| Tailoring of Grain Boundary Chemistry for the Development of Highly Creep Resistant Alumina |
29 AUG 97 |
151 pages |
| Authors:
M. P. Harmer; H. M. Chan; J. Rickman; J. Bruley; J. Cho; LEHIGH UNIV BETHLEHEM PA WHITAKER LAB
|
 | Research has demonstrated that the controlled doping of ultra-high purity alumina with small amounts (<1000ppm) of rare earth elements, such as La and Y, dramatically lowers the sintering and creep rate. Due to the large ionic radius of the rare earth elements, rare earth elements have a low solubility in alumina and segregate strongly to the grain boundaries. Chemical composition (STEM) profiles indicate that segregation of Y and La is ... |
|
| Thermoluminescence Radiation Dosimetry Using Transparent Glass Containing Nanocrystalline Phosphor |
12 AUG 1997 |
|
| Authors:
Brian L. Justus; Alan L. Huston; DEPARTMENT OF THE NAVY WASHINGTON DC
|
 | Radiation is detected using a light transparent thermoluminescent dosimeter that comprises a nanocrystalline phosphor dispersed in a light transparent glassy matrix, such as Vycor glass. The dosimeter is placed in an environment in which radiation is present for a period of time. removed from the environment and then heated to emit light the intensity of which is indicative of the radiation dose. The method of the invention is useful for ... |
|
| Diamond Film Deposition on Graphite |
05 AUG 1997 |
|
| Authors:
Mark B. Moran; Karl A. Klemm; Linda F. Johnson; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A continuous, adhering film of polycrystalline diamond is grown on a graphite substrate from diamond crystallite nucleated at a metal layer on the substrate when subjected to a microwave activated plasma of hydrogen and a carbon containing gas. Pyrolytic graphite and cured graphite adhesive are effective and other forms of graphite may be effective. Effective metals are chromium, nickel, and titanium. Diamond nucleation apparently occurs at crystallite of metal carbides ... |
|
| Proceedings of the Ninth International Conference on Molecular Beam Epitaxy Held in Malibu, California on August 5-9, 1996. Part 1, Sections I-VIII |
AUG 97 |
|
| Authors:
Y. C. Kao; CALIFORNIA UNIV LOS ANGELES
|
| In MBE-IX, 265 papers, including 14 invited talks, were selected from 400 abstract submissions. The percentage of papers being selected is the lowest as compared to previous International MBE conferences, indicating strong interest and growth in MBE development. MBE is now of fundamental importance in the creation of advanced new materials and device structures for electronics, optoelectronics, and photonics applications. MBE has progressed to the point that it is now ... |
|
| Proceedings of the Ninth International Conference on Molecular Beam Epitaxy Held in Malibu, California on August 5-9, 1996. Part 2 Sections IX- XVIII |
AUG 97 |
|
| Authors:
Y. C. Kao; CALIFORNIA UNIV LOS ANGELES
|
| In MBE-IX, 265 papers, including 14 invited talks, were selected from 400 abstract submissions. The percentage of papers being selected is the lowest as compared to previous International MBE conferences, indicating strong interest and growth in MBE development. MBE is now of fundamental importance in the creation of advanced new materials and device structures for electronics, optoelectronics, and photonics applications. MBE has progressed to the point that it is now ... |
|
| Numerical Studies of the Physics and Operation of LTG Materials and Devices |
AUG 97 |
31 pages |
| Authors:
Harold L. Grubin; SCIENTIFIC RESEARCH ASSOCIATES INC GLASTONBURY CT
|
| This document summarizes Scientific Research Associates, Inc., (SRA) low temperature material studies carried out under U.S. Air Force Office of Scientific Research (AFOSR) Contract F49620-94-C-0024. The study summarizes a model that was developed that is consistent with present low temperature growth (LTG) experimental studies. SRA's study included one dimensional transient simulations and two dimensional time independent constrained geometric studies. The broad aspects of the study indicate that annealed LTG GaAs ... |
|
