Electrical and Computer Engineering Commons^™

Using Spreadsheets To Teach Problem Solving In A First Year Class, A. John Boye, P. F. Williams, Rodney J. Soukup

P. F. (Paul Frazer) Williams Publications

The “problem solving” portion of a two semester first year electrical engineering course is described. This course makes use of personal computers and spreadsheets to try to improve students’ problem solving skills. The goal is to give students a better understanding of engineering concepts and not just mathematical details. In addition to describing the course contents, a brief review of the rationale that was used in selecting the hardware and software used in the course is also given.

Acuta The Association For Telecommunications Professionals In Higher Educations Presidents

ACUTA: Other Publications

PATRICIA A. SEARLES

1993-1994

RANDAL R. COLLETT

1994-1995

DAVID E. O’NEILL

1995-1996

DR. JAMES S. CROSS

1996-1997

MARGARET L. MILONE

1997-1998

ANTHONY R. TANZI

2000-2001

MAUREEN D. TRIMM

2001-2002

JEANNE JANSENIUS

2002-2003

WALTER L. CZERNIAK

2003-2004

TAMARA J. CLOSS

2004-2005

PATRICIA H. TODUS

2005-2006

CARMINE R. PISCOPO

2006-2007

WALTER MAGNUSSEN

2007-2008

CORINNE HOCH

2008-2009

HARVEY L. BUCHANAN

2009-2010

MATTHEW ARTHUR

2010-2011

JOSEPH HARRINGTON

2011-2012

A Very Lmportant Message From The Board.......

ACUTA: Other Publications

All elected Directors-at-Large must be primary or associate representatives of an Institutional Member.

Elected Directors-at-Large will serve for a term of two (2) years.

An elected Director-at-Large may serve a maximum of two (2) consecutive terms.

Two elected Directors-at-Large will be elected annually by mail ballot. The two candidates receiving the greatest number of votes will be declared to have been elected.

Elected Directors-at-Large will begin their terms of office at the close of the Annual Conference.

In the events of the death, resignation or inability (for any reason) of any elected Director-at-Large to complete their term of Office, the …

Fuzzy Logic Applied To Adaptive Kalman Filtering, Marlys Rae Remus

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

The Kalman filter provides an effective means of estimating the state of a system from noisy measurements given that the system parameters are completely specified. The innovations sequence for a properly specified Kalman filter will be a zero-mean white noise process. However, when the system parameters change with time the Kalman filter will need to be adapted to compensate for the changes. Traditionally this has been accomplished by using nonlinear filtering, parallel Kalman filtering and covariance matching techniques. These methods have produced good results at the expense of large amounts of computational time. Necessary changes in the system parameters become …

An Optical Technique For Measurement Of Semiconductor Surface Electric Fields, Harshad P. Sardesai, William C. Nunnally

P. F. (Paul Frazer) Williams Publications

We present an optical technique for the measurement of semiconductor surface electric fields. The measurement technique uses the Kerr electro-optic effect in nitrobenzene, a phase sensitive interferometer, and associated data acquisition units to measure the surface electric fields between the contacts of a planar semiconductor device. This technique was used to measure the surface fields on silicon devices used in pulsed power applications, but has the potential for use as an electric field probe for any device having high surface electric fields, both pulsed and dc. The measurement technique showed a temporal resolution of 100 ns, which can be easily …

Graded Refractive Index Silicon Oxynitride Thin Film Characterized By Spectroscopic Ellipsometry, Paul G. Snyder, Yi-Ming Xiong, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

A graded refractive index silicon oxynitride (SiO_xN_y) thin film was prepared on a silicon substrate by ion assisted deposition. Spectroscopic ellipsometry (SE) was used to optically analyze the film. The measured SE spectra (2500-8200 Å) were analyzed with several fitting models, whose construction was based on an Auger depth profile of the film. In each model, the optical response of SiO_xN_y was described using the Bruggeman effective medium approximation, by modeling it as a physical mixture of two distinct phases: silicon dioxide and silicon nitride. Grading was modeled by varying the silicon nitride …

