re-generated by heating up from an initial structure as it is the case in conventional cycles.This study has clearly showed the influence of composition heterogeneity within the solidification cell on the response to heat treatment. Along the solidification cell boundary, an increase in carbon and manganese contents was found while silicon decreased. Along the SG nodules, the opposite is true. Between these two zones, gradients vary. The presence of these three areas results in having three different CCT curves and, therefore, a varying response to heat treatment. This is even magnified by the section size of the sample because the cell size increases, but this is minimized by the decrease in quenching rate.Structural differences observed in hot shake out samples and re-heated samples, both held or not at 1 000°C, and then cooled down, are directly related to these composition heterogeneities:- hot shakeout cast iron shows a high hardenability which varies with the holding time at 1 000°C;- after a ferritizing treatment, an homogeneous matrix is difficult to obtain from a hot shakeout cast iron;- after austempering the structural heterogeneity of the cell boundary is greater for the hot shakeout cast iron;- after the pearlitic transformation, the structure of the hot shakeout cast iron is similar to that resulting from conventional treatment.
Irreversible Carbon Diffusion in Growth of Cast Iron
Authors: Nagaoka K. , Souma M. 
Published: March 2011

ABSTRACTIn gray cast iron carbon diffuses irreversibly and the result is a growth remaining castoff voids and graphite redistribution. The origin of primary growth is in the mechanism of carbon diffusion which is controlled by a ratchet at graphite where carbon is carried by vacancy flow. Growth of flake cast iron in oxygen reduced air at low oxygen content is accounted for by self carburizing due to a reaction of penetrated oxygen and graphite flakes. For the irreversible carbon migration by gaseous carrier another ratchet is suggested. Cracking theory for primary growth is replaced by castoff void theory, and oxidation theory is modified.
The Effect of the Structure and the Heating and Cooling Rate on the Thermal Expansion of Grey Cast Iron
Authors: Sunnerkrantz P. A. , Fredriksson H. 
Published: March 2011

ABSTRACTThe thermal expansion of grey cast iron was studied in six different alloys. The expansion was determined at two different heating and cooling rates. It was found that the expansion was influenced by the heating and cooling rates. The thermal expansion was larger than the thermal expansion in steel and the thermal expansion also increased with increasing temperature. The thermal expansion was theoretically analysed. The temperature dependence was accounted for, by considering the fact that the carbon content in austenite and ferrite increases with increasing temperature.
Austempered Ductile Cast Irons–Influence of Microstructure Control
Authors: Voigt R C. , Loper C. R. 
Published: March 2011

ABSTRACTThe influence of microstructure on the properties of austempered ductile cast irons have been studied along with an analysis of the necessary process control to insure consistent properties. Both austempered ductile iron transformed at high temperatures with a matrix structure of carbide-free ferrite and substantial amounts of austenite, and austempered/bainitic ductile iron transformed at low temperatures with a more characteristic bainitic structure also containing austenite have been studied. The good toughness and ductility of these high strength ductile irons is due to the microplasticity associated with both the ferrite and austenite phases; however carbide precipitation during the later stages of austempering reduces room temperature toughness considerably and results in a change to a quasi-cleavage fracture mode. The influence of casting quality control and heat treatment control on the microstructures and properties obtained are discussed.
Influence of Silicon on Bainite Transformation in Ductile Iron; Relation to Mechanical Properties
Authors: Nieswaag H. , Nijhof J. W. 
Published: March 2011

ABSTRACTUsing a dilatometer the isothermal transformation of austenite to bainite has been studied in ductile cast iron with 0.05 % Mn and a silicon content varying from 2.4 to 3.8 %. The alloys were austenitized to a carbon content in the matrix of 0.65 %. It appears that silicon retards the formation of carbides in the upper bainite region (400 °C), resulting in an amount of retained austenite up to 40 % present in the final structure at room temperature. Silicon improves the strength; in the lower bainite region the yield strength in particular. An elongation up to 10 % or more is obtained after austempering at 400 0C independent of the silicon content.
Contribution to the Solidification and Graphitization Behavior of Sand-Cast and Gravitiy Die Cast Malleable Iron
Authors: Doepp Reinhard 
Published: March 2011

ABSTRACTStructure and properties of whitoheart malleable iron cast in gray iron permanent molds are examined. The results of test bars and industrial castings are compared to those of green sand molds. Malleable iron is predestined for casting in permanenet molds, because it must solidify completely white. Faster cooling achieved Dy the permanent mold refines primary austenite dendrites, promotes formation of ledeburite (metastable eutectic) and allows higher contents of graphitizing elements. Silicon content can be raised. The yield improves, annealing time decreases, combination of mechanical properties is improved. Combined metallurgical, technological and environmental advantages can improve economy.
The Relationship between Tensile Strength and Microstructure in Flake Graphite Cast Iron
Authors: Castillo R. N. , Baker T. J. 
Published: March 2011

ABSTRACTThe effects of composition and process variables on the tensile strength of flake graphite cast iron are well established. However, when compared with most metallic materials, there is little quantitative understanding of the way in which the microstructure controls the mechanical properties. In this paper a fracture mechanics approach is used to develop a mechanistic interpretation of the relationship between the microstructure and tensile strength. Flake graphite cast irons have been studied in which matrix microstructures of pearlite, ferrite and tempered martensite have been developed by heat treatment. For a given eutectic cell size, a linear relationship exists between the tensile strength and the fracture toughness KIC, for all of the matrix structures studied. The tensile strength is interpreted as a brittle fracture stress which is determined by the fracture toughness of the iron and an inherent defect size which is defined by the eutectic cell size.