Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons™

Open Access. Powered by Scholars. Published by Universities.®

Wright State University

Discipline
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 3721 - 3750 of 3840

Full-Text Articles in Physical Sciences and Mathematics

Review Of Hall Effect And Magnetoresistance Measurements In Gaas Materials And Devices, David C. Look Jan 1990

Review Of Hall Effect And Magnetoresistance Measurements In Gaas Materials And Devices, David C. Look

Physics Faculty Publications

The use of magnetic fields in the electrical characterization of semiconductor materials is familiar to everyone in the form of Hall‐effect measurements. However, there is another magnetic‐field‐based phenomenon, magnetoresistance (MR), which is highly useful but not nearly so familiar to the majority of workers. One of the unique features of MR measurements is their applicability to common device structures, in particular, field‐effect transistors (FETs) and contact‐resistance patterns. We will show how channel mobility information can be extracted from the MR data in metal‐semiconductor FETs (MESFETs) and modulation‐doped heterostructure FETs (MODFETs), and also how the material under ohmic contacts can be …

Go to article

Transition Probabilities And Franck-Condon Factors For The Second Negative Band System Of O2+, Jane L. Fox, Alexander Dalgarno Jan 1990

Transition Probabilities And Franck-Condon Factors For The Second Negative Band System Of O2+, Jane L. Fox, Alexander Dalgarno

Physics Faculty Publications

Transition probabilities for the second negative band system of O2+ are computed using the dipole transition moment presented by Wetmore et al. [1984]. Vibrational levels υ″ = 0 − 54 of the X²Πg ground state and υ′ = 0 − 33 of the excited A²Πu state are included. Franck-Condon factors for ionization-excitation of O2 (X³Σg−; υ = 0 − 25) to O2+(A²Πu;υ′ = 0 − 33) are also presented.

Go to article

A Signature Of Auroral Precipitation In The Nightside Ionosphere Of Venus, Jane L. Fox, H. A. Taylor Jr. Jan 1990

A Signature Of Auroral Precipitation In The Nightside Ionosphere Of Venus, Jane L. Fox, H. A. Taylor Jr.

Physics Faculty Publications

We show here that the densities of mass-28 ions measured by the Pioneer Venus Orbiter ion mass spectrometer (OIMS) on the nightside of Venus are highly variable and show little correlation with the values of the O+ densities. We have determined the total production rates of mass-28 ions in the chemical equilibrium region and find that this production rate cannot be explained by known chemical production reactions. We propose that the “excess” production is due to precipitation of electrons into the nightside thermosphere.

Go to article

Theoretical Intensity-Dependent Response Of Nonlinear Periodic Structures, Paul A. Gohman, Gust Bambakidis, Robert J. Spry Jan 1990

Theoretical Intensity-Dependent Response Of Nonlinear Periodic Structures, Paul A. Gohman, Gust Bambakidis, Robert J. Spry

Physics Faculty Publications

We have modeled the response of a nonlinear periodic structure by means of the Abelés 2×2 matrix method. Our structure differs from the usual rejection‐band filter designs, in that we have chosen the filter elements to be index matched in the absence of radiation, providing a rejection band that both grows and shifts as a function of incident intensity. The intensity output function of the model not only directly demonstrates optical bistability, but also limiting, switching, self‐pulsing, and chaos.

Go to article

In Situ Hall-Effect System For Real-Time Electron-Irradiation Studies, B. S. Ziebro, David C. Look, Joseph W. Hemsky, J. Rice Jan 1990

In Situ Hall-Effect System For Real-Time Electron-Irradiation Studies, B. S. Ziebro, David C. Look, Joseph W. Hemsky, J. Rice

Physics Faculty Publications

A unique system capable of taking in situ Hall‐effect measurements during electron irradiation has been developed. The key element is a small, powerful rare‐earth magnet. Measurements can be taken while the electron beam is on, resulting in a considerable time savings and eliminating problems associated with mounting and demounting the sample. High resolution electron concentration and mobility versus fluence data are quickly and easily obtained, making possible detailed defect production rate studies as functions of energy and flux.