Silicon Nitride/Silicon Oxynitrid/Silicon Dioxide Thin Film Multilayer Characterized By Variable Angle Spectroscopic Ellipsometry, Yi-Ming Xiong, Paul G. Snyder, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

Variable angle spectroscopic ellipsometry (VASE) was used to nondestructively characterize a silicon nitride (Si₃N₄)/silicon oxynitride (SiO_xN_y)/silicon dioxide (SiO₂) thin film multilayer structure, in which Si₃N₃ and SiO_xN_y layers were deposited by plasma enhanced chemical vapor deposition and low-pressure chemical vapor deposition, respectively. The measured VASE spectra (3500-8200 Å) were analyzed with an appropriate multilayer fitting model, in which the SiO_xN_y layer was modeled. in the Bruggeman effective medium approximation (EMA), to be a physical mixture of two distinct phases, SiO_{2 …}

Model-Based Target Recognition Using Laser Radar Imagery, Robert Y. Li

Department of Electrical and Computer Engineering: Faculty Publications

Autonomous target recognition can be assisted by using CO2 laser radar data. Of these data, range data provide 3-D geometric information and Doppler data boundaries of moving targets. A powerful 3-D feature extraction algorithm based on the Hough transform is used to obtain the orientations and dimensions of the target. This information is then utilized by an inference procedure that recognizes targets based on the available evidence from the sensory data. The experimental results using actual laser radar imagery are successful and the procedure can be used for the future development of a model-based system for target recognition.

Acuta: A Case For Change

ACUTA: Other Publications

In This Issue

Preface

Executive Summary

Societal Trends

The Information Age

The University of the 21st Century

Implications for Telecommunications Administrators

Temperature Dependence Of Optical Properties Of Gaas, Huade Yao, Paul G. Snyder, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

Pseudodielectric functions (ε) = (ε₁) + i (ε₂) of GaAs were measured by spectroscopic ellipsometry (SE), in the range of 1.W.45 eV, at temperatures from room temperature (RT) to ~610 ° C. A very clean, smooth surface was obtained by first growing an epitaxial layer of GaAs on a GaAs substrate and immediately capping it with a protective layer of arsenic. The cap prevented surface oxidation during transport to the measurement chamber, where it was evaporated under ultrahigh vacuum at ~350 °C. Room-temperature SE results from this surface are in good agreement with those in the …

Optical And Magneto-Optical Characterization Of Tbfeco Thin Films In Trilayer Structures, William A. Mcgahan, Ping He, Liang-Yao Chen, Sal Bonafede, John A. Woollam, F. Sequeda, T. Mcdaniel, H. Do

Department of Electrical and Computer Engineering: Faculty Publications

A series of TbFeCo films ranging in thickness from 100 to 800 Å have been deposited in trilayer structures on silicon wafer substrates, with S₃N₄ being employed as the dielectric material. These films have been characterized both optically and magneto-optically by variable angle of incidence spectroscopic ellipsometry, normal angle of incidence) reflectometry, and normal angle of incidence Kerr spectroscopy. From these measurements, the optical constants n and k have been determined for the TbFeCo films, as well as the magneto-optical constants Ql and Q2. Results are presented that demonstrate the lack of dependence of these …

Magneto-Optical Kerr Effect And Perpendicular Magnetic Anisotropy Of Evaporated And Sputtered Co/Pt Multilayer Structures, Ping He, William A. Mcgahan, John A. Woollam, F. Sequeda, T. Mcdaniel, H. Do

Department of Electrical and Computer Engineering: Faculty Publications

Thin and ultrathin Co/Pt multilayered structures have been prepared on glass substrates by electron-beam evaporation at room temperature and by sputtering at various substrate temperatures and sputtering pressures. Perpendicular magnetic anisotropy was found in samples with Co/Pt bilayer thicknesses near 3 Å/l0 Å and total thicknesses of the layer stack of no greater than 300 Å. X-ray diffraction was performed on the samples to determine layer spacing and integrity, and possible crystallinity of films. Crystalline structures in the interface between the Co and Pt layers were found and identified. The effects of sputtering parameters, such as pressure and substrate temperature, …

