bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prediction of Residual Stresses in an Autofrettaged Thick–Walled Cylinder
Authors: Chen Peter C. T. 
Published: March 2011

ABSTRACTMost of the earlier results for residual stresses are based on the assumption of elastic unloading. In this paper, the prediction of residual stresses for the case of reverse yielding including the combined Bauschinger and hardening effect will be reported for an autofrettaged thick-walled cylinder. The Bauschinger effect factor is varying as a function of overstrain. The strain-hardening effect is considered with different parameters used for loading and unloading process. The new results indicate that the influence of the combined Bauschinger and hardening effect on residual stress distribution is significant.
Stress Analysis of a Beveled Diamond Anvil
Authors: Bruno M. S. , Dunn K. J. 
Published: March 2011

ABSTRACTA finite element stress analysis has been performed on a brilliant cut high pressure diamond anvil. The analysis includes the presence of a metal gasket. A perfectly cohesive interface is assumed to exist between the diamond and metal. Different configurations of the anvil face were studied. The stress distribution resulting from various beveled angles has been analyzed. It has been found that for a flat anvil, with a center normal pressure of about 210 kbar, an octahedral shearing stress of about 90 kbar is present near the center and monotonically increases radially to about 208 kbar along the outer edge. When the anvil surface is beveled, the octahedral shearing stress at the outer corner decreases significantly. The optimum beveled angle necessary to minimize these stresses seems to lie in the neighborhood of 15 degrees. The assumptions made and other stress considerations are discussed.
Predicting Catastrophic OD Initiated Fatigue Failure of Thick-Walled Cylinders Using Low Cycle Fatigue Data
Authors: Kapp Joseph A. 
Published: March 2011

ABSTRACTA procedure is presented to predict fatigue failure of thick-walled cylinders containing discontinuities at the OD. Both crack initiation life and crack growth are considered. The elastic-plastic strains at an OD discontinuity are estimated using an elastic analysis and stress concentration factors. The strain estimates are then used in conjunction with low cycle fatigue data to determine the initiation life. Crack growth life is estimated by integration of a power law relationship. The results obtained by using this analysis method compared to measured fatigue life data for several OD initiated failures in thick-walled cylinders agrees to within about 10 percent.
High Pressure Sealing Characteristics of Metallic Sleeve Seals
Authors: Dean T.J. , Elligsen R.A. , Mohaupt U.H. 
Published: March 2011

ABSTRACTClose tolerance metallic sleeves may be used as seals for reciprocating pumps or intensifiers operating at pressures up to 700 MPa. Seals of this type may be designed to provide a low friction sealing action which minimizes the usual wear problems. This paper presents the high pressure performance characteristics of such seals and examines the influence of parameters such as seal geometry, initial clearance, working pressure and fluid viscosity and temperature on leakage rates. Experimental results are compared with theoretical data generated using a computer model.
Very High Pressure Generation at the Deep Sea
Authors: Suito Kaichi , Yasukawa Katsumi 
Published: March 2011

ABSTRACTIn the deep sea, truely hydrostatic pressure is produced in a very large area. This pressure may be used as natural resources. By utilizing these resources, very high pressures can be generated using a 6–8 type split-sphere high pressure apparatus. A preliminary experiment to generate very high pressure was undertaken in the deep sea at a depth of about 1000 m. Pressures of about 8.5 GPa were generated in the central part of the high pressure apparatus.
A Method to Determine the Pressure Dependent Distortion of a Simple Piston Gage Based on Dimensional Metrology
Authors: Welch B.E. , Bean Vern E. 
Published: March 2011

ABSTRACTElastic distortion of the piston and cylinder is the leading cause of inaccuracy in piston gages at higher pressures. The distortion depends upon the pressure profile between the piston and the cylinder. One possible method of determining the pressure profile is demonstrated.
Compression of CCl4 at High Pressures
Authors: Wood Sharrill D. , Bean Vern E. 
Published: March 2011

ABSTRACTThe compression of carbon tetrachloride has been measured along twelve isotherms covering a pressure range of 0.1 to 200 MPa and a temperature range of 254 to 298 K. Volume changes were measured with an automated capacitance bridge–one side of the bellows containing the sample serving as one plate of the capacitor. Data were obtained in the liquid, face-centered cubic (fcc), and rhombohedral phases, during melting, during freezing into the fcc phase and during the fcc to rhombohedral phase change. Premelting behavior was observed for both solids. The disappearance of the fcc phase at approximately 273 K and the existence of dual melting curves for the fcc and rhombohedral phases were reaffirmed.
Molecular Thermodynamics of Supercritical Fluid Mixtures
Authors: Eckert Charles A. 
Published: March 2011

