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Advances in LIGA-Based Post-Mold Fabrication
No full textThe establishment of a process to allow planarization of deep x-ray lithography based microfabncated metal components via diamond lapping has enabled examination of three additional microfabrication issues. The areas of improvement that are discussed include materials, microassembly and packaging, and multilevel fabrication. New materials work has centered on magnetic materials including precision micromagnets and surface treatments of electrodeposited materials. Assembly and packaging has been aided by deep silicon etch processing and the use of conventional precision milling equipment combined with press-tit assembly. Diffhsion bonding is shown to be a particularly important approach to achieving multilevel metal mechanisms and furthermore shows promise for achieving batch assembled and packaged high aspect-ratio metal micromechanics
Unipolar Complementary Circuits Using Double Electron Layer Tunneling Tansistors
No full textWe demonstrate unipolar complementary circuits consisting of a pair of resonant tunneling transistors based on the gate control of 2D-2D interlayer tunneling, where a single transistor - in addition to exhibiting a welldefined negative-differential-resistance can be operated with either positive or negative transconductance. Details of the device operation are analyzed in terms of the quantum capacitance effect and band-bending in a double quantum well structure, and show good agreement with experiment. Application of resonant tunneling complementary logic is discussed by demonstrating complementary static random access memory using two devices connected in series
Damage to III-V Devices During Electron Cyclotron Resonance Chemical Vapor Deposition
No full textGaAs-based metal semiconductor field effect transistors (MESFETS), heterojunction bipolar transistors (HBTs) and high electron mobility transistors (HEMTs) have been exposed to ECR SiJ&/NH3 discharges for deposition of SiNX passivating layers. The effect of source power, rf chuck power, pressure and plasma composition have been investigated. Effects due to both ion damage and hydrogenation of dopants are observed. For both HEMTs and MESFETS there are no conditions where substantial increases in channel sheet resistivity are not observed, due primarily to (Si-H)O complex formation. In HBTs the carbon-doped base layer is the most susceptible layer to hydrogenation. Ion damage in all three devices is minimized at low rf chuck power, moderate ECR source power and high deposition rates
Seismic Response of a Deep Underground Geologic Repository for Nuclear Waste at the Waste Isolation Pilot Plant in New Mexico
No full textThe Waste Isolation Pilot Plant (WIPP) is a deep underground nuclear waste repository certified by the U.S. Environmental Protection Agency ,(EPA) to store transuranic defense-related waste contaminated by small amounts of radioactive materials. Located at a depth of about 655 meters below the surface, the facility is sited in southeastern New Mexico, about 40 Department of Energy underground facilities, waste disposal. kilometers east of the city of Carlsbad, New Mexico. The U.S. (DOE) managed the design and construction of the surface and and remains responsible for operation and closure following The managing and operating contractor for the DOE at the WIPP, Westinghouse Electric Corporation, maintains two rechmiant seismic monitoring systems located at the surface and in the underground. This report discusses two earthquakes detected by the seismic monitoring system, one a duratior magnitude 5.0 (Md) event located approximately 60 km east-southeast of the facility, and another a body-wave magnitude 5.6 (rob) event that occurred approximately 260 kilometers to the south-southeast
Spatially Resolved Atomic and Molecular Spectroscopy in Microelectronics Processing Plasmas
No full textPlasma processing of microelectronic materials is strongly dependent on the generation and control of neutral radial and ion species generated in a plasma. For example, process uniformity across a #er is drken by a combination of plasma charged particle and neutral uniformity. Due to extensive rexarch and engineering the current generation of commercial plasma reactors can generate very radially uniform ion distributions, usually better than ~ 2 perwnt as determined by ion saturation measurements. Due in part to the difficulty associated with determining the neutral radial distributions, control of the neutral radical uniformity is less well developed. This abstract will review our recent measurements of the spatial distribution of severaI important atomic and molecukw species in inductively coupled plasmas through C12 / BCIJ / Ar containing gas mixtures. Measured species include the ground state Cl and BC1 densities as well as the metastable argon density. The fbeus of this review will be on the experimental techniques and results. In addition to assisting in the development of a fbndarnental understanding of the important pkunna physics, these measurements have been used to benchmark multi dimensional plasma discharge codes
On Practical Modifications to the Barnes-Hut Multipole Method for Electromagnetic Scattering
No full textThis paper presents a simple methodology for quickly predicting and optimizing computer run time for the Barnes-Hut multipole method for boundary element electromagnetic scattering problems. The methodology is easily extended to other multipole methods (e.g., Greengard-Rokhlin) and to other physics. The idea is to simply COZM t the number of element-cell interactions, number of direct element- element interactions, and the number of cell multipole expansion creations (each expansion weighted by the number of elements in the cell), and then finally combine these three results with the associated unit costs to obtain the total computer :un-time to perform a single matrix-vector multiply. By counting operations instead of actually performing them, the time to predict the computer run time is orders of magnitude smaller than the time to actually perform the associated calculations. This allows for very quick optimization of parameters, such as the maximum number of elements in a final generation cell of the tree. Numerical examples are presented herein in which the rate of return (time saved over time spent finding optimal parameter values) is significantly more than two orders of magnitude
