bluuebunny/crossref_metadata_2025_split huggingface dataset:
High Quality Heteroepitaxial ß-SiC Deposited from Methyltrichlorosilane at 1200°C without any Buffer Layer
Authors: Vepřek S. , Kunstamann Th. , Hofmann J. , Volm D. , Meyer B. 
Published: April 2011

ABSTRACTUsing methyltrichlorosilane diluted with hydrogen and a modified temperature program during the initial stage of the deposition we have improved the deposition process and obtained high quality heteroepitaxial films on Si (100) without any carbon buffer layer. The maximum temperature of 1200°C which is used for the substrate cleaning and film deposition is significantly lower than that used in the conventional deposition system SiH4/C3H8 of about 1400°C for the buffer layer and 1350°C for deposition.
Semiconductor Epitaxial and Nonepitaxial Overgrowth from Solutions
Authors: Köhler R. , Raidt H. , Banhart F. , Jenichen B. , Gutjahr A. , Konuma M. , Silier I. , Bauser E. 
Published: April 2011

ABSTRACTHaving grown semiconductor-on-insulator (SOI) layers by liquid phase epitaxy (LPE) we have investigated their properties by x-ray topography, optical-, atomic force- and high resolution electron microscopy and by etching experiments.A first series of experiments was carried out on (111)-oriented Si substrate wafers which were partially masked by thermal oxide. Area- selective LPE, which was then applied and followed by epitaxial lateral overgrowth (ELO), yielded SOI layers of high quality. Silicon SOI layers had aspect ratios of up to 65 and were typically dislocation-free. These highly perfect SOI structures facilitated studies of the specific processes for semiconductor lateral growth over amorphous layers. Vertical stresses were detected in the substrate-layer systems. They were found to influence the shapes of the SOI layers. Our studies suggest that here is a model case for solution growth of thin semiconductor lamellae on dissimilar substrates.Subsequently, a second series of experiments consisted in having SiGe lamellae grown in the same fashion. These experiments confirm that the same morphology is observed for Ge-contents up to 2 percent.
Low-Temperature Growth and Structural Characterization of GaAs Using Ionized Source Beam Epitaxy
Authors: Roh D.-W. , Kim K. 
Published: April 2011

ABSTRACTSingle-crystal GaAs films were grown on SI (100) GaAs at substrate temperatures below 200 °C by using ionized source beam epitaxy. The correlation between the properties of the films and the growth parameters, in particular, the substrate temperature, the amount of As-source beam ionization, and the acceleration voltage of the As beam was investigated to elucidate the possible benefits of source beam ionization and acceleration on low-temperature thin film growth. The use of ionized and accelerated As-source beam greatly improved the quality of the low-temperature grown GaAs film. The surface morphology, crystallinity, and micro structure of the low temperature grown GaAs films were evaluated using in situ reflection high energy electron diffraction, double crystal X-ray diffraction, and cross section transmission electron microscopy.
Uniform Quantum Dots by Self-Organizing Process in Atomic Hydrogen-Assisted MBE
Authors: Chun Y.-J. , Nakajima S. , Okada Y. , Kawabe M. 
Published: April 2011

ABSTRACTThe effects of atomic hydrogen (H) on formation of In(Ga)As quantum dots (QDs) by self-organizing process have been investigated. The low size fluctuation and uniform-shaped QDs are obtained at growth temperature above 450°C. The average size of InGaAs QDs are decreased from 40 nm to 20 nm by atomic H irradiation. The InGaAs QDs are formed uniformly on growth surface in with-H condition while preferentially formed and distributed along the step edges in without-H case. The photoluminescence (PL) peak intensities and full width at half maximum (FWHM) are also improved by atomic H irradiation. The waiting time before GaAs cap layer deposition is a important factor on the optical properties of QDs.
A Model for Ion-Assisted Molecular Beam Epitaxy and Application to Synthesis of Epitaxial SNxGE1-x Alloy Films
Authors: He Gang , Atwater Harry A. , Watson Thomas J. 
Published: April 2011

ABSTRACTIn this work, we develop a model for ion-assisted molecular beam epitaxy with application to synthesis of epitaxial SnxGe1-x/Ge/Si(001) with compositions up to x=0.34. The model describes the effect of energetic beam deposition on surface segregation during thin film growth. As the value of a Péclet number expressing the ratio of surface ion-mixing rate to growth rate exceeds unity, the segregation coefficient during ion-assisted growth exceeds the value during thermal growth. A comparison of the model with experiments for SnxGei.1-x synthesis is reported. The experimental results are consistent with the model.
Dislocation Structure Evolution in Thin Single Crystal Plates Under Cyclic Loading
Authors: Stepanov Yury. N. , Scorupsky Alexander M. 
Published: April 2011