ABSTRACTSupercritical fluid extraction uses a dense gas as a solvent at a temperature only slightly above its critical temperature and a pressure of a few hundred bars. The process offers the advantages of both conventional distillation and solvent extraction, and permits the facile achievement of difficult separations by highly selective absorption and desorption of various solutes. A valid thermodynamic model is essential for the rational design of such processes. We have made extensive solubility measurements at pressures to about half a kilobar, and we interpret the results in terms of perturbed hard-sphere equations of state. In this, we characterize solution nonidealities in terms of enhancement factors, which are often in the range of 103−108. Even better information about the specific solvent-solute interactions are available from measurements of partial molal volumes in supercritical solutions. These are very difficult measurements, as the effects are most pronounced precisely where the solvent compressibility is greatest, and accurate data are possible only because of the advent of the high-pressure vibrating tube densitometer, which converts density determinations to highly accurate frequency measurements for determinations to a precision of ±0.0001 g/cc. The solute partial molal volumes are many liters negative in the critical region, and these data are interpreted in terms of various equations of state.
Single-Pulse Coherent Raman Spectroscopy in Shock-Compressed Benzene
Authors: Moore D. S. , Schmidt S. C. , Schiferl D. , Shaner J. W. 
Published: March 2011

ABSTRACTSingle-pulse backwards stimulated Raman and reflected broadband coherent anti-Stokes Raman spectroscopy (BSRS and RBBCARS) have been used to measure the vibrational frequency shifts of the 992 cm−1 ring-stretching mode of liquid benzene shock-compressed to pressures up to 1.2 GPa. The resulting shifts of ∼7.5 cm−1/GPa in the dynamic experiments are compared to spontaneous Raman scattering measurements of heated samples compressed in a diamond-anvil cell. RBBCARS was used to simultaneously measure the ring-stretching mode vibrational frequencies of liquid benzene / liquid perdeuterobenzene mixtures shock-compressed to pressures up to 1.53 GPa. Additional experiments that demonstrate the difficulty of using polarization sensitive coherent Raman techniques, such as Raman-induced Kerr effect spectroscopy (RIKES), in shock-compressed samples are described.
Growth of GexSi1−X/Si Alloys on Si (100), (110) and (111) Surfaces
Authors: Hull R. , Bean J. C. , Peticolas L. , Xie Y. H. , Hsieh Y. F. 
Published: March 2011

ABSTRACTWe compare and contrast GexSi1−x alloys grown on Si (100), (110) and (111) surfaces. The geometry of interfacial misfit dislocations are observed to be different on these three surfaces, as the intersections of available ♣111} glide planes are of different symmetries for the different interfaces. In addition, angular factors resolving the applied and line tension stresses onto misfit dislocations vary over the different surfaces, producing different effective stresses for identical layer thicknesses, compositions and microstructures. Finally, markedly different dislocation microstructures are observed on the different surfaces, as geometrical considerations show that partial dislocations may separately propagate on the (110) and (111) surfaces, in contrast to the (100) surface.
Measurement of Valence Band Offset in Strained GexSi1−x/Si Heterojunctions
Authors: Khorram S. , Chern C. H. , Wang K. L. 
Published: March 2011

ABSTRACTThe valence band discontinuity ΔEV in the coherently strained GexSi1−x/Si heterostruc-ture is determined using I-V-T measurement. The electrical measurements of the band discontinuity of the pseudomorphic layers are difficult due to the thin layer imposed by the strain. Recently, low temperature growth of thick layer (>100 nm) of coherently strained GexSi1−x on Si has been achieved and thus made it possible for an accurate electrical measurement of band offset. The results obtained are in good agreement with the theoretical calculations by pseudopotential method.
Low Threading Dislocation Densities in Thick, Relaxed Si1−xGex Buffer Layers
Authors: Tuppen C. G. , Gibbings C. J. , Hockly M. 
Published: March 2011

