bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface and Interface Damage Characterization of Reactive Ion Etched MBE Regrown GaAs
Authors: Cole M.W. , Dutta M. , Rossabi J. , Smith D.D. , Lehman J.L. 
Published: March 2011

AbstractDamage resulting from reactive ion etching (RIE) and wet etching of MBE grown GaAs and the defects generated in subsequent GaAs regrowth was evaluated by Transmission Electron Microscopy (TEM), photoluminescence (PL) , and Raman spectroscopy. The samples were reactively etched with HCl and Cl2 at two power densities; 0.3 W/cm2 and 0.6 W/cm2. A wet chemical (H2O:H3PO4:H2O2) etched sample was used for comparison. The LO phonon intensities measured by room temperature Raman spectroscopy showed a strong correlation to the relative PL intensities, where the HCl sample was found to be inferior to the others. TEM microstructural evaluation showed both HCl RIE samples to have significant interface roughness, with the sample etched at 0.6 W/cm2 showing the most structural damage in the regrowth region. Defect densities for the Cl2. and wet etched samples were two orders of magnitude lower than that of the HCl etched samples. The extent of disorder in the regrowth region was largest for the HCl sample with respect to the Cl2 and wet etched samples. These microstructural and optical results suggest that the H+ ion plays an important role in the generation of crystal defects during the RIE process.
Preparation and Characterization of Molybdenum Disulfide Microcrystals in Colloidal Dispersion
Authors: Lu E. , Persans P. D. , Ruppert A. F. , Chianelli R. R. 
Published: March 2011

AbstractWe report the preparation and general, optical and resonant Raman scattering characterization of MoS2 platelets suspended in an insulating organic liquid. Structural results indicate that the platelets are predominantly 2H in structure and are about 500Å in diameter and 50–90 Å thick. The optical constants of the composite are close to those expected from the simple Maxwell-Garnett effective medium theory. We have observed resonant enhancement of the Raman cross-section for the MoS2 phonon mode at 408 cm−1 as the laser excitation energy is scanned through the “B” exciton.
Transport Properties of B-, P-Doped and Undoped 50 kHz PECVD Microcrystalline Silicon
Authors: Hachicha M.A. , Bustarret Etienne 
Published: March 2011

AbstractUndoped 500 nm-thick silicon layers with a crystalline fraction around 95% and an average grain size of 20 nm have been deposited at 350°C by 50 kHz triode PECVD in a H2/SiH4 mixture, in the presence of a magnetic field. Their room temperature (rt) dc conductivity μrt is 0.03 Δ−1cm−1 for a Hall mobility of 0.8 cm 2V−1s−1.The study by SIMS, infrared absorption, grazing angle x-ray diffraction and Raman scattering spectroscopies of the doped samples shows how the crystalline fraction and the grain size drop as the B2H6/SiH4 and PH3/SiH4 volumic ratios increase from 10 ppm to 1%.The rt dc conductivity reaches 2 Δ−1 cm−1 (Hall mobility: 15 cm2V−ls−1) for a solid phase density of 1019 cm−3 boron atoms, and 30 Δ−1cm−1 (Hall mobility: 55 cm2V−ls−1) at the maximum P incorporation of 8 × 1020cm−3.
Properties of Binary Si:H Materials Prepared by Hydrogen Plasma Sputtering
Authors: Furukawa Shoji , Miyasato Tatsuro 
Published: March 2011

AbstractBinary Si:H materials are prepared by means of the rf sputtering technique in pure hydrogen atmosphere on low temperature (about 100 K) and room temperature substrates. The physical properties of the obtained materials are very much affected by the rf power and substrate temperature during the deposition. The material prepared at a low substrate temperature with a low rf power has a wide optical gap, and shows a visible photoluminescence at room temperature. On the other hand, the material prepared at room temperature with a high rf power contains many Si microcrystals, whose diameters are relatively large, and its optical gap becomes very small. The latter condition causes the dependence of the crystalline direction of the material film on the substrate crystal even at the room temperature. An rf power-modulated multi-layered structure (superlattice) is also proposed, and an apparent diffraction peak can be observed in the low-angle X-ray scattering measurement.
Preparation and Characterization of Highly Conductive (100 S/cm) Phosphorus Doped νc-Si:H Films Deposited Using the VHF-GD Technique
Authors: Prasad Kshem , Finger F. , Curtins H. , Shah A. , Bauman J. 
Published: March 2011

