bluuebunny/crossref_metadata_2025_split huggingface dataset:
Confinement and Low-Energy Extraction of Photo-Fragment Ions Using Rf Ion Trapping
Authors: Yamamoto Seiji , Mochiji Kozo , Ochiai Isao , Mikami Naohiko 
Published: March 2011

AbstractSpatial confinement of mass-selected ions and extracting them to a solid surface at low kinetic energy is achieved by using rf ion trapping which is combined with multi-photon ionization by a KrF laser. SF5+ fragment ions of SF6 generated by photo-ionization are separated from other ionic species and then confined in the cylindrical ion trap cell for at least 100 ms. The stored ions are extracted onto the seniconductor surface. This technique is promising for clarifying surface reactions of semiconductors, which is the key to controlling surface structure on an atomic scale.
The Impact of Gas Phase and Surface Chemical Reactions on Step Coverage in Lpcvd
Authors: Raupp Gregory B. , Cale Timothy S. 
Published: March 2011

AbstractThe characteristic step coverage behavior which a given LPCVD process exhibits depends on the nature of the controlling gas phase and/or surface chemical reactions. Physically-based ballistic transport and reaction film profile evolution simulation has provided a structure wherein the origins of step coverage limitations can be understood in the context of the interaction of transport and the controlling chemistry. Based on comparisons of the simulations to literature and in-house experimental data, we have categorized LPCVD mechanisms into one of three types. In heterogeneous deposition, conformal step coverage can usually be found under at least some process conditions. Step coverage typically degrades with increasing deposition temperature. In homogeneous precursor-mediateddeposition, a reactive intermediate is formed in the gas-phase above the wafer surface, resulting in poor to moderate step coverage. Step coverage may or may not degrade with increasing temperature. In byproduct-inhibited deposition, a gas-phase byproduct generated via a surface reaction readsorbs on the growing film surface and slows the deposition rate, yielding a poor to moderate, relatively temperature-insensitive step coverage. Poor step coverage is manifested in a marked film thickness discontinuity at the feature mouth, with a relatively uniform film down the feature sidewalls.
Surface Reaction Intermediates in Ge Chemical Vapor Deposition on Silicon
Authors: Greenlief C. Michael , Keeling Lori A. 
Published: March 2011

AbstractComputational programs are often used for estimating molecular orbital energies and geometries. The results of these calculations can also provide information needed for investigation of adsorption and decomposition mechanisms on surfaces. In this study, ab initio methods are used to calculate properties of gas phase diethylgermane and GeHx-substituted silanes (x=1−3). The silanes are used as models for surface Ge hydrides. The calculated gas phase molecular orbital energies are then compared with experimentally determined molecular orbital energies for the adsorbed species. The surface species are prepared by germane, digermane, ethylbromide, or diethylgermane adsorption on the Si(100)-(2×1) surface and the molecular orbital energies are measured by photoelectron spectroscopy.
Direct Measurement of the Reactivity of NH and oh on a Silicon Nitride Surface
Authors: Buss R. J. , Ho P. , Fisher E. R. , Breiland William G. 
Published: March 2011

AbstractIn order to understand and successfully model the plasma processing used in device fabrication, it is important to determine the role played by plasma-generated radicals. We have used the IRIS technique (Imaging of Radicals Interacting with Surfaces) to obtain the reactivity of NH(X3∑-) and OH(X2II) at a silicon nitride film surface while the film is exposed to a plasma-type environment. The reactivity of NH was found to be zero both during exposure of the surface to an NH3 plasma and during active deposition of silicon nitride from a SiH4/NH3 plasma. No NH surface reaction was detectable for any rotational states of NH and over a surface temperature range of 300-700 K. OH radicals generated in an H2O plasma were found to have a reactivity of 0.57 on a room temperature oxidized silicon nitride surface. The OH reactivity falls to zero as the temperature of the substrate is raised.
Thermodynamic Simulation of MOCVD YBa2Cu3O7−x Thin Film Deposition
Authors: Bernard C. , Weiss F. , Pisch A. , Madar R. 
Published: March 2011