Go to article

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, January 1990, College Of Engineering And Computer Science, Wright State University Jan 1990

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, January 1990, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A fourteen page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

Go to article

Attribute Relationships: An Impediment In Automating Schema Integration, Amit P. Sheth, Sunit K. Gala Dec 1989

Attribute Relationships: An Impediment In Automating Schema Integration, Amit P. Sheth, Sunit K. Gala

Kno.e.sis Publications

Success in schema integration depends on understanding the semantics of schema components (e.g., entity sets, relationship sets, attributes), and the ability to capture and reason about these semantics. An important objective of our work on schema integration is to automate the reasoning as much as possible, and when not possible, depend on the human input and guidance. A key results of comparing the semantics associated with schema objects is that of determining attribute relationship. Once attribute relationships are determined, the task of object class(e.g., entity sets and relationship sets) integration becomes simpler and can e automated to a great extent. …

Go to article

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, November 1989, College Of Engineering And Computer Science, Wright State University Nov 1989

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, November 1989, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A sixteen page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

Go to article

Deviations From Bulk Transport Measurements In Semi-Insulating Gaas, N. C. Halder, David C. Look Nov 1989

Deviations From Bulk Transport Measurements In Semi-Insulating Gaas, N. C. Halder, David C. Look

Physics Faculty Publications

Because of the high bulk resistivity of semi‐insulating GaAs, surface or near‐surface effects can change the apparent magnitudes of resistivity, mobility, and carrier concentration. We consider the following causes: (1) above‐surface conduction, such as that due to impurities in a porous oxide; (2) subsurface conduction, due to sawing and polishing damage; (3) tunneling conduction in surface states; and (4) changes in near‐surface conduction due to the modification of surface potential by surface states or absorbates. The most important of these effects appear to be subsurface damage and surface potential changes.

Go to article

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, October 1989, College Of Engineering And Computer Science, Wright State University Oct 1989

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, October 1989, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A fourteen page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

Go to article

Student Fact Book, Fall 1989, Wright State University 25 Years Vision Unlimited, Office Of Student Information Systems, Wright State University Oct 1989

Student Fact Book, Fall 1989, Wright State University 25 Years Vision Unlimited, Office Of Student Information Systems, Wright State University

Wright State University Student Fact Books

The student fact book has general demographic information on all students enrolled at Wright State University for Fall Quarter, 1989.

Go to article

Hall-Effect Depletion Corrections In Ion-Implanted Samples: Si29 In Gaas, David C. Look Sep 1989

Hall-Effect Depletion Corrections In Ion-Implanted Samples: Si29 In Gaas, David C. Look

Physics Faculty Publications

The sheet free‐carrier concentration in a thin, conducting layer on an insulating substrate is lower than the net, sheet‐dopant concentration because of free‐carrier depletion in the surface and interface regions. Here we develop an algorithm to give the true, net sheet‐donor concentration from the measured sheet‐Hall concentration under the assumption of a Gaussian donor profile, which is usually sufficiently accurate for ion‐implanted samples. Correction curves are generated for Si29 ions implanted into GaAs at energies of 60, 100, 130, 150, and 200 keV, and at doses of 1×1011–2×1014 ions/cm2. Also, the …

Go to article

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, September 1989, College Of Engineering And Computer Science, Wright State University Sep 1989

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, September 1989, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A twelve page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

Go to article

Silicon Crystallite Formation In Ion-Implanted Quartz, U. B. Ramabadran, H. E. Jackson, Gary C. Farlow Sep 1989

Silicon Crystallite Formation In Ion-Implanted Quartz, U. B. Ramabadran, H. E. Jackson, Gary C. Farlow

Physics Faculty Publications

Rapid thermally annealed silicon‐implanted x‐cut α‐quartz samples have been examined by Rutherford backscattering and Raman microprobe spectroscopy. The data indicate that the silicon has diffused at 1200 °C to form a buried layer of crystallites of size 1–10 μm. The crystallites are preferentially oriented and under substantial stress.