ABSTRACTA series of relaxed Si1−xGex alloy layers with germanium contents up to 70% has been deposited on silicon. Although direct deposition ot these highly mismatched layers on silicon gave dislocation densities of 109-1010cm2 and poor morphology, it was found that the use of a linear grade enabled completely relaxed Si.3Ge.7 layers with defect densities of ∼3.105cm−2 to be obtained. However, if the grading was too rapid the dislocation density was much higher. The role of dislocation nucleation and propagation in determining the required thickness of graded layer is discussed.
Intensity Modulation of Glancing Angle X-Ray Diffraction Spectra of GexSi1−x/Si Superlattices
Authors: Wang Xun , Zhou G. L. , Sheng C. , Yu M. R. 
Published: March 2011

ABSTRACTThe glancing angle x-ray diffraction spectra of GexSi1−x/Si superlattices grown by MBE under different temperatures are investigated. Three different types of the intensity distributions of diffraction peaks are observed, which are believed to be corresponded with different situations of interfaces. If all the interfaces in superlattice structure are highly flat, up to 17 orders diffraction peaks are identified with their intensities modulated by a periodical envelope function, otherwise the distribution of diffraction intensities follows simply a decaying function. A quantitative analysis using computer simulation based on the modified Bragg's law and the optical multilayer theory is used to derive the structural parameters including the thicknesses of Si and GexSi1−x layers, superlattice period, Ge content x and the degree of interfacial roughness.
Temperature Dependence of Critical Thickness for Two Dimensional Growth of GexSi1−x on Si Substrate
Authors: Wang Xun , Zhou G. L. , Zhou T. C. , Sheng C. , Yu M. R. 
Published: March 2011

ABSTRACTFor obtaining good structural perfection, the molecular beam epitaxial (MBE) growth of GexSi1−x on Si substrate should not only be kept in the pseudomorphic form but also in layer-by-layer growth stage. We found that the two dimensional layer-by-layer growth of GexSi1−x on Si could persist to a certain deposition thickness, beyond that the transition to islanding growth occurs. The transition thickness is significantly dependent on the growth temperature and germanium content, and is always smaller than the critical thickness of pseudomorphic growth. In order to obtain good crystalline quality in growing GexSi1−x superlattices on Si substrates, the thickness of GexSi1−x layers should be controlled below the transition thickness and lower growth temperature is favorable.
High Definition Mesa Growth by Silicon MBE
Authors: Hammerl E. , Wittmann F. , Messarosch J. , Eisele I. , Huber V. , Oppolzer H. 
Published: March 2011

ABSTRACTA novel epitaxial growth method for fabricating mesa patterns on a micrometer scale has been investigated. Electrical devices have been prepared employing this technique and their characteristics are in good agreement with those of mesa etched devices.
Residual Strain and Defect Analysis in as Grown and Annealed SiGe Layers
Authors: Powell A. R. , Kubiak R. A. , Whall T. E. , Parker E. H. C. , Bowen D. K. 
Published: March 2011

ABSTRACTIn this paper we address the problem of producing SiGe buffer layers of acceptable quality for the growth of symmetrically strained SiGe structures. Initially we consider SiGe layers grown to well beyond the metastable critical thickness and examine the degree of residual strain both as - grown and post anneal. The defect levels in metastable SiGe layers following high temperature anneal were also studied. A buffer layer was grown consisting of stacked metastable SiGe layers each of which is annealed in situ prior to the growth of the next layer and terminating with a 0.45 SiGe alloy. This produces nearly fully relaxed 1.15pim thick structures with threading dislocation densities of 4 × 106cm−2. Limited area growth on Si suggests that elastically relaxed material free of both threading and misfit dislocations can be produced.
Photoreflectance and Resonant Raman Scattering in Short Period Si/Ge Superlattices on Ge (001) and Si (001)
Authors: Menczigar U. , Eberl K. , Abstreiter G. 
Published: March 2011

ABSTRACTShort period Si/Ge superlattices have been grown on Ge (001) and Si (001) substrates by molecular beam epitaxy. The optical properties of the superlattices have been studied with photoreflectance. (PR) and resonant Raman scattering (RRS). With PR we are able to observe new, structural induced transitions for all superlattices which are related to E0-and E1-like gaps. The analysis of PR spectra is complicated by an optical etalon effect if the samples are sufficently thick. The E1-like transitions in the range between 1.9eV and 2.7eV are also studied with RRS. Due to the confinement of the optical phonons in the Ge and Si layers RRS is able to probe the bandstructure in each layer seperately. Localized electronic states in the Ge layers can be observed with RRS for a Si4Ge18 superlattice and are compared with PR measurements.
The Extraction of Minority Carrier Lifetime from the Current-Voltage Characteristics of Si/Si1−xGex Devices
Authors: Ghani T. , Hoyt J. L. , Noble D. B. , Gibbons J. F. , Turner J. E. , Kamins T. I. 
Published: March 2011

