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Some Compounds of Plutonium With Metalloid Elements

Description: From abstract: "Experimental methods of the type employed for alloy preparation in metallurgical research have been used in attempts to prepare compounds of plutonium with four different metalloid elements: phosphorous, arsenic, selenium, and tellurium. By means of their X-ray diffraction patterns the existences of six previously unknown compounds have been established, but the composition and crystal structures of only three of the compounds have been determined."
Date: 1955
Creator: Gorum, Alvin Eugene
Partner: UNT Libraries Government Documents Department

Stress relaxation of cellular silicone material: 1980

Description: Bendix Kansas City currently is evaluating the long-term (10 years) stress relaxation properties of cellular silicone materials at room temperature. The cellular structure is formed by using urea as a leachable filler. Both equilibrium (random copolymer) and condensation (block copolymer) type base polymers are included. Each material was compounded to yield two different densities for several thickness combinations. These density-thickness combinations then were compressed to nominal compressions of 20 and 40 percent with nine replicates at each condition. Five are tested regularly, two are 3 year controls, and two are 10 year controls.
Date: September 1, 1980
Creator: Schneider, J.W.
Partner: UNT Libraries Government Documents Department

Heat exchanger: ingot casting/slicing process. Silicon sheet growth development for the large area silicon sheet task of the low cost silicon solar array project. First quarterly report, November 20, 1975--December 31, 1975

Description: Designs for changes to the existing crystal casting furnace and multi-wafer slicer were completed prior to the contract. Equipment supplies necessary for the modifications and silicon material were ordered during the first one and one-quarter month period covered. Assembly preparation and check-out of all systems are on schedule. (auth)
Date: December 31, 1975
Creator: Schmid, F.
Partner: UNT Libraries Government Documents Department

Silicon ribbon growth by a capillary action shaping technique. Quarterly technical progress report No. 6

Description: The effects of capillary die design on dopant distribution are described. A new technique for thermal geometry control utilizing inert-gas purging was implemented. Routine 38-mm-wide ribbon growth was demonstrated. 50-mm-wide ribbon growth in a length over one meter was achieved. A technology projection and guide to future silicon sheet growth was completed. (WDM)
Date: December 15, 1976
Creator: Schwuttke, G. H.; Ciszek, T. F. & Kran, A.
Partner: UNT Libraries Government Documents Department

Effect of Electronic Excitation on Thin Film Growth

Description: The effect of nanosecond pulsed laser excitation on surface diffusion during growth of Ge on Si(100) at 250 degrees C was studied. In Situ reflection high-energy electron diffraction (RHEED) was used to measure the surface diffusion coefficient while ex situ atomic force microscopy (AFM) was used to probe the structure and morphology of the grown quantum dots. The results show that laser excitation of the substrate increases the surface diffusion during growth of Ge on Si(100), changes the growth morphology, improves crystalline structure of the grown quantum dots, and decreases their size distribution. A purely electronic mechanism of enhanced surface diffusion of the deposited Ge is proposed. Ge quantum dots were grown on Si(100)-(2x1) by pulsed laser deposition at various substrate temperatures using a femtosecond Ti:sapphire laser. In-situ reflection high-energy electron diffraction and ex-situ atomic force microscopy were used to analyze the fim structure and morphology. The morphology of germanium islands on silicon was studied at differect coverages. The results show that femtosecond pulsed laser depositon reduces the minimum temperature for epitaxial growth of Ge quantum dots to ~280 degrees C, which is 120 degrees C lower then previously observed in nanosecond pulsed laser deposition and more than 200 degrees C lower than that reported for molecular beam epitaxy and chemical vapor deposition.
Date: January 31, 2011
Creator: Elsayed-Ali, Hani E.
Partner: UNT Libraries Government Documents Department

Selective Au-Si eutectic bonding for Si-based MEMS applications

Description: A novel method of fabricating three-dimensional silicon micro electromechanical systems (MEMS) is presented, using selectivity thin film deposited Au-Si eutectic bond pads. Utilizing this process, complicated structures such as microgrippers and microchannels are fabricated. Bond strengths are higher than the silicon fracture strength and the bond areas can be localized and aligned to the processed wafer. The process and the applications are described in this paper.
Date: May 22, 1995
Creator: Lee, A.; Lehew, S. & Yu, C.
Partner: UNT Libraries Government Documents Department

