Electrical and Computer Engineering Commons^™

Acuta 25th Annual Conference- Silver Anniversary- July 14-18, 1996- Chicago Hilton & Towers.

ACUTA: Other Publications

Registration & Hotel Information

Registration if postmarked by June 24, 1996.(Extended from June 14)

. Member Institution/Associate Member - $525. Corporate Affiliate - $525. Non-Member - $650

Registration if postmarked after June 24, 1996.

Member Institution/Associate Member - $57. Corporate Affiliate - $575 . Non-Member - $700

Hotel: Chicago Hilton & Towers

312-922-4400. Rates are $118 Single or Double. Be sure and mention the ACUTA rate! Cutoff date

for hotel is June 19,19961

Due to the popularity of this event and the Chicago destination, the hotel is full on some nights.

However, the ACUTA rate of $ll8 single/double per night …

United States Patent: System And Method For Compensating Polarization-Dependent Sensitivity Of Dispersive Optics In A Rotating Analyzer Ellipsometer System, Steven E. Green, Shakil A. Pittal, Blaine D. Johs, John A. Woollam, David W. Doerr, Reed A. Christenson

Department of Electrical and Computer Engineering: Faculty Publications

An ellipsometer system which includes a pivotal dispersive optics positioned to receive polychromatic light from an analyzer thereof, without further focusing after reflection from a substrate system, is presented. In addition, a rotating compensator, positioned between the analyzer and the dispersive optics, which serves to reduce detector element polarization dependent sensitivity to light entering thereto after it interacts with the dispersive optics, is disclosed. The method of the present invention can include application of mathematical correction factors to, for instance, substrate system characterizing PSI and DELTA values, or Fourier ALPHA and BETA coefficients.

In Situ And Ex Situ Optical Characterization Of Electro Deposited Magneto-Optic Materials, James N. Hilfiker, Darin W. Glenn, Scott W. Heckens, John A. Woollam, Kurt W. Weirman

Department of Electrical and Computer Engineering: Faculty Publications

Electrodeposition is being investigated as a novel and low-cost method to prepare magneto-optic thin film and nanostructured materials. This deposition method allows precise control over thin-film properties and permits deposition of novel magnetic geometries. Multilayers and alloys can be deposited and controlled by adjusting deposition potentials and ion concentrations in the bath. Nickel/cobalt alloys have been electrodeposited from sulfamate, sulfate, and chloride solutions onto Au substrates. The optical properties were monitored in situ with a real-time spectroscopic ellipsometer measuring simultaneously at 44 wavelengths in the 410–750 nm spectral range. In situ measurements have the advantage of determining the material microstructural …

United States Patent: System And Method For Compensating Polarization-Dependent Sensitivity Of Dispersive Optics In A Rotating Analyzer Ellipsometer System, Blaine D. Johs, Shakil A. Pittal, Steven E. Green, John A. Woollam, David W. Doerr, Reed A. Christenson

Department of Electrical and Computer Engineering: Faculty Publications

An ellipsometer system which includes a pivotal dispersive optics positioned to receive polychromatic light from an analyzer thereof, without further focusing after reflection from a substrate system, is presented. In addition, a stationary compensator, positioned between an analyzer and the dispersive optics, which serves to reduce detector element polarization dependent sensitivity to light entering thereto after it interacts with the dispersive optics, is disclosed. The use of a light fiber to carry light from a source thereof, to a polarization state generator, is also disclosed. The method of the present invention can include application of mathematical correction factors to, for …

Studies Of Thin Strained Inas, Alas, And Alsb Layers By Spectroscopic Ellipsometry, C. M. Herzinger, Paul G. Snyder, F. G. Celii, Y.-C. Kao, D. Chow, B. Johs, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

The optical constants for thin layers of strained InAs, AlAs, and AlSb have been investigated by spectroscopic ellipsometry and multi-sample analyses. These materials are important for high-speed resonant tunneling diodes in the AlAs/InAs/In_0.53Ga_0.47As and AlSb/InAs material systems. Understanding the optical properties for these thin layers is important for developing in situ growth control using spectroscopic ellipsometry. Ex situ room-temperature measurements were made on multiple samples. The resulting fitted optical constants are interpreted as apparent values because they are dependent on the fit model and sample structure. These apparent optical constants for very thin layers can be …

