bluuebunny/crossref_metadata_2025_split huggingface dataset:
Single Frequency Microwave Dielectric Heating and Measuring
Authors: Tian B.Q. , Tinga W.R. , Xi W. 
Published: March 2011

ABSTRACTTraditional microwave heating and measuring are mostly conducted using two different channels, i.e., a single frequency high power channel for heating and a sweeping frequency low power channel for measuring. Here, a different single frequency system is discussed, by which heating and measuring are conducted simultaneously using one high power source. The theoretical basis emphasizing Q determination at a single frequency is presented. A re-entrant resonator serves as the applicator. Without the normally required swept frequency channel, the experimental system is greatly simplified.
Steady State Temperature Profile in a Sphere Heated by Microwaves
Authors: Barmatz M. , Jackson H.W. 
Published: March 2011

ABSTRACTA new theory has been developed to calculate the microwave absorption and resultant temperature profile within a sphere positioned in a single mode rectangular cavity. This theory is an extension of a total absorption model based on Mie scattering results. Temperature profiles have been computed for alumina spheres at the center of a rectangular cavity excited in the TM354 mode. Parametric studies reveal significant structure in those profiles under special conditions that are associated with electromagnetic resonances inside the spheres. Anomalous behavior similar to thermal runaway occurs at moderate temperatures when there is enhanced absorption associated with resonant conditions in the sphere.
Fullerenes Doped with Thallium Alloys
Authors: Kraus M. , Baenitz M. , GÄrtner S. , Vieth H.M. , Werner H. , SchlÖgl R. , KrÄtschmer W. , Kanowski M. , Thommen V. , GÜntherodt H.-J. , LÜders K. 
Published: March 2011

ABSTRACTPrompted by earlier work showing that graphite intercalation compounds form superconducting ternary compounds in which thallium plays an important role C60 has been doped with Tl-alloys. Results of dc-magnetization, ac-susceptibility, X-ray analysis and NMR investigations will be presented.
Neutron Spectroscopy of Superconducting Fullerides
Authors: Prassides Kosmas , Christides Christos , Tomkinson John , Rosseinsky Matthew J. , Murphy D. W. , Haddon Robert C. 
Published: March 2011

ABSTRACTThe phonon spectra of pristine fullerene, superconducting K3C60 and saturation-doped Rb6C60 measured by inelastic neutron scatteringin the energy range 2.5 - 200 meV at low temperatures reveal substantial broadening of five-fold degenerate Hg intramolecular vibrational modes both in the low-energy radial and the high-energy tangential part of the spectrum. This provides strong evidence for a traditional phonon-mediated mechanism of superconductivity in the fullerides but with an electron-phonon coupling strength distributed over a wide range of energies (33-195 meV) as a result of the finite curvature of the fullerene spherical cage.
Growth and Characterization of InxGa1−xP(x≤0.38) on GaP(1OO) with a Linearly Graded Buffer Layer by Gas-Source Molecular Beam Epitaxy
Authors: Chin T. P. , Chang J. C. P. , Kavanagh K. L. , Tu C. W. , Kirchner P. D. , Woodall J. M. 
Published: March 2011

ABSTRACTInxGa1−xP(x>0.27) grown on a GaP substrate has a large direct-bandgap, which is suitable for yellow light emission on a transparent substrate. Because of the large lattice mismatch, usually a thick (10–20 μm) graded buffer layer was required to reduce the threading dislocation density. In this work we report that a thin (1.2 μm for x≃0.35), linearly graded buffer layer can filter out dislocations effectively. The structures were grown by gas-source molecular beam epitaxy. Reflection high-energy electron diffraction (RHEED) intensity oscillations and X-ray double-crystal diffraction were used to control and determine the composition, respectively. Threading dislocations are well confined in the buffer layer, as shown under transmission electron microscopy. Dislocation loops injected into the substrate were observed, similar to those observed in the Six Ge1−x/Si system. X-ray analysis also shows that the 3% mismatched buffer layer is fully relaxed. This relaxed buffer layer then can serve as a substrate for further growth. Homojunction and heterojunction light emitting diodes were fabricated to demonstrate the material quality.
Carbon Incorporation in Gaas grown by UHVCVD Using Trimethylgallium and Arsine
Authors: Park Seong-Ju , Ro Jeong-Rae , Sim Jae-Ki , Lee El-Hang 
Published: March 2011