AbstractChemical Vapour Deposition of YBa2Cu3O7−x superconductors using organometallic precursor materials involves the formation of a great variety of condensed phases (oxides, carbonates, hydroxides, carbides, hydrides) and a complex gas phase. Therefore, the possibility of calculating the stability ranges of the different phases susceptible of being deposited and the influence of the main experimental parameters (precursor partial pressure, oxygen partial pressure, total pressure, temperature) is very attractive. Recently, some initial attempts have been published, but the authors did not have sufficiently complete and reliable thermodynamic data on the species involved in the process. These results will be discussed. Furthermore, a homogeneous and complete set of data for the whole system will be presented, and the reactions of the deposition process will be simulated on the basis of this data set. The most important results will be compared to the previous calculations and to recent experimental work.
Thermodynamic Constraints for the In Situ MOCVD Growth of Superconducting Tl-Ba-Ca-Cu-O Thin Films
Authors: Holstein William L. 
Published: March 2011

AbstractIn spite of several attempts, superconducting Tl-Ba-Ca-Cu-O thin films have not been successfully prepared in situ by metal organic chemical vapor deposition (MOCVD). Preparation of a phase by MOCVD requires that it be thermodynamically stable with respect to its decomposition into volatile species and other condensed phases. For MOCVD growth of Tl-Ba- Ca-Cu-O compounds in the presence of oxygen from reagents containing only C-H or C-H-O ligands, Tl2O(g) and TIOH(g) exhibit appreciable volatility. If reagents with ligands containing fluorine are used, the formation of volatile TIF(g) must also be considered. Thermodynamic data for these materials are compiled, and thermodynamic relationships between these gases, H2O(g) and HF(g) are established. The thermodynamic stability of TIOH(g) and TIF(g) makes the in situ growth of Tl-Ba-Ca-Cu-O compounds by MOCVD more difficult than their in situ growth by physical vapor deposition processes, for which Tl2O(g) is the only volatile TI-containing species present.
Electro-Optic Materials by Solid Source MOCVD
Authors: Hiskes R. , Dicarolis S. A. , Fouquet J. , Lu Z. , Feigelson R. S. , Route R. K. , Leplingard F. , Foster C. M. 
Published: March 2011

AbstractThe solid source MOCVD technique1,2, employing a single powder vaporization source composed of mixed beta-diketonate metalorganic compounds, has been used to grow thin films of a variety of electro-optic materials, including lithium niobate, strontium barium niobate, and potassium niobate. Results for potassium niobate films are quite preliminary, but indicate that a volatile potassium organometallic source can be synthesized which is useful for growing potassium niobate by MOCVD. High quality single phase (001) oriented strontium barium niobate films have been deposited which exhibit waveguiding behavior. The most extensive work has been done on lithium niobate, which has been deposited epitaxially on a variety of substrates. Oriented z-axis (001) films have been grown on c-axis sapphire with and without a (111) oriented platinum base electrode and on a bulk grown lithium niobate substrate. Films grown directly on c-axis sapphire at 700 C exhibit x-ray rocking curve linewidths as low as.044 degrees, nearly perfect in-plane orientation as determined by x-ray phi scans, and peak-to-peak surface roughness less than 40 Å. Optical waveguiding has been demonstrated by a single prism coupling technique on similar films 1175 – 2000 Å thick grown at 500 C, with optical losses of approximately 2 db/cm at 632.8 nm measured over 3.5 cm long films. Polarization vs. electric field measurements on 1100 Å thick films grown on platinum show a hysteresis loop indicating ferroelectric behavior.
MOCVD of Magneto-Optical Ceramics
Authors: Okada Masaru , Katayama Shigehisa , Kamiya Tadashi 
Published: March 2011

AbstractBismuth-substituted yttrium iron garnet, BixY1−xFe5O12 thin films have been epitaxially grown on a Gd3Ga5O12 (111) substrate at 750°C under reduced pressure (6 Torr), with a deposition rate of 20∼50nm·min−1 by MOCVD. The maximum value of Faraday rotation was −7.5×104deg·cm−1at a Bi-content of 2.5 atoms per formula unit. The Figure of unit was 14.30 deg., which is significantly larger than that obtained by sputtering. On the other hand, cerium-substituted films could not be obtained even at elevated temperatures, 900°C.
Chemical Vapor Deposition of Vanadium Oxide Tiiin Films
Authors: Stewart Ogie , Rodriguez Joan , Williams Keith B. , Reck Gene P. , Malani Narayan , Proscia James W. 
Published: March 2011