Go to article

Spatial Critical Points Of Solutions Of A One-Dimensional Nonlinear Parabolic Problem, Larry Turyn Aug 1989

Spatial Critical Points Of Solutions Of A One-Dimensional Nonlinear Parabolic Problem, Larry Turyn

Mathematics and Statistics Faculty Publications

The number of spatial critical points is nonincreasing in time, for positive, analytic solutions of a scalar, nonlinear, parabolic partial differential equation in one space dimension. While proving this, we answer the question: What happens to a critical point which loses simplicity?

Go to article

Uniformity Of 3-In, Semi-Insulating, Vertical-Gradient-Freeze Gaas Wafers, David C. Look, D. C. Walters, M. G. Mier, J. S. Sewell, J. S. Sizelove, A. Akselrad, J. E. Clemans Jul 1989

Uniformity Of 3-In, Semi-Insulating, Vertical-Gradient-Freeze Gaas Wafers, David C. Look, D. C. Walters, M. G. Mier, J. S. Sewell, J. S. Sizelove, A. Akselrad, J. E. Clemans

Physics Faculty Publications

We have evaluated the uniformity in [EL2], dislocation (or etch‐pit) density (EPD), resistivity, mobility, and carrier concentration for 3‐in., semi‐insulating GaAs wafers grown by the vertical‐gradient‐freeze (VGF) technique. Although slight W or U patterns were observed in [EL2] and EPD along the 〈110〉 directions, for the first time, nevertheless the overall uniformity was excellent, and comparable to that in the best In‐doped and whole‐boule‐annealed ingots grown by the liquid‐encapsulated Czochralski (LEC) technique. Based on results from implant‐activation studies on LEC wafers, it is estimated that the measured nonuniformities in EPD and [EL2] for the VGF wafers would contribute only about …

Go to article

Fault Tolerance In A Very Large Database System: A Strawman Analysis, Amit P. Sheth Jun 1989

Fault Tolerance In A Very Large Database System: A Strawman Analysis, Amit P. Sheth

Kno.e.sis Publications

A simple model is used to study the effect of fault-tolerance techniques and system design on system availability. A generic multiprocessor architecture is used that can be configured in different ways to study the effect of system architectures. Important parameters studied are different system architectures and hardware fault-tolerance techniques, mean time to failure of basic components, database size and distribution, interconnect capacity, etc. Quantitative analysis compares the relative effect of different parameter values. Results show that the effect of different parameter values on system availability can be very significant. System architecture, use of hardware fault tolerance (particularly mirroring), and data …

Go to article

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, May 1989, College Of Engineering And Computer Science, Wright State University May 1989

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, May 1989, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A ten page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

Go to article

Determination Of Shallow Minority-Acceptor Concentration In Multiply Doped Silicon, Gust Bambakidis, G. J. Brown Apr 1989

Determination Of Shallow Minority-Acceptor Concentration In Multiply Doped Silicon, Gust Bambakidis, G. J. Brown

Physics Faculty Publications

A method is presented, based on photothermal ionization spectroscopy (PTIS), for determining the shallow minority‐acceptor concentration in multiply doped silicon, over the concentration range 1013/cm3–1015/cm3. The method is an extension of a model developed previously for the PTIS response in a multiply doped semiconductor, which accounts for the experimentally observed change in signature, from negative to positive, of the lower‐energy lines of the deeper acceptor as the temperature is increased. It uses a calculated curve of the dependence on the shallow‐acceptor concentration of the temperature at which the change in …

Go to article

Photodissociation Of Co In The Thermosphere Of Venus, Jane L. Fox Apr 1989

Photodissociation Of Co In The Thermosphere Of Venus, Jane L. Fox

Physics Faculty Publications

Recent investigations of CO photoabsorption demonstrate that photodissociation longward of the ionization threshold at 88.5 nm occurs primarily through line absorptions rather than continuous processes. We have constructed high resolution photoabsorption cross sections for CO at rotational temperatures near 250 K from the improved data on dissociating transitions. We examine the effects of the new cross sections on the rate of solar photodissociation of CO in the thermosphere of Venus and compare the results to values obtained with the lower resolution cross sections available previously. We find that the photodissociation profile peaks slightly higher in the atmosphere and the peak …