AbstractWe report on the preparation and characterization of phosphorus doped gc-Si:H films produced by the very high frequency glow discharge (VHF-GD) at a plasma excitation frequency of 70 MHz. We present a systematic study of the deposition parameters i.e. hydrogen dilution of silane, VHF power density, gas phase doping ratio and deposition temperature and their influences on the electrical and structural properties of the material. In contrast to 13.56 MHz GD the VHF plasma conditions favour microcrystalline formation at low power densities; the resulting conductivities are significantly higher than those obtained at 13.56 MHz.
Preparation of High-Quality poly-Si and μc-Si Films by the SPC Method
Authors: Matsuyama T. , Nishikuni M. , Kameda M. , Okamoto S. , Tanaka M. , Tsuda S. , Ohnishi M. , Nakano S. , Kuwano Y. 
Published: March 2011

AbstractWe have achieved the highest total area conversion efficiency for an integrated type 10cm × 10cm a-Si solar cell at 10.2%. This value is the world record for a 10cm × 10cm a-Si solar cell. For further improvement of conversion efficiency in a-Si solar cells, it is necessary to develop materials with high-photosensitivity in the long wavelength region and materials with high conductivity. We have developed a Solid Phase Crystallization (SPC) method of growing a Si crystal at temperatures as low as 600°C. Using this method, thin-film polycrystalline silicon (poly-Si) with higP-photosensitivity in the long wavelength region and Hall mobility of 70cm2/V sec was obtained and quantum efficiency in the range of 800,∼ lO00nm was achieved up to 80% in the n-type poly-Si with grain size of about 2μm. We also succeeded in preparing a device-quality p-type microcrystalline silicon (μc-Si) using the SPC method at 620°C for 3 hours from the conventional plasma-CVD p-type amorphous silicon (a-5i) withoul using any post-doping process. Obtained properties of μd=2 × 103 (.cm) and a high optical transmittance in the 2.0 ∼ 3.0 eV range are better as a window material than the conventional p-type μc-Si:H. Therefore, it was concluded that the SPC method is better as a new technique to prepare high-quality solar cell materials.
Time-Resolved Spectra of Edge Emission of Cdse Mesoscopic Clusters in GeO2 Glass Matrix
Authors: Inokuma Takao , Ishikawa Mitsuru , Tanaka Akinori , Arai Toshihiro 
Published: March 2011

AbstractTime-resolved edge emission spectra of CdSe clusters were measured at 80K. Cluster size and excitation Intensity dependences of the decay behavior were discussed in terms of the quantum size effect for electronic states.
Characterization of the Plasma Chemistry and Film Composition of PECVD Silicon Nitride Deposited from Silane-Nitrogen and Silane-Ammonia Mixtures with Argon Additions
Authors: Quinn W. E. , Bagley B. G. , Wilkens B. J. , Gallois B. M. 
Published: March 2011

AbstractSilicon nitride films deposited from silane-nitrogen and silane-ammonia mixtures by PECVD contain large amounts of hydrogen. We have determined that adding argon to the gas mixture reduces the amount of hydrogen in the resulting films. Differences in film composition are obviously due to changes in the chemistry of the discharge which was characterized by line-of-sight mass spectrometry, optical emission spectroscopy and plasma double probe measurements. Substrate temperature was fixed at 325°C, pressure was 500 mtorr, the RF power was 0.25 watts cm−2, the silane to nitrogen ratio was varied from 0.003 to 0.02, the silane to ammonia ratio was varied from 0.01 to 0.5, and the argon additions were 10% of the total gas flow. Argon additions to the discharge increased the plasma density in both nitrogen and ammonia plasmas. Optical emission from N2 and Si-H species increased upon the addition of 10% argon to the silane-nitrogen discharge, whereas the N-H emission decreased upon addition of argon to the silane-ammonia discharge. Infrared transmission spectra of films deposited with and without argon show no change in peak position or intensity of Si-H and N-H absorption bands in the spectral range studied, despite a large (over 20%) reduction in hydrogen content, as determined by nuclear profiling, upon the addition of argon. These results suggest that a substantial fraction of the hydrogen in the films is not infrared active. We propose that the reduction in hydrogen content is due to bombardment of the growing film by argon ions, which sputter the adsorbed hydrogen molecules.
The Plasma Deposition of Semiconductor Multilater Structures
Authors: Hirose Masataka , Miyazaki Seiichi 
Published: March 2011