AbstractVanadium oxide thin films were grown on glass substrates by atmospheric pressure chemical vapor deposition (APCVD) from the reaction of vanadium(IV) chloride with isopropanol and t-butanol. Films were deposited in the temperature range 250 to 450°C. The as-deposited films were a dark greenish color consistent with formation of a lower oxide of vanadium. Annealing a film deposited on Corning 7059 glass in air converted the material to a yellow film. X-ray diffraction of the yellow film revealed the presence of V2O5. Optical spectra of the films are presented. Glass substrates previously coated with conductive fluorine doped tin oxide were coated with V2O5 and evaluated for electrochromic activity.
Low Temperature MOCVD of Oriented PbTiO3 Films on Si(100)
Authors: Chen H. , Yen B.M. , Bai G.R. , Liu D. , Chang H.L.M. 
Published: March 2011

AbstractHighly oriented PbTiO3 (PT) thin films have been successfully grown on Si(100) using MOCVD technique at as low as 450°C. Titanium isopropoxide, Ti(C3H7O)4, tetraethyl lead, Pb(C2H5 )4, and pure oxygen were chosen as precursor materials in this work. The resulting film chemistry and texture were found to be strongly dependent on Pb/Ti source flow ratio and growth temperature.
Preparation of Ba1−xSrxTiO3 Thin Films by Metalorganic Chemical Vapor Deposition and Their Properties
Authors: Gilbert S. R. , Wessels B. W. , Neumayer D. A. , Marks T. J. , Schindler J. L. , Kannewurf C. R. 
Published: March 2011

AbstractBa1−xSrxTiO3 thin films were deposited over the entire solid solution range by low pressure metal-organic chemical vapor deposition. The metal-organic precursors employed were titanium tetraisopropoxide and barium and strontium(hexafl uoroacetylacetonate)2·tetraglyme. The substrates used were LaAlO3 and (100) p-type Si. Ba1−xSrxTiO3 films deposited on LaAlO3 were epitaxial, while the films deposited on Si showed no texture. Auger spectroscopy indicated that single phase Ba1−xSrxTiO3 films did not contain detectable levels of fluorine contamination. The dielectric constant was found to depend upon the solid solution composition x, and values as large as 220 measured at a frequency of 1 MHz were obtained. The resistivities of the as-deposited films ranged from 103 to 108 Ω-cm. Temperature dependent resistivity measurements indicated the films were slightly oxygen deficient.
Growth of (001)-Oriented Sbn Thin Films by Solid Source MOCVD
Authors: Lu Z. , Feigelson R. S. , Route R. K. , Hiskes R. , Dicarolis S. A. 
Published: March 2011

AbstractBy the solid source MOCVD technique, we have deposited 2000 – 3000 Å thick single phase SrxBa1−xNb2O6 (SBN) films on (100) MgO substrates using tetramethylheptanedionate (thd) sources. X-ray diffraction (XRD) 2θ scans indicated that these films were completely (001) oriented. XRD Φ scans, however, showed the films contained four in-plane grain orientations whose volume fractions could be controlled by altering the Sr/(Sr+Ba) and Nb/(Sr+Ba) ratios in the source powders. The in-plane volume fractions did not change with the deposition rate or the cooling rate. Films with composition Sr0 58Ba0.42Nb1.94O6 had mainly two in-plane orientations. Optical waveguiding behavior was demonstrated in these films. Refractive indices were found to be no= 2.20 and ne = 2.13, as compared to no = 2.31 and ne = 2.27 for bulk SBN60.
Lead Titanate Thin Films Prepared by Metallorganic Chemical Vapor Deposion (MOCVD) on Sapphire, Pt, and RuOx Substrates
Authors: Hendricks Warren C. , Desu Seshu B. , Peng Chien H. 
Published: March 2011

AbstractTransparent and highly specular PbTiO3 thin films were deposited on sapphire, platinum and ruthenium oxide-coated silicon wafers by hot-wall metallorganic chemical vapor deposition (MOCVD). Lead bis-tetramethylheptadionate and titanium ethoxide were used as chemical precursors. Films were deposited over a range of experimental conditions. X-ray diffraction (XRD) was used to determine the phases present in the films; Scanning Electron Microscopy (SEM) was used to examine the surface morphology and Energy Dispersive Spectroscopy (EDS) was used to determine the composition. Optical spectra were obtained to confirm the highly dense and transparent nature of the films. The chemical stability of the ruthenium oxide substrates in the MOCVD environment as well as the existence of a high-temperature deposition regime for composition control are also discussed.
Partition of alloying elements on eutectic solidification of cast iron
Authors: Kagawa Akio , Okamoto Taira 
Published: March 2011

