bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dry Etching of PZT Films in an Ecr Plasma
Authors: Charlet Barbara , Davies Kerrie E. 
Published: March 2011

AbstractPZT films were etched in an ECR microwave reactor with RF polarization.The etch rate was evaluated using various gas mixtures including combinations of two of the following: C12, NF3, SF6 and HBr. The etch rate was measured as a function of the percentage of one gas in the mixture. Other parameters investigated included gas pressure, bias voltage on the electrode and substrate temperature.Results of the effect of temperature show that etch rates are higher on high temperature substrates than on low temperature substrates. A mixture of C12 and SF2 provided a PZT etch rate of 750 Å / min on a substrate, at approximately 100 °C. We evaluated the resultant etch profile and surface roughness
Optically Induced Paramagnetic Defects in PbTiO3 Single Crystals
Authors: Warren W.L. , Tuttle B.A. , Sun B.N. , Huang Y. , Payne D.A. 
Published: March 2011

AbstractOptical excitations for trivalent platinum (5d7, t6e) and trivalent Pb (6s1) ions in lead titanate single crystals have been observed for the first time by electron paramagnetic resonance (EPR). The g and hyperfine coupling, A, tensors of Pt+3 defects were found to be axial: gil∥ = 1.938, g⊥ = 2.478, A∥ = 0.0164 cm−1, and A⊥ = 0.0324 cm−1. Analysis of the EPR spectra by crystal field theory indicates that the Pt+3 ions are in tetragonally distorted (elongated) octahedral sites, strongly suggesting that they substitute for the central Ti+4 ions in the perovskite lattice. Axially symmetric Fe+3 impurities were also observed in the crystals, and they also appear to substitute for the Ti+4 cation. Identification of Pb+3 in these single crystals further shows that holes trapped at Pb+2 ions are an inherent feature of Pb-based perovskite ferroelectrics.
Preparation of SrTiO3 Thin Films by Ecr and Thermal Mocvd
Authors: Lesaicherre P-Y. , Yamaguchi H. , Sakuma T. , Miyasaka Y. , Yoshida M. , Ishitani A. 
Published: March 2011

AbstractSrTiO3 thin films were prepared by ECR and thermal MOCVD. In thermal-CVD mode, Sr content and Ti content were at a maximum at 0.56 Torr. Results showed that SrO deposition is a surface reaction limited process between 500 and 650°C, whereas TiO2 deposition is surface reaction limited between 500 and 600 °C, and diffusion limited above 600 °C. At a low pressure of 8 mTorr, ECR oxygen plasma was found to help decompose Ti(i-OC3H7)4. In ECR-CVD mode, the deposition temperature could be lowered to 400 °C. TEM and SEM analyses showed that SrTiO3 thin films have a columnar structure. The size of the grains depends on film thickness, and their shape on film composition (Sr/Ti ). Films prepared by thermal-CVD had a lateral step coverage of 50 %. 40 nm SrTiO3 thin films (Sr/Ti = 1.0) prepared by thermal-CVD on Pt/TaOx/Si and annealed for 2 hours in O2 had a maximum dielectric constant of 139 (Cs = 31 fF/μm2 and teq = 1.1 nm) and a leakage current density of 6x10−8 A/cm2 at 1.0 V.
Oxygen Tracer Diffusion in Sol-Gel Derived Pb(Zr,Ti)O3 thin Films
Authors: Vajo John J. , Momoda L.A. , Wong S.B. , Kamath G.S. 
Published: March 2011

AbstractWe have studied oxygen diffusion in thin films of Pb(Zr,Ti)O3 on Pt/Ti/SiO2/Si <100> multilayer substrates using 18O as a tracer. The PZT films were synthesized using the sol-gel technique and crystallized in air at 650° C for 30 minutes. Diffusion experiments were conducted in one atmosphere of 18O2 at tmipertures between 400-600°C, the extent of exchange was monitored using secondary ion mass spectromentry. Exchange profiles were modeled using solutions of the diffusion equation with boundary conditions for a layer with finite thickness. Significant exchange (>60%) of 16O by 18O was measured after treatment under conditions similar to those used for crystallization. At low levels of exchange, oxygen diffusion does not follow a simple Fickian profile and differences exist between nominally identical films. These results suggest that oxygen exchange is sensitive to the film's microstructure.
The Effect of Composition Dependent Lattice Strain on the Chemical Potential of Tellurium in Pb1−xSnxSe1−yTey Quaternary Alloys
Authors: Mccann Patrick J. 
Published: March 2011