| Diamond and Related Materials: International Journal on the Science and Technology of Diamond and Related Materials, Volume 6, No. 10, August 1997 |
AUG 97 |
351 pages |
| Authors:
R. Messier; J. C. Angus; T. R. Anthony; P. K. Bachmann; A. M. Bonnot; ELSEVIER SCIENCE PUBLISHERS LTD BARKING(UNITED KINGDOM)
|
| The first European Conference on Silicon Carbide and Related Materials (ECSCRM 96) was held in Heraklion, Crete, Greece from October 6 to October 9, 1996. This was the first event of a series of biannual conferences addressing wide band gap semiconductors research field and supported by the European Union through the "Euroconferences" action. The next conference will be held in Montpellier, France in 1998. The conference was attended by 140 ... |
|
| MBE Growth and Characterization of GaN/AlN Structures Under Hydrostatic Pressure |
30 JUL 1997 |
7 pages |
| Authors:
R. J. Hauenstein; OKLAHOMA STATE UNIV STILLWATER DEPT OFPHYSICS
|
| We present the results of a series of studies on the optical properties of GaN and AlGaN/GaN heterostructures using a variety of spectroscopic techniques. Strain effects were found to have a strong influence in determining the energies of excitonic transitions. The observations of spectral features associated with the transitions involving the ground and excited exciton states make it possible to directly estimate binding energy for the excitons in GaN. Optical ... |
|
| MBE Growth of GaInAsSb |
23 JUL 1997 |
49 pages |
| Authors:
Shanthi N. Iyer; NORTH CAROLINA AGRICULTURAL AND TECHNICAL STATE UNIV GREENSBORO
|
| Optimum growth conditions for high quality growth of GaAs, GaSb, InSb and GaInAsSb epilayers by Molecular Beam Epitaxy (MBE) on GaAs substrates and homoepitaxial growth of InSb have been determined. A new procedure for expeditious removal of oxide desorption from InSb has been found. InSb epilayers grown on InSb substrate after the above oxide desorption exhibited x-ray rocking curve with full width half maxima of 13 arc-sec, reproducibly. Efforts of ... |
|
| Topical Meeting of the European Optical Society (11th) on Materials for Nonlinear Optics. July 8-12, 1997, Capri (Italy) |
23 JUL 1997 |
215 pages |
| Authors:
LABORATORY FOR PHYSICS AND ELECTRONIC MATERIALS GIF-SUR- YVETTE (FRANCE)
|
| The Final Proceedings for Materials for Nonlinear Optics, 8 July 1997 - 12 July 1997, The Topics covered include: Organic and inorganic single crystals; photorefractive polymers and crystals; theory of optical nonlinearities; molecular engineering; electro-optic polymers; liquid crystalline materials; magnetic materials; nanostructures. |
|
| Study of the Gravity Effect on Ag(109) Gamma-Resonance |
22 JUL 1997 |
8 pages |
| Authors:
Andrey Davydov; TECHNOLOGY TRANSFER SOCIETY CHICAGO IL
|
| This report results from a contract tasking Institute of Theoretical and Experimental Physics as follows: The contractor will obtain data about broadening factor of Ag(109) 88 ksV Mooessbauer gamma-line in the silver single crystal. ANNOTATION: Reprint: tudy of the Gravity Effect on Ag(109) Gamma-Resonance. |
|
| MBE Growth and Characterization of Zincblende GaN and GaN/AlN structures |
15 JUL 1997 |
37 pages |
| Authors:
J. J. Song; R. J. Hauenstein; OKLAHOMA STATE UNIV STILLWATER CENTER FOR LASER RESEARCH
|
| This Program includes fundamental studies of Molecular beam epitaxial (MBE) growth of GaN and its related alloys and heterostructures. In additions, the optical and electrical properties of resultant materials were measured using a variety of spectroscopic techniques. The optical properties concentrated on optically-pumped stimulated emission and laser action in GaN/AlGaN heterostructures. The objective was to better understand the underlying physics of MBE growth, and the optical and electrical properties for ... |
|
| Bi2Te3/Sb2Te3 Superlattice Structures for High-ZT Thermoelectric Cooling Devices |
07 JUL 97 |
9 pages |
| Authors:
Rama Venkatasubramanian; RESEARCH TRIANGLE INST RESEARCH TRIANGLE PARK NC
|
| The goal of this project is to demonstrate factorial improvement in the thermoelectric figure of merit (ZT) with thin film Bi2Te3/Sb2Te3 superlattice (SL) structures compared to state of the art bulk Bi(2-x)Sb(x)Te3 alloys for high performance thermoelectric devices. The motivation for the use of SL structures has been the hypothesis that the atomic size and mass differences at the SL interfaces as well as the periodic SL structure result in ... |