ABSTRACTThe extraction of recombination lifetime from the current-vol tage characteristics of diode structures containing Si1−xGex strained layers is discussed. Electrical measurements are used in conjunction with computer simulations to extract minority carrier lifetime in Si1−xGex layers with various oxygen concentrations. The minority carrier lifetime in Si1−xGex increases from several psec at an oxygen concentration of 2×1020 cm−3, to greater than 0.5 μs at concentrations below 3×1017 cm−3. The structures are analyzed for sensitivity of the current characteristics to Si1−xGex minority carrier lifetime. Calculations predict that the maximum lifetime which can be extracted from such structures is greater than 100 μsec. However, due to limitations imposed by perimeter currents, the maximum lifetime which can be extracted from our diode structures is on the order of 3 μsec. Maximizing area to perimeter ratio of the diode structures and moving the Si1−xGex-SiO2 interface away from the active device region is required in order to increase the maximum extracted lifetime from such structures.
Si/Si1−xGex p-Channel Mosfets Fabricated Using a Gate Quality Dielectric Process
Authors: Kesan V. P. , Subbanna S. , Tejwani M. J. , Restle P. J. , Iyer S. S. 
Published: March 2011

ABSTRACTThe use of Si1−xGex alloys for p-channel high transconductance MOSFETs requires a high quality dielectric system. Direct oxidation of Si1−xGex alloys or even low temperature deposition of SiO2 directly on Si1−xGex results in a very high interface state density. We show that low interface state densities (below 1011 eV−1cm−2) can be obtained using both thermal and PECVD oxides through the use of a thin (6–8 nm) Si cap between the oxide and the Si1-xGex layer. The Si cap layer leads to a sequential turn-on of the Si1−xGex channel and the Si cap channel, as clearly observed in low temperature C-V curves. We show that this dual channel structure can be designed to suppress the parasitic Si cap channel. High quality, fully isolated Si1−xGex p-channel MOSFETs have been fabricated in an integrable, low Dt process using both thermal or PECVD gate oxides and selective UHV/CVD for the Si/ Si1−xGex channels. We show that optimally designed Si/Si1−xGex MOSFETs exhibit up to 70% higher transconductance at 300K than control Si devices fabricated on n-doped 1017/cm3 Si substrates. Si/Si1−xGex p-channel MOSFETs with thermal and PECVD gate oxides show comparable device characteristics.
Integrated Rib Waveguide-Photodetector Using Si/Si1−xGex Multiple Quantum Wells for Long Wavelenghts
Authors: Kesan V. P. , May P. G. , Treyz G. V. , Bassous E. , Iyer S. S. , Halbout J. -M. 
Published: March 2011

ABSTRACTWe have investigated the structural, electrical, and optical quality of epitaxial Si and Si1−xGex films grown by MBE on SIMOX (Separation by IMplanted OXygen) silicon substrates. Epitaxial films grown on these SOI substrates have been characterized using planar and cross-sectional TEM, high resolution X-ray diffraction, SIMS, and Seeco chemical etching to delineate defects. We have fabricated Si/SiGe P-i-N photodetectors integrated with Si waveguides on SOI for long wavelength applications. Low reverse leakage current densities were seen in these device structures. The photodetector exhibited an internal quantum efficiency of 50% at 1.1 μm with a frequency response bandwidth of 2 GHz.
Equipment for Monitoring and Controlling Rheed-Oscillations
Authors: Larsson M. , Björklund L. -E. , Hansson G. V. 
Published: March 2011

ABSTRACTA Light Oscillation Control Unit System (LOCUS) has been developed for the purpose of monitoring Reflexion High Energy Electron Diffraction (RHEED) oscillations and to use the oscillations to control the crystal growth with single atomic layer resolution. The system can be used for phase-locked epitaxy, i.e., shutters controlling the growth are actuated when monolayers are completed. To reduce the usual damping of the RHEED-oscillations, the system can also use the method of synchronization of nucleation, i.e., periodically varying the surface supersaturation by changing the substrate surface temperature during each oscillation. Four shutters can be operated automatically and the superlattice composition can be chosen in a number of different ways. LOCUS gives fast response on intensity oscillation maxima and minima beyond a programmable discrimination level. Relevant crystal growth parameters can be changed during the run of the program, which implies that even quasi-periodic superlattices can be grown. There is also a possibility to switch from automatic to manual control. The shutters and substrate heater have been designed to reduce the influence of shifts of the diffraction pattern as the growth conditions are changed.
Growth of CoSi2 on CaF2/Si (111) Heterostructures
Authors: Adamski C. , Schäffer C. 
Published: March 2011