ABSTRACTThe effect of cyclic uniaxial loading applied to surfaces of thin single crystal plates on dislocation structure is analyzed analytically and numerically. This work investigates detailed changes in dislocation structure near surfaces and in size and concentration of dislocation loops inside the crystal. The results may be helpful in choosing the optimum regime for material processing and in predicting material properties.
Scaling of Island Size Distributions in the Growth of Ni on GaAs(110)
Authors: Quesenberry P. E. , First P. N. 
Published: April 2011

ABSTRACTIsland size distributions have been derived from scanning tunneling microscope (STM) images of Ni deposited on cleaved GaAs(110) at room temperature and above. For submonolayer coverages, this system forms 3-dimensional (3-D) reacted islands with the degree of reaction dependent upon the growth temperature. As has been found for other systems, the average island size (sαυ) increases with temperature. The high temperature data (∼ 150° C) shows two distinct island types, each with substantially different average size. The island size distributions have maxima at the smallest island sizes. For different coverages, plots of the area-normalized island size distributions versus the scaled variable s/sαυ show significant differences. However, above a cutoff value for s/sαυ the distributions can be renormalized to fall on a common curve. These characteristics and direct atomic-scale evidence are consistent with nucleation of islands via adatom-substrate exchange, but the temperature dependence of the total island density appears to be inconsistent with this being the only first-order rate process taking place.
Decomposition of Unstable Supersaturated Cu90Co10 Solid Solutions
Authors: Busch Ralf , Gärtner Frank , Borchers Christine , Haasen Peter , Bormann Rüdiger 
Published: April 2011

AbstractHomogeneous Cu90Co10 alloys were prepared by rapid solidification using the meltspin technique. The decomposition process of this highly supersaturated unstable solid solution was investigated on a nanometer scale using a combination of atom probe field ion microscopy (AP/FIM) analyses and transmission electron microscopy.Annealing of the Cu90Co10 alloys at 440°C for various times leads to the formation of a compositional modulated microstructure within the grains. The composition profiles determined by AP/FIM analyses clearly exclude a classical nucleation and growth behavior of Co-rich particles. The microstructure is modulated with two different wavelengths. In addition, chemical ordering perpendicular to [111] directions of the fee lattice is observed.At the grain boundaries of this alloy, heterogeneous nucleation of pure Co particles is observed. This heterogeneous nucleation process competes with the decomposition within the grains.
Which Systems Can Undergo Inverse Melting?
Authors: Sinkler W. , Michaelsen C. , Bormann R. 
Published: April 2011

AbstractIn the process of inverse melting, a crystalline solid solution on cooling becomes less energetically stable than the isocompositional undercooled liquid or amorphous phase. Due to this, the crystal may transform polymorphously to the amorphous or liquid phase. A thermodynamic requirement for this process is the presence of two crossing points of the free energy curves G(T) of the crystalline and liquid or amorphous phases. Fulfillment of the thermodynamic requirement is however not a sufficient criterion for inverse melting to occur. In the present work the question posed in the title is addressed from both a thermodynamic as well as a kinetic standpoint. It is shown that in bcc phases which would otherwise undergo inverse melting, the presence of an energetically favorable B2 phase may prevent inverse melting due to its fast ordering kinetics. This imposes an e/a limit to the occurrence of inverse melting.
Mechanisms of Phase Formation During Milling in the Ternary Immiscible AG-CU-FE System
Authors: Klassen T. , Herr U. , Averback R.S. 
Published: April 2011

AbstractPowder blends consisting of prealloyed FCC Ag-Cu solid solutions and elemental Fe powders were ball milled in overall compositions of Ag25Cu50Fe25, andAg40Cu20Fe40. The phase evolution with milling time was investigated by x-ray diffraction and differential scanning calorimetry. For the sample with higher Cu concentration, a ternary FCC alloy phase was formed, while milling the other sample resulted in a two phase mixture consisting of a Ag-rich FCC and an Fe-rich BCC solid solution. About the same amount of enthalpy between 12 and 13 kJ/g-atom is stored in the final states for the two different compositions. Two models based on kinetic and energetic considerations will be discussed and compared to the results. The kinetic model is based on the competition between forced atomic motion during shearing, which is driving the system towards a homogeneous alloy, and thermally activated diffusion, which favors phase separation. For the energetic model, the energy balance is calculated and a phase transformation is expected, if the required energy can be stored in phase boundaries.
Enhanced Electrical Conductivity and Nonstoichiometry in Nanocrystalline CeO2-x
Authors: Lavik E.B. , Chiang Y.-M. , Kosacki I. , Tuller H.L. 
Published: April 2011