|
| Nanoscale Control of Structure in Electrocrystallized Molecular Materials |
02 JUL 97 |
10 pages |
| Authors:
Michael D. Ward; MINNESOTA UNIV MINNEAPOLIS DEPT OF CHEMICAL ENGINEERING AND MATERIALS SCIENCE
|
| The work performed under this AASERT grant augmented our efforts funded by the original parent grant 'Electrocrystallization of Molecular Solids?' and the recent renewal grant 'Electrocrystallization of Nanostructured Molecular Materials' (the AASERT grant overlapped the renewal of the two grants) . The intention of the AASERT was to devise approaches to the synthesis and modification of electrocrystallized molecular materials aimed at (1) controlling the supramolecular structure of condensed phases through ... |
|
| Electronic Properties of Semimetal-Semiconductor (V/III-V) heterostructures and Devices |
01 JUL 1997 |
10 pages |
| Authors:
Terry Golding; J. H. Miller; C. S. Ting; HOUSTON UNIV TX
|
| The project involved an experimental investigation of the synthesis and the electrical transport properties of semimetal- semiconductor based heterostructures and devices. The structures- consisted of elemental (Sb) semimetals in combination with antimonide based III-V semiconductors (GaSb). The investigation of these novel semimetal-semiconductor heterostructures was motivated by their unique electronic properties and potential device applications, including high conductivity interconnects, double-barrier semimetal-base resonant tunneling transistors, and nanostructures operating in the mesoscopic regime. ... |
|
| Nanocrystalline Processing and Interface Engineering of Si3N4-Based Nanocomposites |
JUL 97 |
7 pages |
| Authors:
Jackie Y. Ying; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF CHEMICAL ENGINEERING
|
| With careful powder handling procedures and processing, the nanocrystalline TiN produced in our novel reactor undergoes tremendous sintering and densification to produce dense (99%) TiN materials at 1400 deg C in a simple, pressureless sintering process. This report outlines the determination of mechanical properties of these materials and contains a benchmark comparison of these properties, and the processing required to achieve them, against other TiN materials reported in the literature. ... |
|
| Digest, IEEE/LEOS 1996 Summer Topical Meetings, August 5-9, 1996, Keystone, Colorado |
JUL 97 |
368 pages |
| Authors:
Edward F. Labuda; LASERS AND ELECTRO-OPTICS SOCIETY (IEEE) PISCATAWAY NJ
|
| The report documents the information presented at the Digest IEEE/ LEOS 1996 Summer Topical Meetings. The conference was held 5-9 August 96 in Keystone, Colorado. The purpose of this symposium was to provide a professional forum for a broad exchange of information and ideals on advanced applications of lasers in materials processing. The symposium was supported from U.S. Army Research Office. In this symposium, topics include the fabrication of silicon ... |
|
| Influence of the Proton Concentration on the Properties of the LiNbO3 and LiTaO3 Crystals |
JUL 97 |
56 pages |
| Authors:
M. P. De Micheli; ECOLE POLYTECHNIQUE PALAISEAU (FRANCE) LAB DE PHYSIQUE DE LA MATIERE CONDENS EE
|
| During this first year, a set of optical waveguides has been realized on LiNbO3, using different PE recipes. They have been characterized optically and rocking curves as well as SIMS measurements have been performed. Some correlation have been evidenced and we are working on more sophisticated details. Influence of the waveguide fabrication process on the nonlinearity and on the poling parameters have also been observed. Experiments are in progress in ... |
|
| Crystallation, X-Ray Structure Determination and Structure-Based Drug Design for Targeted Malarial Enzymes |
JUL 97 |
40 pages |
| Authors:
Lawrence J. DeLucas; ALABAMA UNIV IN BIRMINGHAM
|