Esperanzaite, NaCa(2)Al(2)(As(5+)O(4))[As(5+)O(3)(OH)](OH)(2)F(4)(H(2)O), A New Mineral From Mina La Esperanza, Mexico: Descriptive Mineralogy and Atomic Arrangement
No full textEsperanzaite, ideally NaCazA12(As5+0.i)[As5+03 (OH)] (OH)2FJH20), Z =2, is a new mineral from the Mina h Esperarq Durango State, Mexico. The mineral occurs as blue-green botryoidal crystalline masses on rhyolite, with separate spheres up to 1.5 mm Y Deceased in diameter. Mobs hardness is 4.5, specific gravity 3.240h, and 3.36( 3)C.IC. Optical properties were measured in 589 nm light. Esperanzaite is biaxial (-), .Y= Y = Z= colorless, a 1.580(1), ~ 1.588( 1), and y 1.593(1 ); 2V0hs is 74(1 ~ and 2 }'CUIC is 76.3". Dispersion is medium, r 80, 001, 020; 4.796,80,011. Esperanzaite is monoclinic, u 9.687(5), b 10.7379(6), c 5.5523(7)& ~ 105.32( 1 )", space group P21/nz. The atomic arrangement of esperanzaite was solved by Direct Methods and Fourier analysis (R= 0.03 1). The Fundamental Building Block is formed of stacks of heteropolyhedral tetramers; the tetramers are formed of two arsenate tetrahedral and two Al octahedra, comer-linked in 4-member rings. The Fundamental Building Blocks are linked by irregular lda~j and Ca@ polyhedra
Short Contact Time Direct Coal Liquefaction Using a Novel Batch Reactor
No full textThe primary objective of this research is to optimize the design and operation of the bench scale batch reactor (SCTBR) for studying direct coal liquefaction at short contact times (.01 to 10 minutes or longer) . An additional objective is to study the kinetics of direct coal liquefaction particularly at short reaction times. Both of these objectives have been nearly achieved, however this work has shown the great importance of the liquefaction solvent characteristics and the solvent-catalyst interaction on the liquefaction process. This has prompted us to do a preliminary investigation of solvents and the solvent-catalyst systems in coal liquefaction. SUMMARY AND CONCLUSIONS 1) Conversion vs time data have been extended to 5 coals of ranks from lignite to low volatile bituminous coal. A broad range of reaction rates have been observed with a maximum in the high volatile bituminous range. 2) A series of direct coal liquefaction runs have been made using a range of nitrogen containing solvents that given high liquefaction conversions of coal. These runs are now being analyzed. 3) The coalification process has been shown by TGA to go through an intermediate stage which may account for the greater reactivity of bituminous coals in the direct coal liquefaction process. 4) It was shown that coal rank can be accurately determined by thermogravimetric analysi
Analytical services Organization Union Valley sample Preparation facility Polychlorinated Biphenyl (PCB) Annual Inventory Document
No full textThe Analytical Services Organization (ASO), Union Valley Sample Preparation Facility (UVSPF), provides analytical testing in support of the Department of Energy (DOE), Oak Ridge Operations (ORO), and associated sites. Samples generated on the Oak Ridge Reservation (ORR) are routinely received at the WSPF for analytical evaluatiotiidentification. Many of these samples are polychlorinated biphenyl (PCB) regulated from a source or being sent to the facility to determine PCB content. PCB laboratory wastes in solid and liquid form are generated during the evaluation of these materials, requiring the WSPF staff to maintain formal storage areas for staging the materials prior to off-site shipment for disposal. The purpose of this report is to fulfill the requirements set forth in Title 40, Code of Federal Regulations (CFR), Part 761.180(a), Subpart J, which requires owners or operators of a facility using or storing PCBS to prepare an annual inventory document by July 1 of the current year which covers the previous calendar year. This report provides documentation of the inventory of PCB materials/wastes that were generated, stored for dispos~ and shipped off site for disposal for the period January 1, 1997, to January 1, 1998. The following is a summary of materials/wastes subject to the aforementioned reporting requirements
Evaluation of Calendar Year 1997 Groundwater and Surface Water Quality Data For The Upper East Fork Poplar Creek Hydrogeologic Regime At The U.S. Department of Energy Y-12 Plant, Oak Ridge, Tennessee
No full text1 1.0 INTRODUCTION This report presents an evaluation of the groundwater quality monitoring data reported in: Calendar Year 1997 Annual Groundwatw Monitoring Report for the Upper East Fork Poplar Creek Hydrogeologtc Rep-meat the US. Department of Energy Y-12 Plant, Oak Ridge, Tennessee (AJA Technical Services, Inc. 1998), which is hereafter referenced as the Annual Monitoring Report. Section 2.0 presents background information for the Upper East Fork Poplar Creek Hydrogeologic Regime (East Fork Regime) that is relevant to data evaluation, including brief descriptions of the geology, the groundwater flow system, the contaminant source areas, and the extent of groundwater contamination in the regime. Section 3.0 provides an overview of the groundwater sampling and analysis activities petiormed during calendar year (CY) 1997, including monitoring well locations, sampling frequency and methods, and laboratory analyses. Evaluation and interpretation of the monitoring da% described in Section 4.0, is generally focused on an overview of data quality assurance/quality control (QA/QC), long-term concentration trends for selected inorganic, organic, and radiological contaminants, and consistency with applicable site-specific conceptual contaminant transport models described in: Report on the Remedial Investigation of the Upper East Fork Poplar Creek Characterization Area at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee (U.S. Department of Energy 1998), which is referenced hereafter as the Remedial Investigation @I) Report. Findings of the data evaluations are summarized :in Section 5.0 and a list of technical reports and regulatory documents cited for more detailed irdormation (Section 6.0) concludes the report. All of the illustrations (maps and trend graphs) and data summary tables referenced in the text are presented in Appendm A and Appendix B, respectively. Appendix C provides a summary of the analytical results that meet applicable data quality objectives (DQOS) of the Y-12 Plant Groundwater Protection Program