ABSTRACTIV-VI semiconductor Pb1−xsSnxsSe1−ysTeys quaternary alloys were grown on (111) BaF2 by liquid phase epitaxy (LPE). X-ray diffraction analysis shows that liquid (Pb1−x1Snx1)0.99(Se1−y1Tey1)0.01 solutions produce alloys lattice-matched with the substrate wheny1 = 60%, 58%, and 57%, and x1 = 20%, 40%, and 60%, respectively. These data suggest that the chemical potential of tellurium in the Pb1−xsSnxsSe1−ysTeys solid solution decreases as tin and tellurium concentrations increase. It is argued that this reduction is due to decreasing strain energy driven segregation of tellurium from the solid to the liquid as the tin concentration increases.
Self-Accommodation Mechanisms for Orthorhombic Martensite Formation in Sputtered Thin Films of Thermoelastic Ti(Nicu)
Authors: Chang L. , Grummon D. S. 
Published: March 2011

ABSTRACTDirect observation of the self-accommodation morphology for orthorhombic martensite in Ti51.0Ni44.4Cu4.6 thin films has been accomplished by transmission microscopy of fine grained (<2μm) material prepared by triode magnetron sputtering. The films were observed to undergo, on cooling, two separate thermoelastic transformations in which the B2 austenite phase first transformed to an orthorhombic martensite with a =.291 nm, b =.425 nm and c =.450 nm followed by transformation to the monoclinic phase at lower temperature. The R-phase transformation was suppressed. Single grains contained as many as eight crystallographic variants of the orthorhombic phase, the majority of which were shaped as parallelograms bounded by {111}Ortho twin planes. The local self-accommodation mechanism produced combinations in which three adjacent variants shared a common {111}B2 pole. Although the majority of B19 variant domains accommodated themselves through {111}Ortho type twinning, a second accommodation mechanism, involving two sets of band-like martensite variants, bounded by {011}ortho twin planes, was also observed. Simultaneous occurrence of the {111}ortho and {011}ortho twinning modes, wihtin a single austenite grain, was not observed.
Strain Relief by Ion Beam Mixing. Molecular Dynamics Simulations Applied to Metallic Hetero-Structures
Authors: Mazzone A.A. 
Published: March 2011

ABSTRACTThis work presents molecular dynamics simulations of low-energy (40-80 eV) ionbeam mixing of thin metallic hetero-structures. The results indicate that the propagation of the cascade may maintain or even restore crystallinity in disordered interfacial regions.
Silicide Formation in Ti-Si and Co-Si REACTIONS
Authors: Clevengert L.L. , Hong Q.Q. , Mann R. , Harpert J.M.E. , Barmake K. , Cabral C. , Nobili C. , Ottaviani G. 
Published: March 2011

ABSTRACTTitanium silicide and cobalt silicide crystallization and formation reactions are important for the processing of CMOS circuits. We demonstrate that kinetic analysis of these reactions under both high heating rates and isothermal heating conditions allows for the determination of transformation mechanisms. For Ti/Si reactions, we show that the C49 to C54-TiSi2 transformation can not be bypassed using heating rates up to 3000°C/min. For the crystallization of CoSi2 from amorphous Co-Si thin films without ion irradiation, the crystallization kinetics are characterized by three dimensional growth from quickly consumed nucleation sites. With high dose silicon ion implantation of the as-deposited films, the crystallization mechanism changes to homogeneous nucleation and two dimensional growth.
Prediction of Silicide Formation Sequence from the Principle of the Largest Free Energy Degradation Rate
Authors: Zhang Lin , Ivey Douglas G. 
Published: March 2011

ABSTRACTRecently, a generalized kinetic model for silicide formation has been developed and a principle of the largest free energy degradation rate (largest FEDR) has been proposed. Free energy change rate as a function of diffusion flux has been derived from the kinetic model so that the principle can be justified not only for first phase formation but also for the subsequent processes. Silicide formation sequence predictions, from the model and the FEDR principle, for 15 metal-Si systems have shown very good agreement with the experimental results reported in the literature. In this paper, a brief introduction to the model and the principle is given, followed by examples of the predictions for several metal-Si systems and comparison with experimental results.
Examination of Gallium Arsenide Mocvd Reaction Mechanisms
Authors: Windeler Robert S. , Hicks Robert F. 
Published: March 2011