| The aim of this project is to identify specific inhibitors of some enzymes of malaria parasite. Inhibitors will be designed based on the high- resolution crystal structure of individual target enzymes. We have already determined the crystal structure of P. falciparum lactate dehydrogenase, a key enzyme in the glycolytic pathway, to high resolution. This structure is currently being used for designing lead inhibitors. We have also purified PFPK- DHPS bifunctional ... |
|
| Functionalized Nanoporous Polymer Membranes with Well-Defined Pore Architectures via Lyotropic Liquid-Crystalline Monomers |
30 JUN 97 |
10 pages |
| Authors:
Douglas L. Gin; CALIFORNIA UNIV BERKELEY DEPT OF CHEMISTRY
|
| Highly ordered, nanoporous polymer membranes were synthesized using polymerizable lyotropic liquid crystals that self-assemble into the inverted hexagonal mesophase as building blocks. The resulting polymer networks contain nanometer-diameter, extended hydrophilic channels that are hexagonally close- packed. Two lyotropic liquid-crystalline monomer platforms have been synthesized. The interchannel separations in the polymerizable materials can be varied in the 30-40 A range by the choice of counterion on the ionic headgroup of the ... |
|
| Anisotropy in Epitaxial Films |
13 JUN 1997 |
7 pages |
| Authors:
C. V. Thompson; R. C. O'Handley; MASSACHUSETTS INST OF TECH CAMBRIDGE CENTER FOR MATERIALS SCIENCE AND ENGINEE RING
|
| Experiments on epitaxial Ni films grown on epitaxial Cu films grown on single crystal (100) Si wafers in a molecular beam epitaxy system modified to make in situ magneto-optic Kerr effect (MOKE) measurements were carried out. Ex situ transmission electron microscopy and wafer curvature measurements were made and it was shown that the onset of misfit accommodation, the decrease in Ni strain with increasing film thickness, and the increase in ... |
|
| Erbium Doped AlGaAs/GaAs Quantum Wells |
02 JUN 97 |
37 pages |
| Authors:
Galna Khitrova; Hyatt M. Gibbs; ARIZONA UNIV TUCSON OPTICAL SCIENCES CENTER
|
| The possibility of enhancing the luminescence efficiency of Er ions embedded in a semiconductor was investigated by growing about forty erbium-doped InGaAs/GaAs and GaAs/AlGaAs multiple quantum well samples by molecular beam epitaxy. The idea was to enhance the semiconductor-to-erbium transfer when the quantum-well and erbium-ion transition energies are equal. Photoluminescence of Er ions and Er induced defects was studied at liquid helium and higher temperatures. A strong diffusion of erbium ... |
|
| Fracture Fundamentals in Titanium Aluminides |
01 JUN 97 |
44 pages |
| Authors:
Robert O. Ritchie; A. W. Thompson; CALIFORNIA UNIV BERKELEY DEPT OF MATERIALS SCIENCE AND MINERAL ENGINEERING
|
| Fracture toughness and fatigue-crack propagation behavior at temperatures between ambient and 800 deg C has been investigated in a wide range of (gamma + alpha2) TiAl microstructures, including single-phase gamma, duplex, coarse lamellar (1-2 mm colony size), fine lamellar (^150 micron colony size), and a P/M lamellar microstructure (^65 micron colony size, ^0.1 micron lamellar spacing). The influences of colony size, lamellar spacing and volume fraction of equiaxed gamma grains ... |
|
| Ultrasonic Characterization of High Tc and other Unconventional Superconductors |
JUN 97 |
42 pages |
| Authors:
Moises Levy; WISCONSIN UNIV-MILWAUKEE DEPT OF PHYSICS
|
| Ultrasonic techniques were used to characterize the properties of high Tc and other unconventional superconductors. A pontoon technique was developed to investigate thin films with surface acoustic waves SAW. A cw sampling technique was modified in order to sensitively study vortex motion in small superconducting single crystals of YBCO. The penetration field of melt textured YBCO was observed ultrasonically and analysis of the data yields the superconducting energy gap in ... |
|
| Growth, Characterization and Device Development in Monocrystalline Diamond Films |
JUN 1997 |
44 pages |
| Authors:
