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Scalable High Performance Computing Conference

作者： S.H. Bokhari H. Berryman Department of Electrical Engineering University of Engineering and Technology Lahore Pakistan Institute for Computer Applications in Science & Engineering NASA-Langley Research Center Hampton VA USA

The complete exchange ('all-to-all personalized') communication pattern is at the heart of numerous important multicomputer algorithms. Recent research has shown how this pattern can efficiently be performed on circuit-switched hypercubes. However, on circuit-switched meshes, this pattern is difficult to perform efficiently because the sparsity of the mesh interconnect leads to severe link contention. The authors develop a family of algorithms that proceed by recursively carrying out a series of contention-free exchanges on subdivisions of the mesh. Each member of this family is useful for some range of the parameters: mesh size, message size, startup time, and data transmission and permutation rates. The authors describe the performance of their algorithms on the Touchstone Delta mesh.< >

关键词： Switching circuits Hypercubes Communication switching Programming profession Power engineering computing NASA Distributed computing Power engineering and energy Hardware Integrated circuit interconnections

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PERFORMANCE STUDY OF INGAAS/INALAS/INP MODFETS ON HETEROSTRUCTURES GROWN BY OMVPE AND MBE 4

PERFORMANCE STUDY OF INGAAS/INALAS/INP MODFETS ON HETEROSTRU...

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4TH INTERNATIONAL CONF ON INDIUM PHOSPHIDE AND RELATED MATERIALS

作者： ADESIDA, I TONG, M NUMMILA, K KETTERSON, AA AINA, L MATTINGLY, M Center for Compound Semiconductor Microelectronics Coordinated Science Laboratory Department of Electrical and Computer Engineering University of Illinois Urbana-Champaign 61801 IL United States Allied-Signal Aerospace Company 9140 Old Annapolis Road Columbia 21045 MD United States COMSAT Clarksburg MD United States

ISBN: (纸本)0780305221

Devices fabricated in InAlAs/InGaAs/InP heterostructures have demonstrated superior performance in comparison with GaAs-based heterostructures (1). In particular, InAlAs/InGaAs/InP modulation-doped field effect transistors (MODFETs) with submicron gates have demonstrated higher current drive, higher gain, and better frquency response than their corresponding GaAs-based MODFETs. This advantage is attributed to superior material properties in the form of larger conduction band discontinuity, higher room temperature electron mobility, and higher effective electron velocity. To date, the materials used for realizing these high performance submicron MODFETs have been grown largely by molecular beam epitaxy (MBE). It has recently been shown that excellent InAlAsAnGaAs/InP materials can also be grown using organometallic vapor phase epitaxy (OMVPE) (2). This has led to recent reports of OMVPE-grown InGaAs-channel and InP-channel MODFETs with performances similar to those grown using MBE (3, 4). The flexibility of OMVPE in growing both InP and InGaAs in contrast with conventional MBE makes it more versatile for the realization of materials for optoelectronic integrated circuits (OEICs). In this paper, we present our results on the DC and RF characteristics of OMVPE-grown InAlAs/InGaAs/InP MODFETs (OMVPE MODFETs) as a function of gatelength. These results are compared with results reported in literature for MBE-grown InAlAs/InGaAs/InP MODFETs (MBE MODFETs). © 1992 IEEE.

关键词： Molecular beam epitaxy

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SELECTIVE WET ETCHING FOR INGAAS/INALAS/INP HETEROSTRUCTURE FIELD-EFFECT TRANSISTORS 4

SELECTIVE WET ETCHING FOR INGAAS/INALAS/INP HETEROSTRUCTURE ...

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4TH INTERNATIONAL CONF ON INDIUM PHOSPHIDE AND RELATED MATERIALS

作者： TONG, M KETTERSON, AA NUMMILA, K ADESIDA, I AINA, L MATTINGLY, M Center for Compound Semiconductor Microelectronics Coordinated Science Laboratory Department of Electrical and Computer Engineering University of Illinois Urbana-Champaign 61801 IL United States Allied-Signal Aerospace Company 9140 Old Annapolis Road Columbia 21045 MD United States COMSAT Clarksburg MD United States

ISBN: (纸本)0780305221

The fabrication procedure of heterostructure field-effect transistors (HFETs) such as modulation-doped field-effect transistors (MODFETs) typically includes two important etching steps. The first is the mesa etch for device isolation, and the second is the gate recess where the cap layer is removed to expose the underlying layer for the Schottky gate formation. The gate recess is also used to achieve the desired drain saturation current. Both etching steps require good etch depth control, although, the control needed for the mesa process is not as critical as that for the gate recess. However, the mesa should not be overetched since metal-gate discontinuity due to breakage can occur at the mesa edge, especially for devices with nanometerdimension gate lengths. It has been shown by Tiwari (1) that excellent etch depth control is imperative in the gate recess process for short-gate-length MODFETs in order to achieve uniform threshold voltages which in turn is essential to the realization of high performance integrated circuits. Therefore, a good selectivity in the etching of the cap layer with respect to the underlying high band-gap layer is required in the fabrication of HFETs. © 1992 IEEE.