AbstractDense nanocrystalline CeO2-x. of ∼10 nm grain size exhibits enhanced, PO2-dependent electronic conductivity indicative of intrinsic nonstoichiometric behavior under conditions where coarse-grained counterparts are extrinsic. The enthalpy of reduction is lowered by over 2.4 eV per oxygen vacancy. The nanocrystals also exhibit greatly reduced grain boundary resistance, attributed to grain-size-dependent segregation. We propose that interface doping by selected low energy defect sites dominates the defect and transport properties of nanocrystalline ceria, and possibly other nanocrystalline compounds.
Synthesis and Characterization of Nanocrystalline M50 Steel Powders by Cryomilling
Authors: Lau M. L. , Huang B. , Perez R. J. , Nutt S. R. , Lavernia E. J. 
Published: April 2011

AbstractThe present study investigated the synthesis of nanocrystalline high speed steel M50 (4.5% Mo, 4.0% Cr, 1.0% V, 0.8% C, balance Fe) by cryogenic high energy ball milling (cryomilling). Pre-alloyed M50 steel was spray atomized, and subsequently cryomilled in liquid nitrogen for 25 hours. Elemental Al powder was added prior to cryomilling in order to promote the formation of nanoscale Al2O3 and AlN particles, which improved the thermal stability of the nanocrystalline M50 steel. Following annealing at 1373 K, the M50 steel was found to retain its nanocrystalline microstructure with the average grain size of 40–80 nm.
Production and Technical Characteristics of a New Class of Amorphous Metals
Authors: Malkhassian R.T. 
Published: April 2011

AbstractA new technology for obtainment of amorphous single-component metals is presented.For the first time the reduction of molybdenum oxide with formation of its amorphous phase is realized in conditions of a given quantum-chemical technology by means of vibrationally excited to the third quantum level hydrogen molecules with 1.5 ± 0.2 eV energy. The evidences of formation of this nonequilibrium amorphous phase are presented along with certain physicochemical properties of the obtained amorphous molybdenum.A model is proposed for the origin of amorphous phase under the influence of nonequilibrium quantum-chemical technology.
Kinetics and Mechanism of the C49 to C54 Titanium Disilicide Phase Transformation in Nitrogen Ambient
Authors: Nagabushnam R. V. , Sharan S. , Sandhu G. , Rakesh V. R. , Singh R. K. , Tiwari P. 
Published: April 2011

AbstractThe kinetics of the C49 to C54 TiSi2phase transformation in nitrogen ambient have been investigated in a temperature range from 700 °C to 800 °C for a range of titanium film thicknesses (135 Å to 350 Å) using sheet resistance measurement, Auger electron spectroscopy(AES), Rutherford backscattering spectroscopy(RBS) and transmission electron microscopy(TEM). About 80% of the titanium converts to titanium silicide with the rest converting to titanium nitride. The activation energies obtained for the C49 to C54 transformation in nitrogen ambient are lower, at least by 2–2.25 eV, than that obtained for the transformations occuring either in argon ambient or vacuum environment. This has been explained with a model involving stress state of titanium silicide film with titanium nitride overlayer.
Titanium Germanosilicide Phase Formation During The Ti-Si1-xGex Solid Phase Reactions
Authors: Aldrich D. B. , Chen Y. L. , Sayers D. E. , Nemanich R. J. 
Published: April 2011