Go to article

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, March 1989, College Of Engineering And Computer Science, Wright State University Mar 1989

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, March 1989, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A ten page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

Go to article

A New Technique For Whole-Wafer Etch-Pit Density Mapping In Gaas, David C. Look, D. C. Walters, J. S. Sewell, S. C. Dudley, M. G. Mier, J. S. Sizelove Feb 1989

A New Technique For Whole-Wafer Etch-Pit Density Mapping In Gaas, David C. Look, D. C. Walters, J. S. Sewell, S. C. Dudley, M. G. Mier, J. S. Sizelove

Physics Faculty Publications

The pits formed on an etched GaAs surface, due to the anisotropic etching around dislocations, are efficient light scatterers, and thus reduce transmission. We have derived a quantitative relationship between the fractional transmission and the etch‐pit density (EPD) and have shown that the same absorption apparatus which is commonly used to obtain a whole‐wafer [EL2] map can also be used to generate an EPD map. The technique is verified by comparing the fractional transmission with the actual EPD count at 166 points on a three‐inch, low‐pressure, liquid‐encapsulated Czochralski wafer. Also, [EL2] and EPD maps, with more than 3500 points each, …

Go to article

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, February 1989, College Of Engineering And Computer Science, Wright State University Feb 1989

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, February 1989, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A ten page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

Go to article

On The Existence And Symmetry Properties Of Finite Total Mass Solutions Of The Matukuma Equation, The Eddington Equation And Their Generalizations, Yi Li, Wei-Ming Ni Jan 1989

On The Existence And Symmetry Properties Of Finite Total Mass Solutions Of The Matukuma Equation, The Eddington Equation And Their Generalizations, Yi Li, Wei-Ming Ni

Yi Li

No abstract provided.

Go to article

On The Existence And Symmetry Properties Of Finite Total Mass Solutions Of The Matukuma Equation, The Eddington Equation And Their Generalizations, Yi Li, Wei-Ming Ni Jan 1989

On The Existence And Symmetry Properties Of Finite Total Mass Solutions Of The Matukuma Equation, The Eddington Equation And Their Generalizations, Yi Li, Wei-Ming Ni

Mathematics and Statistics Faculty Publications

No abstract provided.

Go to article

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, January 1989, College Of Engineering And Computer Science, Wright State University Jan 1989

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, January 1989, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A ten page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

Go to article

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, November 1988, College Of Engineering And Computer Science, Wright State University Nov 1988

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, November 1988, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A fourteen page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

Go to article

Transformation Based Endorsement Systems, Thomas Sudkamp Nov 1988

Transformation Based Endorsement Systems, Thomas Sudkamp

Computer Science and Engineering Faculty Publications

Evidential reasoning techniques classically represent support for a hypothesis by a numeric value or an evidential interval. The combination of support is performed by an arithmetic rule which often requires restrictions to be placed on the set of possibilities. These assumptions usually require the hypotheses to be exhausitive and mutually exclusive. Endorsement based classification systems represent support for the alternatives symbolically rather than numerically. A framework for constructing endorsement systems is presented in which transformations are defined to generate and update the knowledge base. The interaction of the knowledge base and transformations produces a non-monotonic reasoning system. Two endorsement based …

Go to article

Student Profile, Fall 1988, Wright State University, Office Of Student Information Systems, Wright State University Oct 1988

Student Profile, Fall 1988, Wright State University, Office Of Student Information Systems, Wright State University

Wright State University Student Fact Books

The student profile fact book has general demographic information on all students enrolled at Wright State University for Fall Quarter, 1988.

Go to article

Remarks On A Semilinear Elliptic Equation On Rn, Yi Li Jul 1988

Remarks On A Semilinear Elliptic Equation On Rn, Yi Li

Yi Li

No abstract provided.

Go to article

First Prev Next Last