Forming Fine Particles, Dennis R. Alexander

Department of Electrical and Computer Engineering: Faculty Publications

To alter feedstock material, the material is exposed to laser radiation applied at a selected angle of incidence, intensity and wavelength related to the refractive index of the feedstock material. Fine uniform particles may be formed through vapor explosion and/or plasma formation and used by this method to coat surfaces, such as with paint or adhesive or to suply uniform small particles to a heat engine. Moreover, moving materials such as a column of liquid may be subjected to high internal pressure and temperature for creating physical and chemical changes.

What To Look For And Why When Buying A Telecommunications Switch

ACUTA: Other Publications

There are three characteristics of institutions of higher education that have a strong

impact on telecommunications:

. Campus Environment

. Multiple Service Populations

. Limited Budgets

Each characteristic translates into requirements for an effective telecommunication

system.

To Serve the Campus Environment

A campus is usually the first image associated with the word "college" or "university." Typically, institutions of higher education are housed in several buildings which may be fairly close together, or spread over some distance, perhaps reaching across a city or even a state.

To serve the campus user, a system must provide feature transparency, regardless of location. Small …

Study Of Ingaas-Based Modulation Doped Field Effect Transistor Structures Using Variable-Angle Spectroscopic Ellipsometry, S. A. Alterovitz, R. M. Sieg, H. D. Yao, Paul G. Snyder, John A. Woollam, J. Pamulapati, P. K. Bhattacharya, P. A. P. A. Sekula-Moise

John A. Woollam Publications

Variable-angle spectroscopic ellipsometry was used to estimate the thicknesses of all layers within the optical penetration depth of InCaAs-based modulation doped field effect transistor structures. Strained and unstrained InGaAs channels were made by molecular beam epitaxy (MBE) on InP substrates and by metal-organic chemical vapor deposition on GaAs substrates. In most cases. ellipsometrically determined thicknesses were within 10% of the growth-calibration results. The MBE-made InCaAs strained layers showed large strain effects, indicating a probable shift in the critical points of their dielectric function toward the InP lattice-matched concentration.

Surface Flashover Of Silicon, Frank E. Peterkin, Tim Ridolfi, Lonnie L. Buresh, Brian J. Hankla, D. K. Scott, P. F. Williams, William C. Nunnally, B. L. Thomas

P. F. (Paul Frazer) Williams Publications

The development of high-voltage semiconductor devices has been hampered by the occurrence of flashover at the surface of the semiconductor. The physical mechanisms responsible for this phenomenon are not understood. We present new empirical information which clarifies the processes responsible for surface flashover in a vacuum ambient by showing clearly that in flashover current flows primarily inside the semiconductor surface rather than in the ambient. This observation is in fundamental disagreement with the standard model for vacuum flashover of insulator surfaces.

Modeling AiXGa1-XAs Optical Constants As Functions Of Composition, Paul G. Snyder, John A. Woollam, Samuel A. Alterovitz, Blaine D. Johs

Department of Electrical and Computer Engineering: Faculty Publications

Three models for the dielectric function ε_x (hv) of Ag_xGa1_1-xAs are reviewed. All are based on measured optical constants at discrete compositions. The validity of each mode1 near critical pint energies, and otherwise, is evaluated. Only the energy-shift model is appropriate over the entire available spectrum ( 1.5-6.0 eV), including the band-gap (E₀) region.