AbstractThe effect of Si1−xGex alloy composition on the titanium germanosilicide phase formation sequence during the Ti-Si1−xGex solid phase reaction was examined. For the Ti-Si reaction the initial formation of C49 TiSi2 is followed, at higher temperatures, by the formation of C54 TiSi2. For the Ti-Ge reaction the initial formation of Ti6Ge5 is followed, at higher temperatures, by the formation of C54 TiGe2. It was determined that the Ti-Si1−xGex reaction follows three different reaction paths depending on the composition of the initial Si1−xGex alloy. For Si rich Si1−xGex alloys the Ti-Si1−xGex reaction follows a “Ti-Si like” reaction path (Ti+M ↠ C49 TiM2 ↠ C54 TiM2, where M = Si1−xGex). For Ge rich Si1−xGex alloys the reaction follows a “Ti-Ge like” reaction path (Ti+M ↠ Ti6M5 ↠ C54 TiM2). Both Ti6M5 and C49 TiM2 form during the reaction of titanium with Si1−xGex alloys in an intermediate composition range. Properties of the final C54 phase were observed to be strongly dependent on the phase formation sequence. Smooth continuous C54 titanium germanosilicide forms during the “Ti-Si like” reaction and discontinuous islanded C54 titanium germanosilicide forms during the “Ti-Ge like” reaction. An optimum Si1−xGex alloy composition range of 0.00 ≤ x ≤ 0.36 was determined for the formation of continuous- low-resistivity- C54 titanium germanosilicide films from the solid phase reaction of Ti and Si1−xGex alloy.
Effects of Growth Parameters on the Epitaxy of CoSi2/Si(100) Formed by Reactive Deposition Epitaxy
Authors: Vantommela André , Degroote Stefan , Dekoster Johan , Bender Hugo , Langouche Guido 
Published: April 2011

AbstractEpitaxial CoSi2(100) layers in the thickness range of 20 to 50 nm have been formed by reactive deposition epitaxy (i.e. Co deposition onto a hot Si substrate) without the use of either a template or an intermediate Ti layer. It is explained how growth parameters such as the deposition rate and substrate temperature are crucial in determining the epitaxial nature of the silicide. According to this model, good CoSi2/Si(100) alignment is only achieved when very low deposition rates are used (0.1 Å/s or less), combined with relatively high substrate temperatures during deposition (∼ 600°C or higher). Using these conditions, highly strained, continuous CoSi2 layers with a channeling minimum yield of χmin = 9% could be formed. Using higher rates and/or lower deposition temperatures, an increasing fraction of misoriented CoSi2 grains is presumed from backscattering/channeling and x-ray experiments, the nature of which is under investigation with plan view and cross sectional transmission electron microscopy.
Disorder and Strain Effects in the Optical Response of Thin CoSi Epitaxial Films on Si(111)
Authors: Bocelli S. , Guizzetti G. , Marabelli F. , Schwarz C. , Goncalvesconto S. , Von Känel H. 
Published: April 2011

AbstractThin (CsCl)CoSi films of thicknesses from 44 to 105 Å were grown by MBE at room temperature onto ultrathin annealed CoSi2 templates. Also two CoSi2 films of about 100 Å with the CaF2 structure and with the defected CsCl structure were obtained epitaxially.Far infrared reflectance and transmittance measured on such samples show optical structures between 240 and 370 cm-1. In the range 1.4–5 eV spectroscopic ellipsometry was performed, too. A change in the optical response was revealed among the different samples, which can be ascribed to strain, roughness and/or disorder at the interfaces.
Indentation Fracture Studies of a BaTiO3 Thin Film on a Silicon Substrate
Authors: Ho Wai-Ming , Fu Ran , Wan Kai-Tak , Chou Ji , Zhang Tong-Yi 
Published: April 2011

AbstractIt has been experimentally and theoretically found that the critical applied stress intensity factor for indentation cracking also depends linearly on the reciprocal of the square root of crack length when the indentation fracture technique is used to measure residual stresses in thin films.
Polycrystalline β-SiC Film Growth on Si by ECR-CVD at 178 - 500°C
Authors: Cheng Kuan-Lun , Liu Chih-Chien , Fu Chung-Min , Cheng Huang-Chung , Lee Chiapyng , Yew Tri-Rung 
Published: April 2011

AbstractPolycrystalline β-SiC, with grain size up to 0.2 μm, was grown on silicon substrate by electron cyclotron resonance chemical vapor deposition (ECR-CVD) from SiH4/CH4/H2 at 178–500 °C. The nucleation process and surface structure of polycrystalline SiC were investigated via observing the film surface by atomic force microscopy (AFM). Reaction species which promote polycrystalline SiC was in-situ monitored by quadruple mass spectrum analysers during deposition process, which is crucial for the control of polycrystalline SiC growth. The microstructure of SiC films were inspected by bright-field imaging, dark-field imaging, and electron diffraction in cross-sectional transmission electron microscopy. This paper will also discuss the key parameters for the nucleation and growth of polycrystalline β-SiC at very low temperature in ECR-CVD system.
Growth and Characterization of Hard Nitrides Films Prepared by Pulsed Laser Deposition
Authors: Inturi R. B. , Kumar Ashok , Ekanayake U. , Shu N. , Barnard J. A. 
Published: April 2011