AbstractThe early stages of thin film deposition from the rf glow discharge of SiH4 or SiH4 + NH3 have been studied by analysing the structure of silicon based multiiayers consisting of hydrogenated amorphous silicon (a-Si:H, 10 – 200 A thick) and stoichiometric silicon nitride (a-Si3N4:H, 25 – 250 A) alternating layers. The x-ray diffraction, its rocking curve and x-ray interference of the multilayers have shown that the amorphous silicon/silicon nitride interface is atomically abrupt and the surfaces of the respective layers are atomically flat regardless of substrate materials. This indicates that the precursors impinging onto a substrate from the gas phase homogeneously cover the growing surface and the layer by layer growth proceeds on atomic scale. In the plasma deposition of the covalently bonded semiconductors and insulators, the island formation on a substrate surface at the beginning of the thin film growth is very unlikely.
In-Situ Gas Conversion Using a Wide Area Disc Shaped He-H2 Plasma and Organometallic Feedstocks
Authors: Pihlstrom B. , Sheng T. , Yu Z. , Collins G. 
Published: March 2011

AbstractA wide area disc shaped plasma source of 20cm in diameter generated by a ring shaped cathode electron beam is used to decompose Trimethylgallium (TMGa) and Trimethylarsenic (TMAs). Volume photo-absorption of VUV photons and sensitized atom-molecule collisions with excited species and radicals can all assist dissociation of the organometallic feedstock reactants. In addition, the excited radical flux and VUV impingement on the film may also assist heterogeneous surface reactions and increase surface mobility of absorbed species. Mass spectrometry studies using deuterium as a replacement for hydrogen as a trace gas allowed for the elicidation of decomposition pathways of TMGa and TMAs. Byproducts of hydrogen and helium plasmas were also studied.
The Effect of Reactor Pressure on the Growth of Glow Discharge a-SiN:H
Authors: Varhue W. J. , Pandelisev K. A. 
Published: March 2011

AbstractThe electrical resistivity and N content of a-SiN:H films can be controlled by varying the reactor pressure. This appears to be a result of the increased dissociation of the ammonia feed gas by the change in the electron energy spectrum. The effect of ion bombardment of the substrate surface does not result in observable changes in film quality.
A Neutron Reflectivity Study of the Interfacial Magnetism of an Y/Gd Film
Authors: Ankner J.F. , Zabel H. , Neumann D.A. , Majkrzak C.F. , Matheny A. , Dura J.A. , Flynn C.P. 
Published: March 2011

ABSTRACTUsing the technique of polarized-neutron reflectometry, we have studied the magnetic moment distribution in the interfacial region of an epitaxial film consisting of 97 Å Y(0001) atop 1000 Å Gd(0001). At T = 151 K, with an 80 gauss field applied parallel to the surface (basal plane), we observe two distinct ferromagnetic regions: the Gd bulk and a layer with reduced magnetic moment at the Y/Gd interface. Above the bulk Curie temperature, at T = 295 K , we observe no net magnetization in either the bulk or the interface.
The Study of Surfaces and Interfaces on the Reflectometer Crisp at the Isis Pulsed Neutron Source
Authors: Penfold J 
Published: March 2011

ABSTRACTThe study of surfaces and interfaces using the specular reflection of neutrons on the reflectometer CRISP at the ISIS pulsed neutron source is discussed. The instrumentation, is briefly described, and the performance of the spectrometer being illustrated by some standard examples. Recent experimental results on the adsorption of surfactants at the air-water interface will be presented.
Polarization Relaxation in KDP-Isomorph Ferroelectrics
Authors: Homer Vicki , Edge Ronald 
Published: March 2011

ABSTRACTThe two-dimensional position sensitive detector at IPNS was used to probe the splitting of a single Bragg peak of the ferroelectric KD2PO4 (DKDP) at temperatures below the Curie point. The (440) peak was split into four components as the crystal itself divided into four domains. When the crystal was subjected to electric fields of sufficient strength and duration, these peaks would change in relative intensity, thus displaying the rearrangement of the domain structure as the crystal changed its level of polarization. Even at temperatures 15–20K below the Curie point, the polarized crystal was observed to relax back to an almost completely unpolarized state upon removal of the applied electric field. This indicates that the true coercive field for the crystal at this temperature was much smaller than values previously reported [l]. Low frequency dielectric constant studies using a capacitance bridge have since been conducted, which confirm and expand on these results.
Neutron Powder Diffraction Study of the Structures of La1.9Ca1.1Cu2O6 and La1.9Sr1.1Cu2O6+δ
Authors: Santoro A. , Beech F. , Cava R. J. 
Published: March 2011