Ellipsometric Analysis Of Computer Disk Structures, Ping He, Bhola N. De, Laing-Yao Chen, Yong Zhao, John A. Woollam, Mark Miller, Edward Simpson

Department of Electrical and Computer Engineering: Faculty Publications

Abstract: We have used variable angle spectroscopic ellipsometry (VASE) to analyze the materials surfaces and interfaces in multilayer sputtered media computer disks. Specifically, the system C/CoNiCr/Cr/NiP/Al has been investigated for layer thicknesses, interfacial and surface roughness, and radial and circumferential uniformity. By first characterizing the Cr/NiP/Al then CoNiCr/Cr/NiP/Al structures, we were able to fully characterize the complete disk structure. The interface width between the carbon layer and CoNiCr magnetic layer was determined to be approximately 260 Å. This is reasonable considering typical surface roughness present on magnetic disks, and that the carbon “fills” in this surface roughness. VASE is a …

Pulsed Laser Annealing Of Gaas Implanted With Se And Si, Andrzej Rys, Yanan Shieh, Alvin Compann, Huade Yao, Ajit Bhat

Department of Electrical and Computer Engineering: Faculty Publications

Carrier activation and mobility were studied by Raman spectroscopy and the Hall effect in pulsed laser annealed samples of GaAs implanted with doses of Si and Se from 2.2. x 10¹² to 6.0 x 10¹⁴ cm^-2. The samples were annealed using a pulsed XeCl excimer laser ( = 308 nm) and a pulsed dye laser (=728 nm) with energy densities from 0.06 to 0.9 J/cm² and pulse durations of about 10 ns. Very high carrier concentrations of 3 x 10¹⁹ and 1.5 x 10¹⁹ cm^-3 were obtained for the best n-type GaAs …

Major Project Management: The Yale Telecommunications Project

ACUTA: Other Publications

Back in the good old days, when the telephone business was simpler and Saturday night television was worth watching, I can remember Ted Knight the newsman (remember him on The Mary Tyler Moore Show?) looking off into some imagined horizon in the newsroom when asked how he happened to come to his current position. With head cocked upward and his hand clutching his right lapel, he'd start in his deepest, most pompous voice: “lt all started in a small, 5,000-watt radio station..." Around here it a!! started with a 12,000-line, decade-old Centrex system and a new hospital building going up …

Enhanced Magneto-Optic Kerr Effects In Thin Magnetic/Metallic Layered Structures, William A. Mcgahan, Liang-Yao Chen, Z. S. Shan, David J. Sellmyer, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

Enhanced Kerr rotation spectra are measured in thin magnetic layers on silver. Also, variable angle of incidence spectroscopic ellipsometry is employed to measure the optical dielectric function of both the thin magnetic layer and the underlying thick silver layer. These results are explained quantitatively using the electromagnetic theory for reflection of light from multiple layers of isotropic and gyrotropic materials.

Ellipsometric Study Of Al2O3/Ag/Si And Sio2/Ag/Quartz Ashed In An Oxygen Plasma, Bhola N. De, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

Using monolayer-sensitive variable angle of incidence spectroscopic ellipsometry, the silver oxide growth on a silver mirror, coated with an Al₂ O₃ or SiO₂ protective layer, was investigated. The oxidation was done in a pure oxygen plasma asher. The resulting silver oxide growth was monitored accurately as a function of exposure time in the plasma asher. It was found that silver was converted to silver oxide under the protective coating, during ashing of a sample. The optical constants of a dense silver oxide thin film, created by oxidizing in the asher, were also measured.

Triggering In Trigatron Spark Gaps: A Fundamental Study, P. F. Williams, F. E. Peterkin

P. F. (Paul Frazer) Williams Publications

The trigatron has been in widespread use as a demand-triggered, high-voltage switch for more than 40 years. In spite of the popularity and maturity of the technology, there persists an uncertainty over the basic physical mechanism(s) responsible for triggering breakdown in the devices. We present the results of an empirical study of trigatrons that demonstrates that breakdown is initiated by a streamer launched from the trigger pin, independent of the trigger spark. We compare our results with those of previous workers, and discuss the generality of our conclusions.