R. F. Davis; R. J. Nemanich; Z. Sitar; P. Baumann; W. Liu; NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Highly oriented diamond has been grown on (100) Ni substrates by the hot filament chemical vapor deposition method. Epitaxial nuclei were obtained by diamond powder seeding and a subsequent high-temperature annealing process. Real time, in situ laser reflectometry was developed to monitor changes in surface morphology observed during the high temperature annealing since the timing of the process was crucial for the achievement of a high degree of orientation and ... |
|
| Defects and Impurities in 4H- and 6H-SiC Homoepitaxial Layers: Identification, Origin, Effect on Properties of Ohmic Contacts and Insulating Layers and Reduction |
JUN 1997 |
33 pages |
| Authors:
R. F. Davis; M. O. Aboelfotoh; B. J. Baliga; R. J. Nemanich; NORTH CAROLINA STATE UNIV AT RALEIGH
|
| Chemical vapor deposition systems are being fabricated to deposit 4H- and 6H-SiC thin films at moderate and very high temperatures. Single crystalline A1N films with smooth surfaces were grown using gas-source MBE and characterized with RHEED, XRD, TEM and SIMS. The C-V characteristics of All A1N/SiC heterostructures depended strongly on temperature from 200 to 573 K and exhibited hysteresis effects consistent with the presence of slow interface traps. The A1N/SiC ... |
|
| Selected Energy Epitaxial Deposition and Low Energy Electron Microscopy of AlN, GaN and SiC Thin Films |
JUN 97 |
28 pages |
| Authors:
R. F. Davis; H. H. Lamb; I. S. Tsong; E. Bauer; E. Chen; NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Tight-binding ab initio molecular dynamics simulations involving a generalized multicenter tight-binding formalism which includes self-consistent charge transfer between the ions were used to investigate initial stages of growth of Group III nitrides. Initial results for the lattice constants, bulk modulus, phonon frequencies and electronic structure of the zincblende and wurtzite phase of bulk GaN and AlN are in good agreement with existing experimental data and highly converged plane wave calculations. ... |
|
| Interface Properties of Wide Bandgap Semiconductor Structures |
JUN 97 |
194 pages |
| Authors:
R. F. Davis; S. Bedair; J. Bernholc; R. J. Nemanich; Z. Sitar; NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| On GaN films ICP etched at low power did not differ from unetched GaN. Leakage currents for the low power and unetched GaN were similar to -10V (less than -1nA). The forward and reverse characteristics for 100 micrometer diameter Pt contacts on GaN etched at high power were similar to those of large (150-200 micrometer diameter) unetched GaN contacts . The barrier heights for these contacts were low and the ... |
|
| AASERT: Epitaxial Metallizations of III-V Semiconductors |
JUN 97 |
18 pages |
| Authors:
P. I. Cohen; MINNESOTA UNIV MINNEAPOLIS DEPT OF ELECTRICAL ENGINEERING
|
| The nucleation and growth of three intermetallic systems on III-V semiconductors have been examined or begun. FeAl and CoGa have been grown on GaAs(100) and their structural and magnetic properties examined. For their nucleation and growth, the main techniques used were ultrahigh vacuum scanning tunneling microscopy and reflection high energy electron diffraction. Direct confirmation of the growth transition from single-layer to bilayer for FeAl was obtained. Magnetooptical Kerr effect measurements ... |
|
| Brittle to Ductile Transitions in Cleavage Fracture: Experiments and Simulations |
30 MAY 97 |
183 pages |
| Authors:
A. S. Argon; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF MECHANICAL ENGINEERING
|
| Final report summarizing the experimental studies of crack arrest in Si single crystals and associated computer simulations of key crack tip processes controlling the brittle to ductile transition from cleavage to tough behavior. |
|
| Mechanism of Doping Gallium Arsenide with Carbon Tetrachloride During Organometallic Vapor-Phase Epitaxy |
23 MAY 97 |
20 pages |
| Authors:
Michael L. Warddrip; Menno J. Kappers; Lian Li; Haihua Qi; Byung-Kwon Han; CALIFORNIA UNIV LOS ANGELES
|
| The rates of decomposition of carbon tetrachloride (CCl4), triethylgallium (TEGa) and tertiarybutylarsine (TBAs), and the rate of GaAs film growth, were measured as a function of the process conditions during organometallic vapor phase epitaxy. In addition, the reaction of CC14 with the GaAs(001) surface was monitored in ultrahigh vacuum using infrared spectroscopy, temperature programmed desorption, and scanning tunneling microscopy. These experiments have revealed that CC14 adsorbs onto Ga sites, and ... |