ABSTRACTThe title compounds are structurally isomorphous and crystallize with the symmetry of space group 14/mmm. The lattice parameters are a = 3.8248(1), c = 19.4286(5)Å for La1.9Ca1.1Cu2O6 and a = 3.8601(1), c = 19.9994(5)Å for La1.9Sr1.1Cu2O6+δ. The structure can be easily derived from that of La2CuO4 by substituting the layers of composition CuO2 present in La2CuO4 with a block of three layers having composition and sequence (CuO2) - (R) - (CuO2), where R is Ca, Sr, and/or La. Although the general structural configuration is the same for the Ca and the Sr compounds, the distribution of the metal atoms is different in the two cases. More specifically, in La1.9Ca1.1Cu2O6 the perovskite-type layers form blocks with sequence (CuO2) - (Ca) - (CuO2), and are separated by rock-salt blocks of two layers (LaO) - (LaO). In La1.9Sr1.1Cu2O6+δ, on the other hand, the perovskite-type blocks have composition and sequence (CuO2) - (R) - (CuO2) and they are separated by blocks (NO) - (NO), where both R and N are about 65%La and 35%Sr.
The Advanced Neutron Source
Authors: Hayter John B. 
Published: March 2011

ABSTRACTThe Advanced Neutron Source (ANS) is a new user experimental facility planned to be operational at Oak Ridge in the late 1990's. The centerpiece of the ANS will be a steady-state research reactor of unprecedented thermal neutron flux (φth ≍ 9·1019 m−2·s−1) accompanied by extensive and comprehensive equipment and facilities for neutron-based research.
Neutrons: The Kinder, Gentler Probe of Condensed Matter
Authors: Axe John D. 
Published: March 2011

ABSTRACTNeutrons play an increasingly important role in the characterization of advanced modern materials. They provide information that complements rather than competes with that provided by other scattering probes. Although neutrons require heroic efforts to produce, the techniques for using them are not particularly difficult, and with the advent of sufficient user friendly facilities, are becoming a routine tool in the arsenal of expanding numbers of materials scientists.
Neutron Depth Profiles of Boron Implanted Semiconductors
Authors: Bowman Robert C. , Knudsen John F. , Downing R. Gregory 
Published: March 2011

ABSTRACTThe nondestructive neutron depth profile (NDP) technique has been used to measure boron (10B) distributions in Si and Hg0.7Cd0.3 Te after multiple energy ion implants. The NDP results are compared with simulations generated by TRIM and SUPREM computer codes. The influence of SiO2 films on the boron profiles was examined and the effects of thermal anneals are also described.
Neutron Scattering Study of Layered Silicates Pillared with Alkylandnonium Ions
Authors: Neumann D. A. , Nicol J. M. , Rush J. J. , Wada N. , Fan Y. B. , Kim H. , Solin S. A. , Pinnavaia T. J. , Trevino S. F. 
Published: March 2011

ABSTRACTIncoherent, inelastic neutron scattering has been used to study the vibrational spectra of tetramethylammonium montmorillonite and trimethylammonium vermiculite in the energy range 20–140 meV. For both systems peaks are observed due to the internal modes of the intercalate and to the excitations of the hydroxyl groups within the host layers. For the montmorillonite sample, it is found that the steric constraints imposed on the tetramethylammonium ion by the bounding clay layers contribute an additional 28 meV to the rotational barrier of the methyl groups. This additional barrier is shown to be strongly related to the volume that the tetramethylammonium ion occupies. For the trimethylammonium vermiculite sample normal mode analysis of the internal modes of the intercalated ion shows that the N-H bond is parallel to the c-axis of the host.
Analysis of Sans from Controlled Pore Glasses
Authors: Berk N. F. , Glinka C. J. , Haller W. , Sandert L. C. 
Published: March 2011

ABSTRACTSmall angle neutron scattering measurements have been performed on several samples of silica controlled pore glasses with pore sizes ranging from roughly 7 to 30 nm. The scattering intensity is strongly peaked at small Q and shows approximate Porod law behavior at large Q. Contrast variation measurements have shown that the pore space in these samples is entirely interconnected and thus forms a bicontinuous microstructure. The scattering data have been analyzed using the leveled wave method based on an early scheme for representing two-phase microstructures resulting from spinodal decomposition. In this approach interfaces are modeled by the contours of a stochastic standing wave composed of plane wave components propagating in random directions with random phases and having wave numbers distributed according to a given probability density, P(k). We have determined model P(k) functions by fitting the SANS data with the leveled wave scattering function and then used these to construct leveled wave images of the corresponding porous structures. The average pore sizes obtained by measuring chord lengths in the computer models turn out to agree with the values determined for these glasses by mercury porosimetry.
Shear Induced Phase Behavior of Polymer Blends by Small Angle Neutron Scattering
Authors: Nakatani Alan I. , Kim Hongdoo , Han Charles C. 
Published: March 2011