关键词： Drain current

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Electrical and Structural Properties of Cobalt Annealed on Silicon-Germanium Epilayers

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MRS Online Proceedings Library 1992年第1期281卷 647-652页

作者： G. Sarcona F. Lin M. K. Hatalis A. F. Cserhati Eva Austin D. W. Greve Dept. of Electrical Engineering and Computer Science Sherman- Fairchild Center for Solid-State Studies Lehigh University Bethlehem Allied Signal Aerospace Co. ATC Columbia Dept. of Electrical and Computer Engineering Carnegie-Mellon University Pittsburgh

The structural and electrical properties of cobalt annealed on heteroepitaxial, strained-layer silicon-germanium were studied by transmission electron microscopy, four-point-probe and four-terminal resistor resistivity measurements, and junction diodes. The I50nm thick epitaxial p-Si0.87Ge0.13 was grown by UHV-CVD at 590r.C. Cobalt was deposited by DC magnetron sputtering. The cobalt was rapid-thermally annealed at various temperatures in forming gas. The cobalt film and the SiGe layer reacted, as illustrated by changes in their film thicknesses, and increased interfacial roughness. The roughness and reacted-film thickness increased with increasing temperature. The sheet resistances of the samples were dependant on the anneal temperature and time. Films formed by annealing at 700r.C, 3 min, were 80nm thick, and had 2.8Ω/sq sheet resistivity, corresponding to 20µΩ-cm resistivity. The contact was ohmic, with contact resistivity of l.6×-10-4Ω-cm2. SiGe/ Si heterojunction diodes contacted by the reacted film, containing Co, Si, and Ge, were compared to diodes contacted by aluminum.

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Selective wet etching for InGaAs/InAlAs/InP heterostructure field-effect transistors

Selective wet etching for InGaAs/InAlAs/InP heterostructure ...

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Indium Phosphide and Related Materials Conference

作者： M. Tong A.A. Ketterson K. Nummila I. Adesida L. Aina M. Mattingly Center for Compound Semiconductor Microelectronics Coordinated Science Laboratory and Department of Electrical and Computer Engineering University of Illinois Urbana-Champaign IL USA Allied Signal Aerospace Company Columbia MD USA

The etching characteristics of InAlAs, InGaAs, and InP in citric acid/H/sub 2/O/sub 2/ solutions, and their applications to the fabrication of InAlAs/InGaAs/InP MODFETs are reported. High selectivities of up to 500 and 187 were obtained for InGaAs over InP and InAlAs over InP, respectively. Selectivity values ranging from 2.5 to 25 were achieved for InGaAs over InAlAs with citric acid/H/sub 2/O/sub 2/ solution ratio from 10 to 1. The activation energies for these materials and the etch profiles for a InGaAs/InAlAs/InP MODFET structure are reported. Citric acid/H/sub 2/O/sub 2/ solutions of appropriate ratios have been applied to both mesa etching and gate recessing with good results. These solutions may also be extended to the fabrication of InAlAs/InGaAs and InP/InGaAs heterojunction bipolar transistors.< >

关键词： Wet etching Indium gallium arsenide Indium compounds Indium phosphide HEMTs Fabrication Epitaxial layers MODFET integrated circuits Gallium arsenide Dry etching

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Performance study of InGaAs/InAlAs/InP MODFETs on heterostructures grown by OMVPE and MBE

Performance study of InGaAs/InAlAs/InP MODFETs on heterostru...

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Indium Phosphide and Related Materials Conference

作者： I. Adesida M. Tong K. Nummila A.A. Ketterson L. Aina M. Mattingly Center for Compound Semiconductor Microelectronics Coordinated Science Laboratory and Department of Electrical and Computer Engineering University of Illinois Urbana-Champaign IL USA Allied Signal Aerospace Company Columbia MD USA

The authors have fabricated and characterized MODFETs on OMVPE (organometallic vapor-phase epitaxy)-grown InAlAs/InGaAs/InP heterostructures. Excellent DC and RF characteristics were obtained. Extrinsic DC transconductance as high as 1020 mS/mm and a unity current gain cut-off frequency, f/sub T/, of 114 GHz were obtained for devices with 0.27- mu m gate-length. An effective saturation velocity of 2.0*10/sup 7/ cm/s was obtained for these devices. These results are shown to be comparable to the best results reported in the literature for MODFETs fabricated in MBE (molecular-beam epitaxy)-grown heterostructures.< >