AbstractA mathematical model has been developed of the reactor used by Larsen et al. [1] to study the kinetics of gallium arsenide MOCVD.- Two different surface reactions were considered as the rate-limiting step in film growth below 500°C: (1) the desorption of methyl radicals from adsorbed trimethylgallium, and (2) the reaction of CH3 and H groups from adsorbed trimethylgallium and arsine to make methane. The latter step is consistent with the experimental results. It explains the rapid acceleration of the precursor decomposition rates when they are fed together to the reactor. It also explains why methane is the only hydrocarbon generated from trimethylgallium and arsine decomposition in deuterium at V/Ill ratios greater than 1.0.
Growth Mechanisms of YBa2Cu3O7-δ Thin Films Post Annealed at a Low Oxygen Partial Pressure
Authors: Hou S. Y. , Werder D. J. , Phillips Julia M. , Marshall J. H. 
Published: March 2011

AbstractThe growth mechanism of YBa2Cu3O 7-= thin films grown by the BaF2 post annealing process at low oxygen partial pressure have been studied by transmission electron microscopy. Under the annealing conditions of po2 = 4 Torr and 700°C, BaCuO2 and Y2 Cu2O5 precipitates develop from stoichiometric film precursors of YBCO during annealing. A growth model is proposed based on the observations. In addition, early stage nucleation and growth of both c- and a-axis oriented grains at the substrate interface were observed in quench annealed cross-sectional samples. 90° [100] symmetrical boundaries form between the a- and c-axis oriented grains. The possible effects of these boundaries are discussed.
Effects of Phosphorus Exposure on Arsenic-Stabilized GaAs 2×4 Surface
Authors: Bensaoula A. H. , Freundlich A. , Bensaoula A. , Rossignol V. 
Published: March 2011

AbstractPhosphorus exposed GaAs (100) surfaces during a Chemical Beam Epitaxy growth process are studied using in-situ Reflection High Energy Electron Diffraction and ex-situ High Resolution X-ray Diffraction. It is shown that the phosphorus exposure of a GaAs (100) surface in the 500 – 580 °C temperature range results in the formation of one GaP monolayer.
Temperature Dependent Quasi-Periodic Facetting of AlAs Grown by MBE on (100) GaAs Substrates
Authors: Mirin Richard , Krishnamurthy Mohan , Ibbetson James , Gossard Arthur , English John , Petroff Pierre 
Published: March 2011

AbstractHigh temperature (≥ 650°C) MBE growth of AlAs and AlAs/GaAs superlattices on (100) GaAs is shown to lead to quasi-periodic facetting. We demonstrate that the facetting is only due to the AlAs layers, and growth of GaAs on top of the facets replanarizes the surface. We show that the roughness between the AlAs and GaAs layers increases with increasing number of periods in the superlattice. The roughness increases to form distinct facets, which rapidly grow at the expense of the (100) surface. Within a few periods of the initial facet formation, the (100) surface has disappeared and only the facet planes are visible in cross-sectional transmission electron micrographs. At this point, the reflection high-energy electron diffraction pattern is spotty, and the specular spot is a distinct chevron. We also show that the facetting becomes more pronounced as the substrate temperature is increased from 620°C to 710°C. Atomic force micrographs show that the valleys enclosed by the facets can be several microns long, but they may also be only several nanometers long, depending on the growth conditions.
Epitaxial Growth of Cu Thin Films on (111)Si at Room Temperature
Authors: Liu C. S. , Chen L. J. 
Published: March 2011

AbstractEpitaxial growth of Cu thin films on atomically cleaned (111)Si has been studied by transmission electron microscopy (TEM), x-ray diffractometry (XRD) and Auger electron spectroscopy (AES). An interface compound, CuSix with x= 11.2 to 14 at.%, was observed to be present at the Cu/Si interface. Interfacial dislocations at the silicide/Si interface were identified to be of edge type with 1/2<110> Burgers vectors. η“-Cu3Si was found to form in samples annealed at 200 °C for 1 h. Solid phase epitaxial growth of silicon on (111)Si was observed to occur at a temperature as low as 200 °C. Polycrystalline η”-Cu3Si is the only phase present in samples annealed at 200–800 °C. In samples annealed at or higher than 850 °c, a mixture of η′-Cu3Si and η“-Cu3Si were found to be present.
From Adatom Migration to Chemical Kinetics: Models for MBE, Mombe and MOCVD
Authors: Vvedensky D. D. , Shitarat T. , Smilauer P. , Kaneko T. , Zangwill A. 
Published: March 2011