Radio-Frequency Plasma Chemical Vapor Deposition Growth Of Diamond, Duane E. Meyer, Rodney O. Dillon, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

Plasma chemical vapor deposition (CVD) at 13.56 MHz has been used to produce diamond particles in two different inductively coupled systems with a mixture of methane and hydrogen. The effect of a diamond-like carbon (DLC) overcoating on silicon, niobium, and stainless-steel substrates has been investigated and in the case of silicon has been found to enhance particle formation as compared to uncoated polished silicon. In addition the use of carbon monoxide in hydrogen has been found to produce well-defined individual faceted particles as well as polycrystalline films on quartz and DLC coated silicon substrates. Plasma CVD is a competitive approach …

Optical- And Magnets-Optical Measurements Using A Variable Angle Of Incidence Spectroscopic Ellipsometer: Application To Dyco Multilayer, William A. Mcgahan, Z. S. Shan, Alan M. Massengale, Thomas E. Tiwald

Department of Electrical and Computer Engineering: Faculty Publications

We have extended the technique of variable angle spectroscopic ellipsometry to measurement of the magneto-optical effects as a function of wavelength and angle of incidence and field strength. Results on DyCo multilayers are reported.

Optical-Absorption Edge And Disorder Effects In Hydrogenated Amorphous Diamondlike Carbon Films, T. Datta, John A. Woollam, W. Notohamiprodjo

Department of Electrical and Computer Engineering: Faculty Publications

Optical absorption (~1–5 eV) in rf-deposited hydrogenated (20–40 at. %) amorphous “diamondlike” carbon films has been studied as a function of heat treatment. For E >~ 2.5 eV a Tauc behavior is exhibited. Optical band gaps E_g are E₀, the width of the tail, is quantitatively explained in terms of the annealing temperature T_H. Increasing T_H (<700 >K) reduces the hydrogen content, lowers E_g, and appears to harden the films. E_g is determined to be a linear function of E₀. Additional analysis was performed in terms of a divergence …

Theoretical Model For The Images Formed By A Spherical Particle In A Coherent Imaging System: Comparison, Scott Alan Schaub, D. R. Alexander, J. P. Barton

Department of Electrical and Computer Engineering: Faculty Publications

A simple theoretical model is presented that allows calculation of the image produced by a spherical absorbing particle illuminated by monochromatic, coherent laser light. Results presented in this paper are restricted to a singe-lens imaging system, although generalization to more complex imaging system configurations would be straightfoward. The method uses classic Lorenz-Mie scattering theory to obtain the electromagnetic field external to an absorbing spherical particle and a Fourier optics approach to calculate the intensities in the image plane. Experimental results evaluating focus characteristics are examined for 50 um diameter water droplets using an N2 laser imaging system in conjunction with …

Assessment Of Squirrel-Caused Power Outages, J. Chris Hamilton, Ron J. Johnson, Ronald M. Case, Michael W. Riley

School of Natural Resources: Faculty Publications

Squirrel-caused power outages in Lincoln and Omaha, Nebraska, were evaluated by examining company power outage reports and by consulting with power company representatives. Reports showed that squirrel-caused outages at pole-mounted transformers were most prevalent during May, June, and October (48% of total) and between 1 and 4 h after sunrise (38%), patterns that coincide with squirrel dispersal or morning activity periods. In Lincoln, 1980 and 1981, squirrels caused 177 outages per year, which was 24% of all outages and 90% of animal-caused outages. Estimated minimum annual costs were $23 364 for repairs, public relations, and lost revenue while meters were …

Generalized Model For The Optical Absorption Edge In A-Si:H, T. Datta, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

We have reanalyzed the published optical absorption coefficient data for a-Si:H and introduced a divergence temperature, a new concept in the physics of these materials.

Variable Angle Spectroscopic Magneto-Optics And Ellipsometry: Application To Dyco Multilayers, Thomas E. Tiwald, William A. Mcgahan, Z. S. Shan, Alan M. Massengale, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

The purpose of this paper is twofold. First, we describe the adaptation of a variable angle spectroscopic ellipsometer (VASE) to magneto-optic measurements covering 3000–8000 Å, and 0 to ±8 kOe. Second, we describe application of VASE to determine Kerr rotation and ellipticity for a series of Dy/Co multilayers prepared by sputter deposition. We report spectroscopic ellipsometric and Kerr effect results for samples exhibiting perpendicular magnetic anisotropy, since these are relevant as magneto-optic recording media.