ABSTRACTThe phase behavior of polymer blends and solutions can be changed dramatically by a flow field using a variety of flow geometries. Unlike simple binary fluids which require extremely high shear rates to produce only small shifts in the phase boundary, polymer phase behavior may be influenced by as much as 10 degrees with the application of much lower shear rates. However, there is a large body of conflicting data concerning the nature of these shear effects in polymers.Here we report on the effects of shear on the phase behavior of polymer blends by small angle neutron scattering (SANS). Experiments were conducted using a specially constructed, concentric cylinder apparatus for in situ studies of concentrated polymer solutions and melts. Two separate systems will be discussed: 1) a blend of polystyrene and polybutadiene. 2) a blend of polystyrene and poly(vinylmethylether). Both systems exhibit shifts in the phase behavior which indicate shear induced mixing in agreement with previous results obtained by other techniques. These results will be interpreted within the context of existing theories of shear induced phase behavior.
Fracture of Metal-Polymer Interfaces with Fine-Line Geometries
Authors: Chiu Shih-Liang , Jeng Y. H. , Acosta Raul E. , Ho Paul 
Published: March 2011

AbstractThe fracture behavior of metal-polymer line structures as a function of dimensions was investigated using a stretch-deformation technique. The effects of line orientation, line width and film thickness are reported in this paper. When the line orientation is parallel to the stretching direction, only formation of cracks normal to the lines is observed. However, when the line is perpendicular to the stretching direction, delamination becomes the dominant mode of fracture. Wide lines (16μm) exhibit larger shear stress at the edge of the metal-polymer interface, thus delaminate earlier than narrow lines (4μm). By decreasing the metal film thickness, the depth of stress penetration at the interface decreases, making the propagation of cracks more difficult in thin films than in thick films.Finite element analysis was carried out to account for the experimental observations and good agreement was obtained. In the analysis, the plastic deformation characteristics of the metal and the polymer have been specifically taken into account. In comparison with a linear elastic analysis, the linear model predicts significantly higher stress levels and local concentrations than the nonlinear model.
Preparation of Al2 O3 -Coated Metal Substrate for High Density Electronic Assembly
Authors: Nakada K. , Ono M. , Kosuge S. 
Published: March 2011

AbstractA study was conducted on the preparation of Al2 O3 -coated metal substrates for high density electronic assembly. Al2 O3 films of 3∼15μm thickness were deposited on metal substrates, such as aluminum, stainless steels and the like, at a deposition rate of 0.2∼5μm/min. They were examined in terms of chemical composition, microstructure, density, hardness, breakdown voltage, thermal conductivity and so on. It was found that the dense and stoichiometric films could be achieved by adjusting the process parameters, in particular, substrate temperature, deposition rate and distance between target and substrate. The results obtained led to the conclusion that this new Al2O3-coated metal substrate could be effective for high density electronic assembly.
The Fast Firing of the Ferroelectric Relaxor Pb(Mn1/3Nb2/3).02 (Mg1/2 W1/2 ).48 Zr.23 Ti.27O3
Authors: Mansfield Sean F. , Taylor Jenifer A.T. , Barus Aristianto M. , Landin Steven M. 
Published: March 2011

AbstractThe possibility of fast firing a relaxor dielectric to suppress grain growth, mitigate the lead loss and reduce the cost of sintering has been investigated. The relaxor Pb(Mn1/3 Nb2/3).02 (Mg1/2 W1/2 ).48 Zr.23 Ti.27 O3 [1] exhibits a highly desirable broad phase transistion range when the prbcessing procedures are carefully controlled and fired conventionally. When fast fired, this material's density, percentage of secondary phases, and dielectric constant were highly dependent on the sintering time. A sample fired for 6 minutes possessed a dielectric constant nearly equal to the same material conventionally fired for 16 hours.
Materials, Mechanical, and Thermal Considerations of High Density Multi-Chip Electronic Packages
Authors: Krusius J. Peter 
Published: March 2011

AbstractMulti-chip packages (MCP) are analyzed for high density CMOS packaging using package system simulation, a new systematic methodology for design and trade-off studies of electronic packages. Technology parameters for a representative CMOS chip, multi-chip package, and printed wiring board technology are defined. The effect of these technology parameters on the characteristics of the MCP are examined. The MCP's are optimized using simulated annealing. A large set of optimum MCP's has been found. Based on this set, MCP technology parameters are ranked and their implications on future high density MCP's discussed.