High-Temporal-Resolution, High-Sensitivity Imaging Of Streamers In A Long Atmospheric Pressure Gap, W. J. Yi, B. J. Hankla, P. F. Williams

P. F. (Paul Frazer) Williams Publications

We present time-resolved shutter photographs of streamers in a 13-cm gas-filled atmospheric pressure gap. The photographs show that in pure N₂, the streamers split readily in two. In mixtures containing O₂ , on the other hand, this bifurcation is substantially reduced.

Schlieren Photography Of Current Filaments In Surface-Related Breakdown Of Silicon, B. J. Hankla, P. F. Williams

P. F. (Paul Frazer) Williams Publications

We have used a modified Schlieren technique to photograph current filaments formed inside silicon during the very early stages of surface-related breakdown. We believe that the features we see are due to heating in the filamentary channel. The very rapid formation of these channels suggests that they result from streamer-like phenomena in the bulk silicon.

Surface-Related Breakdown In Silicon: Imaging Of Current Filaments In Long P+-N--N+ Structures, B. J. Hankla, P. F. Williams, G. A. Frecks, F. E. Peterkin

P. F. (Paul Frazer) Williams Publications

We present Schlieren images which show the existence and evolution of current filaments during the very early stages of surface-related breakdown inside 1 cm silicon p⁺-n^--n⁺ structures. These images confirm our previous finding that breakdown occurs in the silicon rather than in the ambient, and suggest that a streamerlike mechanism may be responsible.

Spectroscopic Ellipsometric Monitoring Of Electron Cyclotron Resonance Plasma Etching Of Gaas And Algaas, Paul G. Snyder, Natale J. Ianno, B. Wigert, S. Pittal, B. Johs, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

In situ real time spectroscopic ellipsometry measurements were made during electron cyclotron resonance plasma etching of radio frequency biased GaAs and AlGaAs samples. Gas mixtures used were CH₄/H₂/Ar, pure H₂ , and pure Ar. Ellipsometry provided information about damage to the surface region and AlGaAs epilayer thickness. For the methane mixture GaAs etch, damage appeared in the form of redshifted and broadened E₁ and E₁+ Δ₁ critical point features in a surface layer several tens of nm thick. The damage layer began forming within a few seconds after the start of …

Safe Stratified Datalog With Integer Order Programs, Peter Revesz

School of Computing: Conference and Workshop Papers

Guaranteeing termination of programs on all valid inputs is important for database applications. Termination cannot be guaranteed in Stratified Datalog with integer (gap)-order programs on generalized databases because they express any Turing-computable function. This paper introduces a restriction of those programs that can express only computable queries. The restricted language has a high expressive power and a non-elementary data complexity.

Determination Of Alas Optical Constants By Variable Angle Spectroscopic Ellipsometry And A Multisample Analysis, C. M. Herzinger, H. Yao, Paul G. Snyder, F. G. Celii, Y. C. Kao, B. Johs, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

Using variable angle spectroscopic ellipsometry, optical constants for AlAs (1.4-5.0 eV) are presented which are simultaneously compatible with measured data from four different samples. The below-gap index values are compatible with published prism measured values. The second derivative spectrum are compatible with published values above the direct band gap. The AlAs spectra is Kramers-Kronig self-consistent over the measured range and is compatible with published values from 0.6 to 1.4 eV. The optical constants for thin (<50 >Å) GaAs caps on AlAs are shown to be different from bulk GaAs values and require special consideration when fitting ellipsometric data. For the …

Optical Constants Of GaXIn1-XP Lattice Matched To Gaas, Mathias Schubert, V. Gottschalch, Craig M. Herzinger, Huade Yao, Paul G. Snyder, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