AbstractThe application of Monte Carlo simulations to various epitaxial growth methods is examined from the standpoint of incorporating only those kinetics processes that are required to explain experimental data. A basic model for molecular-beam epitaxy (MBE) is first introduced and some of the features that make it suitable for describing atomic-scale processes are pointed out. Extensions of this model for cases where the atomic constituents of the growing surface are delivered in the form of heteroatomic molecules are then considered. The experimental scenarios that is discussed is the homoepitaxy of GaAs(001) using metalorganic molecular-beam epitaxy (MOMBE) with triethylgallium (TEG) and precursors and using MOCVD with trimethylgallium (TMG). For MOMBE, the comparisons between simulations and experiments are based on reflection high-energy electron diffraction intensities, by analogy with comparisons made for MBE, while for metalorganic chemical vapor deposition (MOCVD) the simulations are compared to in situ glancingincidence x-ray scattering measurements. In both of these cases, the inclusion of a second mobile species to represent the precursor together with various rules for the decomposition of this molecule (in terms of rates and local environments) with be shown to provide a useful starting point for explaining the general trends in the experimental data and for further refinements of the model.
Crystallographic Analysis of (110)CeO2/(100)Si Using RBS/Channeling Technique
Authors: Satoh Masataka , Yamamoto Yasuhiro , Nakajima Shigeyuki , Sakurai Yoshinobu , Inoue Tomoyasu , Ohsuna Tetsu 
Published: March 2011

AbstractEpitaxially grown CeO2 layers on (100)Si substrates are studied using the RBS/channeling technique. The crystallographic correlation between the overgrown layers and off-oriented Si substrates is precisely analyzed by means of constructing stereographic projections obtained from the planar channeling dips. From the stereographic projections for the CeO2 layer on the 4° off-oriented Si substrate, it is clearly seen not only that the epitaxial (110)CeO2 layer is single crystal with the direction defined as [001]CeO2 ║ [011]Si, but also that the crystalline quality of (110)CeO2 on (100)Si can be improved by use of the off-oriented substrate. The inclined epitaxial direction is also detected as the depth information.
Dislocations Nucleating Growth in Liquid Phase Epitaxy of Gallium Arsenide
Authors: Möhling Werner , Weishart H. , Bauser E. 
Published: March 2011

AbstractDislocations in GaAs are analysed by X-ray topography in order to relate their nature to their efficiency in generating growth steps. The analysis is mainly based on comparing double crystal back reflection images of the defects to calculated misorientations of the crystal surface which are caused at the outcrop. All types of dislocations are equally effective provided their Burgers vector has a component normal to the growth interface. Concentric growth step patterns, which develop in varying numbers on different samples are not caused by substrate dislocations.
Evolving Surface Cusps During Strained Layer Epitaxy
Authors: Jesson D. E. , Pennycook S. J. , Baribeau J.-M. , Houghton D. C. 
Published: March 2011

AbstractWe have combined Z-contrast imaging and Ge marker layer experiments to study the evolving surface morphology of SixGel-x alloys grown by molecular beam epitaxy (MBE). Surface cusps are seen to arise as the intersection lines between coherent islands. The potential implications of stress concentrations associated with cusps are considered with a view to strain relaxation in the film via dislocation nucleation.
Effects of Minimizing the Driving Force for Epitaxy in the Ge/Si(001) System
Authors: Hansson P. O. , Bauser E. , Albrecht M. , Strunk H. P. 
Published: March 2011

AbstractA new technique for Ge/Si heteroepitaxy from the solution, referred to as interfacial energy epitaxy, produces Ge layers with atomically abrupt interfaces to Si and permits monolayer-controlled growth at temperatures up to 937°C. The initial driving force for epitaxy comes from interfacial energy differences between Ge, Si, and the solvent or growth mediator, whose surface free energy has to be smaller than that of Ge. A superheating of the growth solution partly out-balances this driving force, which allows us to minimize the total driving force for epitaxy. Two-dimensional growth results. Subsequent faceting and pseudomorphic island growth manifest additional driving forces for epitaxy, which may be due to interfacial- and strain energy gain.
Strain-Field Induced Crosshatch Formation During Molecular Beam Epitaxy of InGaAs/GaAs Films
Authors: Zhou X. C. , Jiang J. , Du A. Y. , Zhao J. W. , Mu S. M. , Peng L.-M. , Zhong Z. T. 
Published: March 2011