Effects of electronically neutral impurities on muonium in germanium

Description: Low-temperature measurements of muonium parameters in various germanium crystals have been performed. We have measured crystals with different levels of neutral impurities, with and without dislocations, and with different annealing histories. The most striking result is the apparent trapping of Mu by silicon impurities in germanium.
Date: April 1, 1983
Creator: Clawson, C.W.; Crowe, K.M.; Haller, E.E.; Rosenblum, S.S. & Brewer, J.H.
Partner: UNT Libraries Government Documents Department

TEM studies of P/sup +/ implanted and subsequently laser annealed Si

Description: The present investigation is concerned with laser annealing of P/sup +/ implanted Si. The aim of the work was to study the crystallization behavior of damage structure occurring due to high dose rate implantation using transmission electron microscopy (TEM) as the method of examination.
Date: May 1, 1979
Creator: Sadana, D.K.; Wilson, M.C.; Booker, G.R. & Washburn, J.
Partner: UNT Libraries Government Documents Department

Web-dendritic ribbon growth. USC solar report No. Q-3

Description: The web growth investigation portion of this program was spent in growing a backlog of primitive dendrites and developing a number of dendritic seed crystals having a variety of twin plane spacings. These seeds are to be used in the determination of the optimum twin spacing for dendritic-web growth. Having determined the optimum twin spacing for the seed dendrites, the optimized seeds will be used in the experimental part of the investigation to determine the limitation on the growth width and pull rate of the dendritic-web section. Primitive dendrities containing 2,3,4, and 5 twin planes with twin plane spacings of 0.6 to 19.2 mm. have been grown. A supply of dendrite seed crystals have been grown from these primitive dendrites. Computer programs have been developed that appear adequate for the thermal analysis of the dendritic-web growth. A preliminary two dimensional thermal model of the melt, crucible, susceptor and lid has been completed and numerical results obtained. In this model only radiation heat transfer was assumed for the lid. The temperature profiles obtained were thus lower than is found experimentally in the furnace. The characterization experiments have all been tested and found adequate for characterization of the material grown in the dendritic-web furnace.
Date: June 22, 1976
Creator: Hilborn, R. B. Jr. & Faust, J. W. Jr.
Partner: UNT Libraries Government Documents Department

Floating substrate process. Large area silicon sheet task low-cost silicon solar array project. Third quarterly progress report, June 21, 1976--September 24, 1976

Description: The Seeded Growth Furnace was completed and operated extensively during the third quarter. Optimum thermal geometry, gas flows, and withdrawal rates are being determined. Surface growth was obtained having growth velocity as high as 5 to 6 mm/min. The surface growth has generally taken the form of interlocking crystals and is thin enough to follow the liquid surface. Its thickness has been determined in one case to be 20 microns. A molybdenum susceptor has been made for the seeded growth furnace. It is anticipated that this new design will eliminate the problems caused by films on the melt and seed crystal and lead to improved crystal structure in the silicon growth. A series of experiments were performed in order to determine whether the reactor gas streams were sources of contamination. Nitrogen reacts with silicon at 1100/sup 0/C to coat its surface with a film 30 to 150A thick. Silicon heated in hydrogen at temperatures between 1000 and 1200/sup 0/C maintains a very clean, film-free surface.
Date: September 27, 1976
Creator: Garfinkel, M. & Hall, R. N.
Partner: UNT Libraries Government Documents Department