|
| Ligand Exchange Reactions in Organometallic Vapor-Phase Epitaxy |
23 MAY 97 |
17 pages |
| Authors:
Menno J. Kappers; Michael L. Warddrip; Kerri J. Wilkerson; Robert F. Hicks; CALIFORNIA UNIV LOS ANGELES
|
| The organometallic vapor phase epitaxy (OMVPE) of CdZnTe and InGaAs alloys has been studied using on-line infrared spectroscopy and ex-situ X-ray crystallography. During II-VI OMVPE, ligand exchange reactions between dimethylcadmium and diethylzinc produce more reactive ethylcadmium species, and less reactive methylzinc species. During III-V OMVPE, reactions between trimethylindium and triethylgallium produce more reactive ethylindium compounds and less reactive methylgallium compounds. The large difference in reactivities of these sources makes it ... |
|
| Formation and Structural Characterization of the Mixed-Metal Pnicogen- Bridged Four-Membered Ring Compounds (Et2O)2LiMU-E(SiMe3)22GaH2, E=P, As |
15 MAY 97 |
23 pages |
| Authors:
J. F. Janik; R. L. Wells; V. G. Young Jr.; Jason A. Halfen; DUKE UNIV DURHAM NC DEPT OF CHEMISTRY
|
| Two compounds with novel connectivities, (Et2O)2 LiMU-E(SiMe3)22 GaH2, E = P (1), As (2), formally lithium pnictidogallates, were synthesized in the reactions between LiGaH4 and E(SiMe3)3 in diethyl ether via trimethylsilane elimination. |
|
| Cyclopentadiene Elimination Reaction as a Route to Bis(Neopentyl)Gallium Phosphides, Crystal and Molecular Structures of (Me3CCh2)2GaPEt22 and (Me3CCH2) 2GaP(C6H11)22 |
12 MAY 97 |
30 pages |
| Authors:
O. T. Beachley Jr.; John P. Maloney; Robin D. Rogers; STATE UNIV OF NEW YORK AT BUFFALO DEPT OF CHEMISTRY
|
| A major challenge for synthetic group 13 chemistry is to discover new reactions for the preparation of ultrapure precursors for electronic materials. Thus, the simplest and most direct route which involves the most limited number of synthetic steps from the fewest reagents of high purity at the lowest possible reaction temperature should minimize the introduction of impurities. Consequently, our research has been directed toward the use of the hydrocarbon elimination ... |
|
| Substrate/Buffer Layer Compounds in the Calcium Antimonate System for Growth of Epitaxial YBCO Films |
MAY 97 |
11 pages |
| Authors:
Steven C. Tidrow; Arthur Tauber; Robert D. Finnegan; William D. Wilber; ARMY RESEARCH LAB FORT MONMOUTH NJ
|
| Using pulsed laser deposition (PLD), epitaxial thin films of Yttrium- Barium-Copper-Oxide (YBCO) have been grown on films of compounds in the calcium antimonate system, Ca2MeSbO6, where Me=Al, Ga, Sc, In, Y and La. Bulk targets of compounds were prepared from precursor oxides and carbonates using solid state reaction at temperatures between 1400 and 1500 deg C. Epitaxial relationships were determined from x-ray diffraction data. All antimonates investigated demonstrated (001) epitaxy ... |
|
| Impurity-Related Optical Emission Alloys and Superlattices |
MAY 97 |
28 pages |
| Authors:
Dennis G. Hall; ROCHESTER UNIV NY INST OF OPTICS
|
| This report describes the results of experimental investigations of impurity-related, near infrared optical emission from crystalline silicon and from silicon germanium superlattices grown by molecular beam epitaxy (MBE). Radiative impurities can be introduced into silicon germanium superlattices by post growth ion implantation or by co-evaporation during growth. The research has demonstrated, using beryllium (Be) impurities, that radiative Be-pairs can be formed during MBE growth of silicon germanium superlattices. Secondary ion ... |
|
| Fracture Analysis of Diamond Material |
30 APR 97 |
130 pages |
| Authors:
J. J. Mecholsky Jr.; Lucien P. Hehn; FLORIDA UNIV GAINESVILLE DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Polycrystalline CVD diamond disks were fractured in ball-on-ring loading. Fracture surface analysis was performed on the fractured specimens using both optical and scanning electron microscopy. Fracture surface analysis was used to locate and measure the size of the failure initiating critical flaws in over 60 specimens. |