ABSTRACTIn order to produce an epitaxial metal/insulator/semiconductor structure we investigated the growth of CoSi2 on CaF2/Si (111) heterostructures. We demonstrate the possibility to grow epitaxial CoSi2 on CaF2 films by utilization of the template technique. The fabrication of these structures will be presented. The properties of such heterostructures were determined by means of RHEED, LEED, AES, SIMS, RBS and resistivity measurements.
Studies of SiH2Ci2/H2 Gas Phase Chemistry for Selective Thin Film Growth of Crystalline Silicon, c-Si, Using Remote Plasma Enhanced Chemical Vapor Deposition
Authors: Theil J. A. , Lucovsky G. , Hattangady S. V. , Fountain G. G. , Markunas R. J. 
Published: March 2011

ABSTRACTConventional high temperature, >800°C, CVD processes, utilizing SiH2Ci2 promote selective deposition of c-Si onto c-Si, but not on SiO2 surfaces. We show that low temperature, 300°C remote PECVD, with rf-excited He plasmas, and SiH2Ci2 and H2 injected downstream, also selectively deposits c-Si on c-Si and not SiO2 surfaces. This preliminary study employs in-situ mass spectrometry, MS, to determine the species responsible for selective deposition process reaction pathways. These MS studies suggest that species responsible for film deposition are Si-containing fragments of the SiH2Ci2 molecule, e.g., SiH2Ci, SiCi2H, etc., while the species responsible for inhibiting deposition on the SiO2 surfaces are by-products of the break-up of the SiH2Ci2 molecule in the gas phase, e.g., H-atoms, HCI and H2Ci+ ions.
Last Developments in Luminescence of Porous Silicon
Authors: Bsiesy A. , Gaspard F. , Hereino R. , Ugeon M. , Muller F. , Romestain R. , Vial J. C. 
Published: March 2011

ABSTRACTIt is shown that visible photoluminescence and electroluminescence can be obtained from porous silicon layers. Room temperature photoluminescence is readily obtained from as-formed high porosity samples. Light emission at wavelengths as short as 560 nm can be observed after further thinning of the silicon pore walls by dissolution in HF under illumination. Silicon walls can also be thinned by an electrochemical oxidation process, this method allowing to use layers of rather low porosities (65%) which thus gives good mechanical properties to the samples. The thinning of the already very small size crystallites of porous silicon leads to quantum size effects which are at the origin of the light emission far above the band gap of silicon. Photoluminescence decay characteristics suggest that a tunnelling effect could be involved in the recombination mechanism of photogenerated charge carriers. Bright electroluminescence during anodic oxidation of porous silicon has been also evidenced. The influence of the porosity, of the layer thickness and of the anodic current density on the integrated electroluminescence intensity are described in detail.
Aspects of Crystal Quality of Si (100) Films Grown by Molecular Beam Epitaxy
Authors: Ni W. -X. , Henry A. , Ekberg J. O. , Hansson G. V. 
Published: March 2011

ABSTRACTSilicon layers grown by molecular beam epitaxy, using both direct resistive heating and indirect radiant heating of the substrate, have been evaluated by photoluminescence measurements, diode I-V characterization, and chemical etching tests. The results show that large densities of defects could be introduced when resistively heated substrates were experiencing thermo-mechanical stress. Films with good crystal quality were grown using a carefully designed radiant type heater.
Electromigration Lifetime and Step Coverage in Al/Cu/Si Thin Film Conductors
Authors: Kisselgof Larisa , Elliott L. J. , Maziarz J. J. , Lloyd J. R. 
Published: March 2011

ABSTRACTElectromigration-induced failure was investigated in Al/Cu/Si conductor stripes deposited over trenches cut into an oxide layer and compared with those deposited onto flat areas. The results indicate a reduction in lifetime which is proportional to the size of the step to be covered and this reduction is in excess of what is expected from simple current density scaling. In addition, the electromigration performance of conductors deposited over topology did not correlate well with the performance on flat structures.