Web-dendritic ribbon growth. Annual report, October 1, 1975--September 31, 1976

Description: The web furnace has been set up, calibrated, and made operational for pulling dendritic-web samples. Considerable work has been completed in the investigation of the effect of changes in the furnace thermal geometry, as accomplished by variations in the number, size, shape, and location of thermal shields, on the growth of dendritic-web. Numerous growth runs were made to grow primitive dendrites for use as the dendritic seed crystals for the web growth. Some preliminary investigations were conducted to try and determine the optimum twin spacing in the dendritic seed crystal for web growth. Models were developed and computer programs applied to ascertain the thermal geometries present in the susceptor, crucible melt, meniscus, and web. A major result of this analysis has been the prediction of an upper limit on the pull rate of approximately 4 cms. per minute with the thermal geometry presented in our furnace. The facilities for obtaining characterization data were set-up and made operational. Data on twin spacings and number of twin planes in the dendritic seed crystals and resulting web samples was obtained. Resistivity and majority charge carrier type determinations were made on a few select web samples. All samples to date have been high resistivity, undoped, p-type. (WDM)
Date: October 1, 1976
Creator: Hilborn, Jr., R. B. & Faust, Jr., J. W.
Partner: UNT Libraries Government Documents Department

Heat Exchanger-Ingot Casting/Slicing Process. Silicon sheet growth development for the large area silicon sheet task of the Low Cost Silicon Solar Array Project. Fourth quarterly progress report, June 19, 1976--September 24, 1976

Description: Good seeding and growth were achieved during the past quarter with the Heat Exchanger Method at melt superheats below 10/sup 0/C. To achieve a high enough seeding temperature at low superheat, the heat exchanger was raised one inch higher in the heat zone. For this higher position, seeding conditions had to be re-established since the temperature profile across the diameter of the heat zone was flatter; i.e., the temperature in the middle of the heat zone was closer to the temperature near the heating element. All the boules produced to date have cracked during cool down, regardless of the annealing and cool-down cycle. The cracking appears to be due to the expansion mismatch between the silicon and the silica which are tenaciously bonded together. The tabulation of the heat-exchanger and furnace temperatures for this quarter's runs are presented. (WDM)
Date: September 24, 1976
Creator: Schmid, F. & Reynolds, B.
Partner: UNT Libraries Government Documents Department

Low cost silicon solar array project. Task I. Establishment of the feasibility of a process capable of low cost, high volume production of silane, SiH/sub 4/. Annual report

Description: The web furnace was set up, calibrated, and made operational for pulling dendritic-web samples. Numerous growth runs were made to grow primitive dendrites for use as the dendritic seed crystals for the web growth. Models were developed and computer programs applied to ascertain the thermal geometries present in the susceptor, crucible melt, meniscus and web. The facilities for obtaining characterization data have been set up and made operational. (WDM)
Date: October 1, 1976
Creator: Breneman, W. C. & Mui, J. Y. P.
Partner: UNT Libraries Government Documents Department

Large area silicon sheet by EFG. Annual progress report, October 29, 1975--September 30, 1976

Description: At the end of one year the program is on schedule. EFG ribbon growth system JPL No. 2 is being used to perform meaningful growth rate and ribbon thickness experiments. The new, wide ribbon growth system is in operation. A theoretical study of stresses in ribbons is reported. EFG ribbons have been observed to exhibit a characteristic defect structure which is orientation dependent in the early stages of growth.
Date: September 15, 1976
Creator: Morrison, A. D.; Ravi, K. V.; Hari Rao, C. V.; Surek, T.; Bliss, D. F.; Garone, L. C. et al.
Partner: UNT Libraries Government Documents Department

Model of amorphous-silicon-layer regrowth

Description: A new model which combines the heterogeneous nucleation and growth process for the mechanism of regrowth of amorphous silicon, in contact with a single crystal substrate, is presented. The model explains the effects of substrate orientation and impurity concentration on the kinetics of regrowth and also on the formation of twins during regrowth. The mechanism of redistribution of impurities and the formation of secondary defects during crystal regrowth are also discussed. A comparison of experimental results with the predictions of the model is also included.
Date: January 1, 1983
Creator: Ling, P.
Partner: UNT Libraries Government Documents Department

Study of local atomic and electronic structure in glassy metallic alloys. Progress report, December 1, 1979-November 1, 1980