ABSTRACTThe coefficients for partition of an alloying element (X) between austenite and liquid iron (), and between eutectic liquid and its solid (PS and PM in the stable and metastable eutectic solidifications, respectively) have been investigated thermodynamically. The coefficient depended significantly on the interaction between carbon and the element X. A simplified method for the evaluation of was introduced from the thermodynamic analysis of factors influencing on . The coefficients, PS and PM, calculated from and the coefficient for partition of the element X between cementite and ausfenite, agreed well with those obtained experimentally. It was indicated from the thermodynamic stability for the coexisting phases that the effect of an alloying element on graphitization occurring during eutectic solidification wvs closely related to the values of Δ(+PM-PS and and also to the effect of the element on the difference between the stable and metastable eutectic temperatures. No strict relation was found between the effects of an alloying element on the carbon activity in liquid iron and on the graphitization.
Graphite Morphology in Cast Irons
Authors: Loper Carl R. 
Published: March 2011

ABSTRACTGraphite structures formed during the cooling of molten cast irons and during their solidification were examined in alloys as a function of composition, treatment (magnesium and/or rare earths) and inoculation. The effect of cooling rate and solidification conditions on the morphology of the resultant graphite was investigated using a variety of techniques (optical and scanning electron microscopy, etching procedures, etc.) to reveal the growth characteristics of this phase and its relationship to other phases developing during the solidification process. These graphite forms have been classified according to their morphology and the factors affecting their development. Examples of these graphite forms are presented and their growth conditions and charateristics analyzed.Kish graphite is shown to form, not as a result of internal development in a melt and subsequent flotation to the surface, but by a surface growth mechanism forming extensive graphite plates. Proeutectic graphite also forms in the melt just prior to the appearance of the eutectic, however, its growth in the absence of austenite is shown to be limited.While a variety of graphite morphologies have been identified in eutectic solidification, it is shown that these graphite shapes may develop from the same nucleation sites, that growth conditions determine the graphite morphology, and that as the growth conditions are altered the morphology of the resultant graphite is correspondingly affected. The transition between graphite shapes such as flake, compacted, spheroidal, exploded, etc. is depicted in various microstructures.In addition, the relationship between certain compounds (e.g., titanium carbo-nitride, etc.) and graphite growth is demonstrated and discussed.
Formation and Prevention of Chunky Graphite in Slowly Cooled Nodular Irons
Authors: Xi Tang Chong , Fargues J. , Hecht M. , Margerie J. C. 
Published: March 2011

ABSTRACTAn experimental device has been designed in order to simulate the solidification of large castings by means of a small-sized sample (1 kg). Once the spheroidizing and inoculation processes have been completed, this sample is slowly cooled at controlled rate and under protective atmosphere in an insulated crucible placed in a laboratory resistance furnace. The maximum freezing time is about 90 min. These tests relate to a base iron having a good degree of purity.SEM, optical microscopy and automated electron microprobe have been used for studying structure and mechanism of chunky graphite formation.Results of over forty tests confirm several data abstracted from literature and provide some more information. For instance, there are different ways of preventing chunky graphite formation : acceleration of solidification, use of Ni-Mg or pure Mg as spheroidizers and, in any case, an antimony addition (0,02%).A rather low carbon equivalent is also a favourable factor. However, for a given carbon equivalent, a final relatively high Si content improves graphite spheroidizing, chunky graphite appearing only if this content results from Fe-Si-Mg additions and/or from overinoculation.Besides, confirmation is given of the detrimental effect of useless rare earth additions (e.g. 0,02%).The matrix surrounding chunky graphite is on average more rich in Si than the one surrounding spheroidal graphite. An oxidizing etching reveals that chunky eutectic has formed at first.Aiming an interpretation of the results, structure examination keeps going on, in order to find out if there could be several kinds of chunky graphite.
Impurity Incorporation During Si Ultrafast Solidification to the
Crystalline and Amorphous Phase
Authors: Ugo Campisano Salvatore 
Published: March 2011

ABSTRACTImpurity segregation at the liquid-solid interface, interfacial
instabilities due to constitutional supercooling and precipitation are
compared for the growth of a crystalline or of an amorphous phase from rapid
solidification. Segregation at low concentration and interfacial
instabilities at high concentrations are shown to give the same information.
The impurity behaviour shows a distinct similarity between the crystalline
and amorphous phases.
Fundamental Aspects of High Speed Crystal Growth from the
Melt
Authors: Cullis A.G. 
Published: March 2011