AbstractUsing reflection electron microscopy (REM), transmission electron microscopy (TEM), and Nomarski optical microscopy we obtained direct evidence that local surface strain-fields, originated from misfit dislocations, are responsible for the formation of morphological crosshatches during molecular beam epitaxy of lattice mismatched InGaAs/GaAs layers. A mechanism is proposed to correlate the formation of the crosshatched patterns with the variation of the growth rate across the epitaxial surface under the perturbation of network shaped strain-fields in the surface.
Molecular Dynamics Simulations of Diamond and Carbon Clusters
Authors: Pailthorpe Bernard A. 
Published: March 2011

ABSTRACTThe synthesis of amorphous diamond thin films has been studied previously by classical molecular dynamics computer simulations utilising Stillinger Weber potentials, reparameterised to describe bonding in carbon. The simulations provided insight into the surface processes occuring during thin film growth and showed the role of stress and an energy window in promoting amorphous diamond formation from carbon ion beams. However, more realistic simulations require a full treatment of quantum effects to describe adequately chemical bonding and electronic properties. Local Density Functional theories and the Car-Parrinello molecular dynamics algorithm have proved to be successful and offer a route to first-principles materials design. We are using these techniques to investigate bonding and structure in small carbon clusters and to study doping of diamond required to fabricate electronic devices. Results are presented for a novel, three dimensional, neutral carbon-11 cluster which was studied by ab initio molecular dynamics simulations confirming that, while the 3D structure is stable, the ring is the lower energy structure. However, the 3D structure deforms rapidly to a more open structure of the same topology which is dynamically stable during simulated annealing up to 2000K. Higher quality calculations indicate that new, lower symmetry bonding arrangements form also. Attempts to enclose lithium or boron atoms within the Cl 1 cage caused heating and ultimate rupture into smaller fragments.
Helium Ion Beam Induced Arsenic Atom Displacement Studied by Medium-Energy Ion Spectroscopy
Authors: Yokoyama Shin , Radzimski Zbigniew J. , Ishibashi Kensaku , Watanabe Takeshi , Hirose Masataka 
Published: March 2011

ABSTRACTAn arsenic atom displacement in As+ ion implanted Si induced by He+ ion beam irradiation has been studied by medium-energy (175keV) ion spectroscopy (MEIS). The He+ energy and dose dependences of the displaced arsenic atoms have been examined in the range of 30-175keV and ≤6×10-4C/cm2, respectively. The amount of the displaced arsenic atoms are found to be proportional to the dose and inversely proportional to the nuclear stopping power in the low-dose region, while it saturates at high-dose region. The dose-proportional region is composed of two different proportional coefficient segments.
Nanosized Thallium Inclusions in Aluminium
Authors: Johnson E. , Johansen A. , Bourdelle K.K. , Andersen H.H. , Sarholt-Kristensen L. 
Published: March 2011

ABSTRACTIon implantation of pure aluminium with thallium induces formation of nanosized crystalline thallium inclusions with either fee or bee structure. The size of the inclusions depends on the implantation conditions and subsequent annealing treatments. Inclusions less than 10-15 nm in size are generally fee while larger inclusions are bee. The fee inclusions are aligned topotactically with the aluminium matrix with a cube/cube orientation relationship, and they have a truncated octahedral shape bounded by {111} and {001} planes. The lattice parameter of the fee thallium inclusions is 0.484 nm ± 0.002 nm, which is slightly but significantly larger than for the high pressure fee thallium phase known to be stable above 3.8 GPa. The lattice parameter of the bec inclusions is close to the equilibrium value of 0.387 nm and the orientation relationship is given by the Kurdjumov-Sachs rule (011)bcc ║ (111)fcc and [111]bcc ║ [101]fcc The bec inclusions,, representing the high temperature equilibrium phase but existing in metastable equilibrium at lower temperatures, have curved and less well-defined facets. Inclusions with hep structure, the stable phase at room temperature, have not been observed.