Description: During the first reporting period, March 1, 1979-December 1, 1979, small clusters such as Fe/sub 4/, Ni/sub 4/, Ni/sub 2/Fe/sub 2/ alone and containing the metalloid atoms P and B were investigated. The effect of P and B on the magnetic moment of the clusters was investigated and found to parallel the known experimental trend. Significant metal-metalloid bonding was found in all the clusters studied. During the present reporting period a detailed analysis of the bonding in these small clusters was carried out. As a result of this detailed analysis a very significant conclusion has been reached: there are preferential metal-metalloid interactions which are predicted on the basis of the calculations. Room temperature extended x-ray absorption fine structure (EXAFS) spectra above the K absorption edge of metal constituents in the following metal-metalloid and metal-metal glasses have been measured in the February and June 1980 runs at Stanford Synchrotron Radiation Laboratory: Fe/sub 1-x/B/sub x/, (FeNi)/sub 1-x/B/sub x/, Ni/sub 1-x/B/sub x/; Zr/sub 1-x/M/sub x/ (M- Fe, Co, Ni and Cu) and Nb/sub 1-x/Ni/sub x/.
Date: January 1, 1980
Creator: Messmer, R.P. & Wong, J.
Partner: UNT Libraries Government Documents Department

Bulk band gaps in divalent hexaborides: A soft x-ray emission study

Description: Boron K-edge soft x-ray emission and absorption are used to address the fundamental question of whether divalent hexaborides are intrinsic semimetals or defect-doped bandgap insulators. These bulk sensitive measurements, complementary and consistent with surface-sensitive angle-resolved photoemission experiments, confirm the existence of a bulk band gap and the location of the chemical potential at the bottom of the conduction band.
Date: October 3, 2001
Creator: Denlinger, Jonathan D.; Gweon, Gey-Hong; Allen, James W.; Bianchi, Andrea D. & Fisk, Zachary
Partner: UNT Libraries Government Documents Department

Functional Analysis and Discovery of Microbial Genes Transforming Metallic and Organic Pollutants: Database and Experimental Tools

Description: Microbial functional genomics is faced with a burgeoning list of genes which are denoted as unknown or hypothetical for lack of any knowledge about their function. The majority of microbial genes encode enzymes. Enzymes are the catalysts of metabolism; catabolism, anabolism, stress responses, and many other cell functions. A major problem facing microbial functional genomics is proposed here to derive from the breadth of microbial metabolism, much of which remains undiscovered. The breadth of microbial metabolism has been surveyed by the PIs and represented according to reaction types on the University of Minnesota Biocatalysis/Biodegradation Database (UM-BBD): http://umbbd.ahc.umn.edu/search/FuncGrps.html The database depicts metabolism of 49 chemical functional groups, representing most of current knowledge. Twice that number of chemical groups are proposed here to be metabolized by microbes. Thus, at least 50% of the unique biochemical reactions catalyzed by microbes remain undiscovered. This further suggests that many unknown and hypothetical genes encode functions yet undiscovered. This gap will be partly filled by the current proposal. The UM-BBD will be greatly expanded as a resource for microbial functional genomics. Computational methods will be developed to predict microbial metabolism which is not yet discovered. Moreover, a concentrated effort to discover new microbial metabolism will be conducted. The research will focus on metabolism of direct interest to DOE, dealing with the transformation of metals, metalloids, organometallics and toxic organics. This is precisely the type of metabolism which has been characterized most poorly to date. Moreover, these studies will directly impact functional genomic analysis of DOE-relevant genomes.
Date: December 9, 2004
Creator: Wackett, Lawrence P. & Ellis, Lynda B.M.
Partner: UNT Libraries Government Documents Department

Development of methods of producing large areas of silicon sheet by the slicing of silicon ingots using inside-diameter (I. D. ) saws. Final report, May 1979-April 1980

Description: I.D. wafering equipment, blades and processes were used to develop methods for producing large areas of silicon sheet. Modifications to a 16 inch STC automated saw included programmable feed system; crystal rotating system; and STC dyna-track blade monitoring and control system. By controlling the plating operation and by grinding of the cutting edge, we were able to produce 16 inch I.D. blades with a cutting edge thickness of .22 mm. Crystal rotation mechanism was used to slice 100 mm diameter crystals with a 16 inch blade down to a thickness of .20 mm. Cutting rates with crystal rotation were generally slower than with standard plunge I.D. slicing techniques. Using programmed feeds and programmed rotation, maximum cutting rates were from 0.3 to 1.0 inches per minute.
Date: January 1, 1980
Creator: Aharonyan, P.
Partner: UNT Libraries Government Documents Department