ABSTRACTAdvances in the study of high speed crystal growth from the melt are
reviewed, with special emphasis on the fast melting and solidification of
silicon achieved by use of Q-switched laser radiation pulses. Rapid melting
of amorphous Si is confirmed to yield a liquid undercooled by several
hundred Kelvins and, under suitable conditions, explosive crystal growth
processes can occur. The latter involve the self-sustaining propagation of
melt bands buried within the initially amorphous material. When the highest
quench-rate conditions are established melting of even crystalline Si can
yield a final amorphous solid phase. This breakdown in crystal growth is
orientation dependent and can give regimes of crystal defect formation when
amor-phization does not take place. The processes which characterize this
limiting growth behaviour are discussed.
A Test of Two Solute-Trapping Models
Authors: Aziz M. J. , Tsao J. Y. , Thompson M. O. , Peercy P. S. , White C. W. , Christie W. H. 
Published: March 2011

ABSTRACTTwo solute trapping models are compared. They are shown to predict identical
behavior at any given end of a phase diagram but different behavior as the
phase diagram is traversed. The segregation behavior of dilute solutions of
Ge in Si (ke < 1) and of Si in Ge (ke > 1) during regrowth from
pulsed-laser melting is being studied using transient conductance, high
resolution RBS, and SIMS. Our results to date suggest a significant amount"
of solute trapping (k —> 1) of Ge in Si and of Si in Ge. Such a result
would be inconsistent with the predictions of one of the models.
Modeling of Undercooling, Nucleation, and Multiple Phase Front
Formation in Pulsed-Laser-Melted Amorphous Silicon
Authors: Wood R. F. , Geist G. A. , Solomon A. D. , Lowndes D. H. , Jellison G. E. 
Published: March 2011

ABSTRACTRecently available experimental data indicate that the solidification of
undercooled molten silicon prepared by pulsed laser melting of amorphous
silicon is a complex process. Time-resolved reflectivity and electrical
conductivity measurements provide information about near-surface melting and
suggest the presence of buried molten layers. Transmission electron
micrographs show the formation of both fine- and large-grained
polycrystalline regions if the melt front does not penetrate through the
amorphous layer. We have carried out extensive calculations using a newly
developed computer program based on an enthalpy formulation of the heat
conduction problem. The program provides the framework for a consistent
treatment of the simultaneous formation of multiple states and phase-front
propagation by allowing material in each finite-difference cell to melt,
undercool, nucleate, and solidify under prescribed conditions. Calculations
indicate possibilities for a wide variety of solidification behavior. The
new model and selected results of calculations are discussed here and
comparisons with recent experimental data are made.
Low-Energy, Pulsed-Laser Irradiation of Amorphous Silicon:
Melting and Resolidification at Two Fronts
Authors: Sinke W. , Saris F.W. 
Published: March 2011

ABSTRACTAfter low-energy pulsed-laser irradiation of Cu-implanted silicon, a
double-peak structure is observed in the Cu concentration profile, which
results from the occurrence of two melts. From Cu surface segregation we
calculate the depth of the surface melt. Cu segregation near the position of
the amorphous-crystalline interface gives evidence for a self-propagating
melt, moving from the surface region towards the crystalline substrate.
Measurements of As-redistribution and of sheet resistance as a function of
laser energy density in As-implanted silicon are consistent with the
crystallization model which is derived from the effects as observed in
Cu-implanted silicon.The results imply a large difference in melting temperature, heat
conductivity and heat of melting between amorphous silicon and crystalline
silicon.
Overheating and Undercooling in Silicon During Pulsed-Laser
Irradiation
Authors: Larson B. C. , Tischler J. Z. , Mills D. M. 
Published: March 2011

ABSTRACTWe have used time-resolved x-ray diffraction measurements of thermal
expansion induced strain to measure overheating and undercooling in
<100> and <111> oriented silicon during pulsed laser melting and
regrowth. 249 nm (KrF) excimer laser pulses of 1.2 J/cm2 energy
density and 25 ns FWHM were synchronized with x-ray pulses from the Cornell
High Energy Synchrotron Source (CHESS) to carry out Bragg profile
measurements with ±2 ns time resolution. Combined overheating and
undercooling values of 120 ± 30 K and 45 ± 20 K were found for the
<111> and <100> orientations, respectively, and these values
have been used to obtain information on the limiting regrowth velocities for
silicon.