ABSTRACTWe present results of a study on the effect of unprecracked arsine(AsH3) and trimethylgallium(TMGa) on carbon incorporation in UHVCVD(Ultra High Vacuum Chemical Vapor Deposition) grown GaAs epilayers on GaAs(100). Three distinct temperature-dependent regions of growth rates were identified as growth temperature was increased from 570 to 690°C. The growth rates were also strongly dependent on V/III ratio in a range of 5 to 30, which clearly indicates that the growth rate is determined by the amount of arsenic adsorbed on the surface at low V/III ratio and adsorption of TMGa or decomposition process at high V/III ratio. Hall concentration measurements and low temperature photoluminescence data show that the films are all p-type and their impurity concentrations are reduced by two orders of magnitude compared to those of epilayers grown by CBE(Chemical Beam Epitaxy) which employs TMGa and arsenic(precracked arsines) as source materials. Our results indicate that the hydrogen atoms dissociated from adsorbed arsine may remove hydrocarbon species resulting in a significant drop in hole concentration.
Time-Resolved Reflectivity Study of Solid-Phase Epitaxial Regrowth in Relaxed and Strained Si1−xGex Epilayers
Authors: Haynes T. E. , Lee C. , Jones K. S. 
Published: March 2011

ABSTRACTThe rate of solid-phase epitaxial regrowth has been studied using time-resolved reflectivity in three different types of SiGe/Si epilayers amorphized by ion implantation. In two of these cases, the alloy epilayer contained either 12% or 20% Ge, and the amorphization depth was greater than the thickness (2000 Å) of the SiGe alloy layer. Time-resolved reflectivity measurements showed that the rate of regrowth was not constant in these two cases, but first decreased after passing the SiGe/Si interface, and then increased. The minimum regrowth rate occurred closer to the SiGe/Si interface in the epilayers with the larger Ge atomic fraction. In the third type of sample, the alloy epilayer thickness was ∼7μm, so that the initial epilayer (15% Ge) had the lattice constant of the bulk alloy. Furthermore, amorphization and regrowth occurred entirely within the relaxed alloy layer. In this case, the regrowth rate was constant. The composition dependence of the regrowth-rate transient in the strained layers is discussed in the context of a ‘critical-thickness’ model of strain relaxation.
Activation of N-Acceptor in MOCVD-ZnSe by Excimer Laser Annealing
Authors: Padmapani Nallan , Neumark G. F. , Taskar N. , Dorman D. 
Published: March 2011

ABSTRACTThe recent success in obtaining blue-green diode lasers using ZnSe-based heterostructures has been mainly due to the successful p-doping of ZnSe using a N plasma source in an MBE system. P-type ZnSe can also be grown by MOCVD, using NH3 as the dopant source. Dopant concentrations of up to 1018 cm−3 have been obtained but net acceptor concentrations are in the range of only about 1015 cm−3 Activation of the remaining N has been achieved to some extent (NA -ND∼3*1016cm−3 ) by rapid thermal annealing. However, this has had limited success. We have used fast surface annealing by an excimer laser to activate the N. We have observed an increase in the ratio of Acceptor Bound Exciton peak intensity to Free Exciton peak intensity on annealing and this effect increases as we increase the laser power density from 10 to 30 MW/cm2. Electrical measurements ( C-V ) give a net acceptor concentration of ∼2*1016 cm−3 and thus confirm the increase in carrier concentration after annealing.
Characterization of nGaAs-Au Schottky Diodes as Grating Coupled Photodetectors
Authors: Krishnaswami Kannan , Karakashian A. S. , Wong C. 
Published: March 2011

ABSTRACTUsing holography and wet chemical etching, a grating of period 450nm and depth of 15nm was fabricated on a n-type GaAs substrate having a doping of 1016 cm−3. A 30 nm layer of Au was deposited on the substrate forming a Schottky contact. The ohmic back contact is an alloy of Ni, Au and Ge. These devices were optically and electrically characterized.Optical characterization was done using a polarized 632.8 nm HeNe laser. Reflectivity measurements for complete angular scans with output currents were determined. It was observed that as reflectivity dropped to a minimum, at a specific incident angle, the output current peaked. This was attributed to excitation of surface plasma oscillations in the grating, allowing greater photon absorption in the depletion region. This was observed only when the incident electric field was p-polarized and normal to the orientation of the grating, thus satisfying the surface plasma resonance conditions.Under the above conditions, it was observed that in a grating coupled photodetector a higher quantum efficiency can be achieved.
Method For Producing Prealloyed Chromium Carbide/Nickel/Chromium Powders and Properties of Coatings Created Therefrom
Authors: Houck David L. , Cheney Richard F. 
Published: March 2011