Effect of laser annealing on the redistribution of boron in ion implanted and boron deposited silicon

Description: Secondary ion mass analysis (SIMS) is used to investigate the effect of laser annealing on the distribution of boron in the surface region of (100) silicon. Pulsed laser annealing was carried out using the Q-switched output of a ruby laser (20 x 10/sup -9/ sec pulse duration time). Above a pulse threshold energy of approx. 1/J cm/sup -2/, substantial alteration of the as-implanted profile of B occurred. The as-implanted profile was very nearly Gaussian, but after annealing the profile was almost uniform from the surface down to a depth of approximately twice the projected range. Redistribution of B was found to be both pulse energy and pulse number dependent. The effect of laser annealing on a thin evaporation deposited layer of B on (100) silicon was also studied. In this case a monotomically decreasing profile which resembled a Gaussian peaked at the surface resulted. A possible explanation for the redistribution of B in the surface region of (100) silicon involves melting of the near surface region during laser irradiation.
Date: January 1, 1978
Creator: Christie, W.H. & White, C.W.
Partner: UNT Libraries Government Documents Department

Effect of microstructure on the arsenic profile in implanted silicon

Description: According to an irradiation damage model, the profile of an implanted ion at temperature great enough for diffusion to occur will depend on the sink density in the material. To test this model, pure silicon wafers were prepared with high and low dislocation densities. These wafers were implanted with about 5 x 10/sup 19/ As/sup +2//m/sup 2/ at 77/sup 0/K, 300/sup 0/C, and 600/sup 0/C. After implanting the profiles were measured using Rutherford backscattering spectroscopy and secondary ion mass spectroscopy. The observed spreading of the As-profile contradicts initial theoretical predictions. Further speculation is presented to explain the differences.
Date: October 1, 1985
Creator: Coghlan, W.A.; Rhee, M.H.; Williams, J.M.; Streit, L.A. & Williams, P.
Partner: UNT Libraries Government Documents Department

Slicing of silicon into sheet material. Silicon sheet growth development for the large area silicon sheet task of the Low Cost Silicon Solar Array Project. Tenth quarterly report, June 19--October 27, 1978

Description: The limits of blade tolerances are defined. The standard blades are T-2 thickness tolerance: T-O blades are unacceptable. Further testing is necessary to demonstrate feasibility or infeasibility of T-1 blades. Good results have been obtained by using a slurry fluid consisting of mineral oil and a lubricity additive. Cost would be about $0.25 per gallon per run, 1/4 of the cost goal. Adjustments of the formulation and fine tuning of the cutting process with the new fluid are necessary. Test results and consultation indicate that the blade breakage encountered with water based slurries is unavoidable. Two full capacity (974 wafer) runs have been made on the large prototype saw. Both runs resulted in extremely low yield, however, the reasons for the low yields were lack of proper technique rather than problems with machine function. Finally, the tests on the effect of amount of material etched off of an as-sawn wafer on solar cell efficiency have been completed. The results agree with previous work at JPL in that the minimum material removed per side that gives maximum efficiency is on the order of 10 ..mu..m.
Date: November 20, 1978
Creator: Fleming, J R
Partner: UNT Libraries Government Documents Department

Development of advanced Czochralski growth process to produce low-cost 150-kg silicon ingots from a single crucible for technology readiness. First quarterly progress report, October 1, 1980-December 31, 1980

Description: Design, release for manufacture, and procurement of a modified CG2000 RC crystal grower proceeded. The construction, installation, and test of this machine is expected by March 1, 1981. The process development work will begin when the grower is completed. All of the hot zones, polycrystalline silicon, crucibles, dopant, seeds, and other supplies were quoted and purchase orders issued. Several exhaust gas analysis system equipment specifications and quotations were received and are under study. Process control requirements have been defined and design work on the melt temperature, melt level and continuous diameter control begun. Sensor development included assembly and testing of a bench prototype of a diameter scanner system.
Date: January 1, 1980
Partner: UNT Libraries Government Documents Department