AbstractTransition metal of nitrides have many desirable properties for application at elevated temperatures because of extremely high melting point, hardness, high temperature strength, good thermal shock resistance, and high thermal conductivity. We have investigated the thin film coatings of nitrides (titanium nitride, and composite carbon nitride) on various commercial useful substrates by the pulsed laser deposition (PLD) method. The PLD method is unique process for depositing high quality thin films with novel microstructure and properties. The laser parameters: energy density, pulse rate, target/substrate distance and substrate temperature have been optimized to improve the quality of thin films. The mechanical properties of the films have been evaluated at different processed conditions by nanoindentation technique. The films were characterized by X-ray diffraction, scanning electron microscope and FTIR techniques. Optimization of laser deposition parameters to obtain high quality thin films will be discussed in detail.
Development of High-Performance GaAs Solar Cells on Large-Grain Polycrystalline Ge Substrates
Authors: Venkatasubramanian R. , O'Quinn B. , Hills J. S. , Timmons M. L. , Malta D. P. 
Published: April 2011

AbstractThe characterization of MOCVD-grown GaAs-AlGaAs materials and GaAs p+n junctions on poly-Ge substrates is presented. Minority carrier lifetime in GaAs-AIGaAs double-hetero (DH) structures grown on these substrates and the variation of lifetimes across different grainstructures are discussed. Minority-carrier diffusion lengths in polycrystalline GaAs p+-n junctions were evaluated by cross-sectional electron-beam induced current (EBIC) scans. The junctions were also studied by plan-view EBIC imaging. Optimization studies of GaAs solar cell on poly-Ge are discussed briefly. The effect of various polycrystalline substrate-induced defects on performance of GaAs solar cells are presented.
Effects of Cu and Si Dopants on Electromigration Mass Transport in Al Interconnects for VLSI
Authors: Lee C. H. , Fejes P. L. , York B. R. , Elwell S. A. , Carnes R. O. , Lee J. Y. , Grivna G. M. , Bauguess S. W. , Dreyer M. L. , Edwards S. R. 
Published: April 2011

AbstractWe have investigated the effects of Cu and Si dopants on electromigration mass transport in Al interconnects for VLSI technology. Four Al alloys with different Cu and Si dopant concentrations (AI-1.5%Cu, AI-1.5%Cu-I.5%Si, AI-0.5%Cu-I.0%Si, and AI-I.O%Cu-I.0%Si) were sputter deposited onto Si substrates covered with 0.55 pRm of Si02 (tetraethylorthosilicate). All metal films were deposited using an MRC903 sputter deposition system to a thickness of 6800Å. Deposition parameters were held constant for each metallurgy, with a base pressure of 7x 10−2 torr, deposition pressure of 102 torr, forward power of 7 Kwatts, and substrate bias of 125 volts. Test structures designed according to National Institute of Standards design guidelines were fabricated in each metallurgy using conventional photolithography and reactive ion etching methods for line widths of 1.0, 1.8, 3.0, 5.0 and 10.0 μm. Accelerated test conditions of T=200°C and DC current density of 2x106 A/cm−2 were used. The results show that electromigration resistance increases with increasing Cu content and decreases as Si content increases. These results are explained in terms of precipitate, grain size distribution, orientation and stress by Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD). Our results provide a general guideline relating Cu and Si dopant concentrations, film microstructure and the intrinsic reliability of the metallization system.
Microstructure and Optical Properties of Aluminum Nitride Thin Films
Authors: Watanabe Yoshihisa , Nakamura Yoshikazu , Hirayama Shigekazu , Naota Yuusaku 
Published: April 2011

AbstractPolycrystalline aluminum nitride (AIN) thin films have been synthesized by ion-beam assisted deposition method and the effect of ion beam energy on the film structure and optical properties has been studied. The kinetic energy of nitrogen ion beam was varied from 0.05 to 1.5 keV under the constant current density. Microstructure of films was examined by thin film X ray diffraction (TFXRD) and optical transmission spectrum from 220 to 2200 nm was measured by UV-visible spectrometer. The TFXRD studies show that the (00*02) plane of hexagonal AIN grows preferentially with the ion beam energy of 0.05 keV and the intensity of the (10*0) and (10*1) planes becomes strong with increasing the ion beam energy. The optical measurements reveal that the wavy structures due to the interference effect are observed in the transmission spectra and the wavy pattern decreases with increasing the ion beam energy, resulting in the decrease of refractive index.