ABSTRACTA unique process for producing powder whose individual particles contain both chromium carbide and nickel/chromium is discussed. This process involves agglomeration of fine chromium carbide with nickel/ chromium-bearing materials using a proprietary binder system. The agglomerates are subsequently sintered, melted in a plasma flame, and sized. This powder does not exhibit the segregation and inhomogeneity problems associated with conventional mechanical blends of chromium carbide and Nichrome powders. Jet Kote* coatings created from the prealloyed powders have uniform microstructures, high hardnesses, and wear characteristics superior to those of plasma-sprayed coatings from the conventional blends.
Diagnostics Under Thermal Plasma Conditions
Authors: Fauchais P. , Coudert J.F. , Vardelle A. , Vardelle M. , Lesinski J. 
Published: March 2011

ABSTRACTA number of diagnostics problems in the low temperature plasma generators have been analysed with special attention to the plasma spraying process, and a general approach to these problems has been proposed. The advantages, difficulties and limitations of optical nonintrusive methods have been discussed. Examples based on authors experience during last few years, are given.
Excitation of the 4F-4F Emission of Donor-Type Rare-Earth Centers Through Donor-Acceptor Pair States (ZNS:TM)
Authors: LÖbe K. , Boyn R. , Zimmermann H. 
Published: March 2011

ABSTRACTEnergy transfer from donor-acceptor pair states is known to be an efficient excitation channel for 4f-4f emission, especially if the rare-earth centers themselves are the relevant donors. Information on this type of mechanism can be obtained in the case when it is possible to observe, parallel to the 4f-4f emission, luminescence arising from radiative deexcitation of the pairs.We have found these two kinds of emission, under electron-beam excitation, in ZnS:Tm crystals which, according to earlier site-selective studies performed by us, contain predominantly donor-type rare-earth centers. Characteristic differences between the two kinds of emission are found in the dependence of intensities on pumping rate; these arise from partial blocking of the energy transfer due to depopulation of the 4f ground levels. By quantitative studies of the correlation between those intensities we demonstrate that the same types of initial states are involved in the energy transfer and the pair transitions.
Sub-Nanometer Microscopy the Easy Way: An Underutilzed Tool for Reliability Assurance
Authors: Hamilton Doug , Colvard C. 
Published: March 2011

AbstractScanning electron microscopy (SEM) is a frequently used tool for establishing reliability where potential causes of failure are related to structural aspects that show up on a submicron scale. Conventional SEMs, however, even those equipped with field emission sources, can provide high-quality photomicrographs only up to a magnification of about 100,000×. For many purposes greater resolution (several nanometers or below) is required, in which case the usual alternative is to turn to transmission electron microscopy (TEM), in spite of the laborious sample preparation required and limited plan-view images obtained. We describe here an underutilized alternative to TEM for many applications. The in-lens field emission SEM (ILFESEM) can provide pictures above 500,000× magnification with sub-nanometer resolution, with the simple sample preparation and surface viewing advantages of the SEM. Magnification in this range is necessary to verify modern day tolerances on surface morphology and roughness, oxide and thin film structure, thickness, and step coverage, and pore sizes in adhesion layers or diffusion membranes.
Analysis of Thermal Stress Induced Void Growth During Thermal Cycling
Authors: Brown D.D. , Korhonen M.A. , Børgesen P. , Li C.-Y. 
Published: March 2011

AbstractRecent work in thermal stress induced voiding in passivated lines has focussed on the isothermal, quasi-steady state growth of existing voids. In this work, the transient growth and shrinkage of voids during the thermal cycling of narrow, passivated lines was studied. Analysis of experimental data for passivated lines demonstrates the quick buildup and evolution of a backstress at the grain boundary during heating and cooling. This backstress greatly reduces the driving force for void growth at higher temperatures and must be accounted for in stress induced void growth models for the case of appreciably varying temperatures in short time scales.
Incorporation of Nitrogen into Oxynitride Dielectric Through Thermal Nitridation of Silicon
Authors: Maiti Bikas , Hao Ming-Yin , Lee Jack C. 
Published: March 2011