|
| Semiconductor Ultraviolet Detectors |
25 APR 97 |
33 pages |
| Authors:
P. I. Cohen; M. I. Nathan; MINNESOTA UNIV MINNEAPOLIS DEPT OF ELECTRICAL ENGINEERING
|
| Materials and structures crucial to the development of semiconducting ultraviolet detectors were examined. The chemical beam epitaxy of GaN was compared to the growth of GaN using supersonic jet sources. The main characterization techniques employed were reflection high energy electron diffraction (RHEED) and desorption mass spectroscopy (DMS). It was found that a supersonic jet of molecular nitrogen seeded in molecular hydrogen would react at the surface to form GaN at ... |
|
| Effects of High Temperature Treatment on Curl And Microstructure of Heavily Boron Doped Silicon |
17 APR 97 |
115 pages |
| Authors:
Denise M. Bruce; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
|
| An experimental study was performed to investigate the effects of high temperature treatment on the microstructure and curling behavior of heavily boron-doped silicon structures. Cantilever structures were created from p++ boron diffused silicon wafers. The post-diffusion high temperature 'anneal' treatment temperature was varied while the anneal time remained constant. The micromechanical cantilevers were analyzed for curl as a function of the anneal temperature using an optical profiler. Bulk sections from ... |
|
| Interaction of Regional and Teleseismic Waves with 3-D Earth Structure |
16 APR 97 |
83 pages |
| Authors:
Brian L. Kennett; AUSTRALIAN NATIONAL UNIV CANBERRA RESEARCH SCHOOL OF EARTH SCIENCES
|
| This report describes a range of studies which have been directed at improved delineation of structure at regional scales which can be used in calibrating seismic information from regional or teleseismic sources. The first two sections describe the development of fine-scale three- dimensional models for the crust and lithosphere incorporating a broad class of seismic information and the extension of such procedures to include anisotropy. The next part develops a ... |
|
| Materials for Adaptive Structural Acoustic Control. Volume I |
14 APR 97 |
218 pages |
| Authors:
L. E. Cross; PENNSYLVANIA STATE UNIV UNIVERSITY PARK MATERIALS RESEARCH LAB
|
| This report documents work carried out largely over the fifth and final year of the ONR sponsored University Research Initiative (URI) entitled 'Materials for Adaptive Structural Acoustic Control.' This program has continued to foster the successful development of new electroceramic single crystal and composite material combinations for both sensing and actuation functions in adaptive structural systems. |
|
| Materials for Adaptive Structural Acoustic Control. Volume II |
14 APR 97 |
181 pages |
| Authors:
L. E. Cross; PENNSYLVANIA STATE UNIV UNIVERSITY PARK MATERIALS RESEARCH LAB
|
| This report documents work carried out largely over the fifth and final year of the ONR sponsored University Research Initiative (URI) entitled 'Materials for Adaptive Structural Acoustic Control.' This program has continued to foster the successful development of new electroceramic single crystal and composite material combinations for both sensing and actuation functions in adaptive structural systems. |
|
| Materials for Adaptive Structural Acoustic Control. Volume III |
14 APR 97 |
158 pages |
| Authors:
L. E. Cross; PENNSYLVANIA STATE UNIV UNIVERSITY PARK MATERIALS RESEARCH LAB
|
| This report documents work carried out largely over the fifth and final year of the ONR sponsored University Research Initiative (URI) entitled 'Materials for Adaptive Structural Acoustic Control.' This program has continued to foster the successful development of new electroceramic single crystal and composite material combinations for both sensing and actuation functions in adaptive structural systems. |
|
| Materials for Adaptive Structural Acoustic Control. Volume IV |
14 APR 97 |
178 pages |
| Authors:
L. E. Cross; PENNSYLVANIA STATE UNIV UNIVERSITY PARK MATERIALS RESEARCH LAB
|