关键词： Indium gallium arsenide Indium compounds Indium phosphide HEMTs Molecular beam epitaxial growth MODFET integrated circuits MODFET circuits Electron mobility Conducting materials Gold

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A fully Sinc‐Galerkin method for Euler–Bernoulli beam models

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Numerical Methods for Partial Differential Equations 1992年第2期8卷 171-202页

作者： Smith, Ralph C. Bowers, Kenneth L. Lund, John Institute for Computer Applications in Science and Engineering NASA Langley Research Center Hampton Virginia 23665 United States Department of Mathematical Sciences Montana State University Bozeman Montana 59717 United States

A fully Sinc‐Galerkin method in both space and time is presented for fourth‐order time‐dependent partial differential equations with fixed and cantilever boundary conditions. The sine discretizations for the second‐order temporal problem and the fourth‐order spatial problems are presented. Alternate formulations for variable parameter fourth‐order problems are given, which prove to be especially useful when applying the forward techniques of this article to parameter recovery problems. The discrete system that corresponds to the time‐dependent partial differential equations of interest are then formulated. Computational issues are discussed and an accurate and efficient algorithm for solving the resulting matrix system is outlined. Numerical results that highlight the method are given for problems with both analytic and singular solutions as well as fixed and cantilever boundary conditions. Copyright © 1992 Wiley Periodicals, Inc.

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NONLINEAR EVOLUTION OF A 2ND-MODE WAVE IN SUPERSONIC BOUNDARY-LAYERS

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APPLIED NUMERICAL MATHEMATICS 1991年第1期7卷 73-91页

作者： ERLEBACHER, G HUSSAINI, MY NASA Langley Research Center Hampton VA 23665 USA Institute for Computer Applications in Science and Engineering NASA Langley Research Center Hampton VA 23665 USA

The nonlinear time evolution of a second-mode instability in a Mach 4.5 wall-bounded flow is computed by solving the full compressible, time-dependent Navier-Stokes equations. High accuracy is achieved by using a Fourier-Chebyshev collocation algorithm. Primarily inviscid in nature, second modes are characterized by high frequency and high growth rates compared to first modes. Time evolution of growth rate as a function of distance from the plate suggests this problem is amenable to the Stuart-Watson perturbation theory as generalized by Herbert.

关键词： Aerodynamics

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A NUMERICAL-SIMULATION OF THE APPEARANCE OF CHAOS IN FINITE-LENGTH TAYLOR-COUETTE FLOW

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APPLIED NUMERICAL MATHEMATICS 1991年第1期7卷 41-71页

作者： STREETT, CL HUSSAINI, MY NASA Langley Research Center Hampton VA 23665 USA Institute for Computer Applications in Science and Engineering NASA Langley Research Center Hampton VA 23665 USA

Taylor-Couette flow, the shear-driven flow between concentric cylinders, exhibits a wide variety of instabilities and modal changes, especially for the case of finite length to gap ratio. The numerical simulations presented here capture many of the experimentally observed features, including the moderately high Reynolds number regime in which temporally aperiodic behavior is seen. The exponential decay of the temporal frequency spectrum of these modes in the simulations indicate such flows possess a low-order chaotic character. In this paper, the spectral collocation methods used in this study are described, select axisymmetric simulations are reviewed, and initial results from three-dimensional unsteady simulations are presented.

关键词： Flow of Fluids

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TURBULENT-FLOW CALCULATIONS USING UNSTRUCTURED AND ADAPTIVE MESHES

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INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS 1991年第9期13卷 1131-1152页

作者： MAVRIPLIS, DJ Institute for Computer Applications in Science and Engineering ICASE Mail Stop 132C NASA Langley Research Center Hampton VA 23665 U.S.A.

A method of efficiently computing turbulent compressible flow over complex two-dimensional configurations is presented. The method makes use of fully unstructured meshes throughout the entire flow field, thus enabling the treatment of arbitrarily complex geometries and the use of adaptive meshing techniques throughout both viscous and inviscid regions of the flow field. Mesh generation is based on a locally mapped Delaunay technique in order to generate unstructured meshes with highly stretched elements in the viscous regions. The flow equations are discretized using a finite element Navier-Stokes solver, and rapid convergence to steady state is achieved using an unstructured multigrid algorithm, Turbulence modelling is performed using an inexpensive algebraic model, implemented for use on unstructured and adaptive meshes. Compressible turbulent flow solutions about multiple-element aerofoil geometries are computed and compared with experimental data.

关键词： TURBULENT NAVIER-STOKES UNSTRUCTURED ADAPTIVE

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