AbstractA novel oxynitride processing scheme has been developed to provide improved performance over thermal oxides. These dielectrics were formed by nitridation of bare silicon wafers followed by deposition of low pressure chemical vapor deposited (LPCVD) oxides at 450°C and reoxidation at 900°C. This novel process provides a good control of dielectric thickness and the amount of nitrogen incorporated at the silicon/silicon dioxide interface. It also reduces the incorporation of the hydrogen-related electron traps in the bulk of the dielectric. Excessive electron trapping is a potential problem of the nitrided oxides. These oxynitride dielectrics referred to as “LPCVD Oxynitride” or “Reoxidized CVD Oxide on Nitrided Silicon” also exhibit relatively large charge-to-breakdown (QBD), considerable reduction in electron trapping and interface state (Dit) generation. The dielectric integrity of these LPCVD Oxynitride was also compared to other oxynitrides which were formed by oxidation of nitrided silicon (“Oxidized-Nitrided Silicon Dielectric”). It was found that the electrical characteristics of the oxidized nitrided silicon dielectrics are inferior compared to the LPCVD oxynitrides (e.g., QBD is substantially lower). Furthermore, for the case of LPCVD oxynitrides, higher nitridation temperatures leads to larger QBD. These results might be explained by the model in which microdefects are incorporated into the oxide when the silicon is consumed as in the cases of oxidized-nitrided silicon dielectrics.
Effect of Laminates and Alloy Additions on Electromigration in AI Interconnects
Authors: Atakov E. M. , Shepela A. , Miner B. 
Published: March 2011

AbstractThe effect of solutes and refractory-metal laminates on the electromigration resistance of Al films is consistent with the effect of those variables on Al grain growth during deposition and/or post-patterning anneal.
Effect of Post-Annealing on Electrical Properties of Ta2O5 Thin Film Deposited by Pecvd Using TaCl5 and N2O
Authors: Park Jong-Wan , Han S.W. , Moon H.S. , Lee J.S. 
Published: March 2011

AbstractThe effect of high temperature annealing, in the temperature range of 600∼900°C on the electrical properties and microstructure of tantalum pentoxide (Ta2O5) film deposited by PECVD was studied. The leakage current of the Ta2O5 film annealed at 600°C showed a minimum value in this study. However, it was found that the leakage current in the polycrystalline Ta2O5 film annealed above 800°C was decreased by increasing the annealing temperature. The dielectric constant of the annealed Ta2O5 film was 26 at 600°C, and decreased with the same tendency as leakage current characteristics. TEM and XRD analysis indicated that the microstructure of the Ta2O5 film annealed above 800°C was of ε-Ta2O5 with hexagonal crystal structure. Furthermore, TEM and AES observations revealed that Ta-O-Si transition layers were formed between annealed Ta2O5 layer and Si substrate. The electrical properties of the Ta2O5 films were discussed in terms of interface modification and film densification due to post-annealing
Group III Metal Clusters on (001) III-V Compound Semiconductors
Authors: Puddephatt S. , Lowes T.D. 
Published: March 2011

ABSTRACTThe interaction of group III Metal clusters with the underlying III-V compound semiconductor substrate is examined. Specifically, both In and Ga on InP and GaAs (001) are discussed. Two Methods of obtaining an excess concentration of the group III Metal are treated: thermal decomposition in UHV where preferential group V dissociation and vaporization leaves a supersaturation of metal and Knudsen cell deposition in an MBE system. It is shown that the resulting morphologies for all cases are attributable to significant cluster/substrate interactions.
Pulsed Laser Deposition of Epitaxial (110) Tin Films on (100) Gaas - Processing, Characterization and Modeling
Authors: Zheleva Tsvetanka , Jagannadham K. , Biunno N. , Narayan J. 
Published: March 2011

ABSTRACTEpitaxial (110) titanium nitride films have been grown on (100) GaAs by pulsed laser deposition technique. The film quality has been found to be a strong function of the processing parameters. The films have been characterized using four point probe resistivity technique, Raman spectroscopy, X-ray diffraction analysis, and transmission electron Microscopy. Single crystal films were obtained at the deposition temperature 450° C and the room temperature resistivity was found to be 49.7 ΜΩ-cm. The epitaxial orientation relationship of the TiN films with the substrate is given by [001]TiN//[110] GaAs and [īlO]TiN// [līO]GaAs. Modeling studies have been performed to characterize the domain epitaxial growth in these large mismatch systems.
Energy Minimization During Epitaxial Grain Growth: Strain VS. Interfacial Energy
Authors: Floro J. A. , Carel R. , Thompson C. V. 
Published: March 2011