| This report documents work carried out largely over the fifth and final year of the ONR sponsored University Research Initiative (URI) entitled 'Materials for Adaptive Structural Acoustic Control.' This program has continued to foster the successful development of new electroceramic single crystal and composite material combinations for both sensing and actuation functions in adaptive structural systems. |
|
| Materials for Adaptive Structural Acoustic Control. Volume V |
14 APR 97 |
162 pages |
| Authors:
L. E. Cross; PENNSYLVANIA STATE UNIV UNIVERSITY PARK MATERIALS RESEARCH LAB
|
| This report documents work carried out largely over the fifth and final year of the ONR sponsored University Research Initiative (URI) entitled 'Materials for Adaptive Structural Acoustic Control.' This program has continued to foster the successful development of new electroceramic single crystal and composite material combinations for both sensing and actuation functions in adaptive structural systems. |
|
| Materials for Adaptive Structural Acoustic Control. Volume VI |
14 APR 97 |
161 pages |
| Authors:
L. E. Cross; PENNSYLVANIA STATE UNIV UNIVERSITY PARK MATERIALS RESEARCH LAB
|
| This report documents work carried out largely over the fifth and final year of the ONR sponsored University Research Initiative (URI) entitled 'Materials for Adaptive Structural Acoustic Control.' This program has continued to foster the successful development of new electroceramic single crystal and composite material combinations for both sensing and actuation functions in adaptive structural systems. |
|
| The Formation of Nanocrystalline Semiconductor Particles within a Bicontinuous Cubic Phase |
08 APR 1997 |
32 pages |
| Authors:
Jianping Yang; Banahalli Ratna; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| Nanocrystalline semiconductors are synthesized within a bicontinuous cubic matrix. The nanocrystalline particles may then be end-capped with a dispersant to prevent agglomeration. One typical nanocrystalline semiconductor compound made according to the present invention is PbS. Other IV-VI semiconductors may be produced by the method of the present invention. The method of this invention may also be used to produce doped semiconductors. |
|
| Nanocrystalline Processing and Interface Engineering of Si3N4-Based Nanocomposites |
01 APR 97 |
7 pages |
| Authors:
Jackie Y. Ying; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF CHEMICAL ENGINEERING
|
| With careful powder handling procedures and processing, the nanocrystalline TiN produced in our novel reactor undergoes tremendous sintering and densification to produce dense (99%) TiN materials at 1400 deg C. in a simple, pressureless sintering process. This report outlines our continued work on the synthesis, sintering and processing of nanocrystalline TiN. Improvements to the filter collection unit in our reactor continue to be made. A SEM/BET study of the microstructure ... |
|
| Expitaxial Growth of SiC Using MBE. Phase I |
APR 97 |
28 pages |
| Authors:
Amarendra K. Rai; UNIVERSAL ENERGY SYSTEMS INC DAYTON OH
|
| This report addresses the development of molecular beam epitaxy technique for the growth of SiC thin film. In the course of this work, a molecular beam epitaxy system, Riber 32 GSMBE, was installed at the University of Cincinnati. The details of the MBE system are described in this report. Two preliminary experiments were carried out to demonstrate the epitaxial growth of SiC thin film. In the first experiment a Si-on-Insulator ... |
|
| (AASERT-92) Arsenic Cluster Engineering for High Speed Photoconductors |
APR 1997 |
12 pages |
| Authors:
Michael R. Malloch; PURDUE UNIV LAFAYETTE IN DEPT OF ELECTRICAL ENGINEERING
|
| GaAs epilayers grown at low substrate temperatures by molecular beam epitaxy contain arsenic antisites and gallium vacancies. With anneal these point defects form arsenic precipitates. We have investigated GaAs epilayers with a wide range of excess arsenic concentrations and anneal conditions to study the role of the point defects and arsenic precipitates in carrier trapping and recombination: we have determined the electron and hole capture cross sections for the arsenic ... |
|
Crystallography