ABSTRACTWe have investigated Epitaxial Grain Growth (EGG) in polycrystalline Ag films on Ni (001) substrates. EGG is driven by minimization of crystallographically anisotropie free energies such as the film/substrate interfacial energy and the film strain. Under some conditions EGG results in the preferred growth of the (111) epitaxial orientations that are predicted to minimize the interfacial energy. However, when Ag films are deposited on Ni (001) at low temperature, EGG experiments consistently find that (111) oriented grains are consumed by grains with (001) orientations predicted to have much higher interface and surface energy. The large elastic anisotropy of Ag can account for this discrepancy. The film thickness and the deposition temperature (relative to the grain growth temperature) determine whether strain energy or interface energy minimization dominates orientation evolution during grain growth.
Structural Transitions in Titanium-Aluminum Thin Film Multilayers
Authors: Ahuja Rajiv , Fraser Hamish L. 
Published: March 2011

ABSTRACTThis paper presents the results of a detailed study of titanium - aluminum thin film multilayers fabricated using UHV Magnetron sputtering. Transmission electron Microscopy (TEM) techniques have been used to characterize the structure of these multilayers and to study the various structural transitions as a function of the composition modulation wavelength (CMW). Evidence is presented which indicates the existence of a titanium based fcc structure in these films, below a critical CMW. At even smaller values of CMW, both the Ti and Al layers adopt the hep structure and are coherent with each other. The evolution of thin film microstructure has been studied using high resolution TEM (HRTEM) and an attempt is made to rationalize the stability of different phases based on the energetics of atomic stacking.
AB Initio Study of the Ge Adsorption and Diffusion on Si (100) Surface
Authors: Milman V. , Pennycook S.J. , Jesson D.E. , Payne M.C. , Stich I. 
Published: March 2011

ABSTRACTWe identify the binding sites for adsorption of a single Ge atom on the Si (100) surface using ab initio total energy calculations. The calculated diffusion barriers are in excellent agreement with experimental estimates. Using a large supercell we resolve the controversy regarding the binding geometry and migration path for the adatom, and investigate the influence of the adatom on the buckling of Si dimers. The adatom induces a buckling defect that is frequently observed using scanning tunneling Microscopy (STM); therefore the study of single adatoms may be experimentally accessible.
Nucleation of Dislocations in SIGe Layers
Authors: Mooney P.M. , Legoues F.K. , Chu J.O. 
Published: March 2011

AbstractWe present an x-ray diffraction study of the variation of the tilt angle between a relaxed Si1−xGex epitaxial layer and the Si (001) substrate. Such measurements provide the basis for a new method to determine the nucleation activation energy of misfit dislocations. We show that the nucleation activation energy for 60° dislocations in the case of the multiplication mechanism observed in graded SiGe layers grown by UHV-CVD at low temperature is 4 eV.
Computer Simulation of Creation of Dislocations in Copper Small Crystals
Authors: Tanaka H. , Doyama Masao 
Published: March 2011

AbstractDislocations were created near the center of the surface (101) of copper small crystals whose surfaces are (111), (111), (101), (101), (121), and (121) by use of n-body atom potentials and molecular dynamics. At first, a Heidenreich-Shockley partial dislocation was created., As the partial dislocation proceeds, the partial dislocation and the surface was connected with a stacking fault until the next Heidenreich-Shockley partial dislocation was created at the surface.Just before the creation of a partial dislocation the stress was the highest.
Second Phases and Impurity Segregations in MgO- and NiO-CO-Doped Alumina
Authors: Park K. , Sung C. , Vasilos T. 
Published: March 2011

AbstractThe microstructural and chemical characteristics of the segregated particles, Ni-(Mg)-Al spinel phases, and K-ß’’’ alumina precipitates in fine-grained alumina co-doped with 0.15 wt % of MgO and 0.10 wt % of NiO were studied using analytical transmission electron microscopy. The segregated Ni particles and second phases were generally found at triple junctions or on grain boundaries. The K-ß’’’ alumina precipitates were found to contain occasionally a high density of stacking faults. These microstructural observations point out the location of the dopants and impurities during the sintering process.