The optical constants of Ga_0.51In_0.49P have been determined from 0.8 to 5.0 eV using variable-angle spectroscopic ellipsometry measurements at room temperature. The metal-organic vapor-phase-epitaxy-grown samples were x-ray analyzed to confirm lattice matching to the GaAs substrate. The effects of the native oxide were numerically removed from the data to determine the intrinsic optical constants. This is important because the optical constants reported become generally useful for modeling multiple-layer structures. A Kramers-Kronig analysis was used to reduce interference-related fluctuations in the below-gap refractive index. Near the band edge a mathematical form for excitonic absorption was included. Critical …

Novel Kalman Filtering Method For The Suppression Of Gyroscope Noise Effects In Pointing And Tracking Systems, Marcelo C. Aigrain

Department of Electrical and Computer Engineering: Faculty Publications

A primary cause of degraded performance in pointing and tracking systems is the jitter in the line of sight. This jitter is caused by the residual angular motion of the stabilized platform within the system. A major contributor to this residual motion is the gyroscope noise. Thus, to reduce angular jitter, lower-noise gyroscopes are selected, generally at a premium cost. Another approach is to enhance the accuracy of the gyroscopes electronically (by suppressing measurement noise) before their outputs are fed into the stabilized platform control system. Optimal filtering techniques can be used for this purpose. The goal is to estimate …

Apparatus For 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 supply 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.

Inp Optical Constants Between 0.75 And 5.0 Ev Determined By Variable-Angle Spectroscopic Ellipsometry, C. M. Herzinger, Paul G. Snyder, B. Johs, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

Using variable-angle spectroscopic ellipsometry (VASE) InP optical constants for photon energies have been determined in the range from 0.75 to 5.0 eV, which includes the fundamental gap at 1.35 eV. Above 1.5 eV the results are consistent with previously measured pseudovalues from an oxide-stripped sample when a very thin residual over-layer is accounted for. They are also shown to be compatible with previously published prism measurements of refractive index below the band gap. Real and imaginary parts of the dielectric function are shown to be Kramers-Kronig (KK) self-consistent above the gap, and the KK analysis was used to extend the …

Losslees Compression Of Rgb Color Images, Nasir D. Memon, Khalid Sayood

Department of Electrical and Computer Engineering: Faculty Publications

Although much work has been done toward developing lossless algorithms for compressing image data, most techniques reported have been for two-tone or gray-scale images. It is generally accepted that a color image can be easily encoded by using a gray-scale compression technique on each of the three accounts the substantial correlations that are present between color planes. Although several lossy compression schemes that exploit such correlations have been reported in the literature, we are not aware of any such techniques for lossless compression. Because of the difference in goals, the best way of exploiting redundancies for lossy and lossless compression …

Campus Telecommunications Systems: Managing Change, Association Of College And University Telecommunications Administrators

ACUTA: Other Publications

The purpose of this book is to provide a broadbased understanding of the rapidly changing environment of campus telecommunications. The anticipated audience for this material is the non-technical university administrator who may not have direct responsibility for telecommunications, but has a need to understand the general environment in which his telecommunications manager functions and the basic concepts of the technology. Five topic areas were selected that best cover the preponderance of issues. No attempt has been made to associate or closely coordinate materials from one chapter's subject to that of any other. Each chapter generally stands alone. In total, however, …

Enhanced 911 Service In A Private Branch Exchange Using Uswest Ps/Ali Service

ACUTA: Other Publications

In This Issue

Author

Introduction

EP11 Operation Overview

US West Communications E911 Private Switch/Automatic Location

Identification Feature

Implementation of E911 with PS/ALI At Colorado State University

Overview

Planning ALI Database Input

SL- 100 PBX Database and Trunking

Pre-Testing

Other Issues and Difficulties

Cost

Conclusion

Addendum A

Addendum B

United States Patent: Ellipsometer, John A. Woollam, Blaine D. Johs, David W. Doerr, Reed A. Christenson

Department of Electrical and Computer Engineering: Faculty Publications

To sense characteristics of a sample, an ellipsometer includes a pivotal diffraction grating positioned to receive white light from the analyzer without further focusing of the light after the light leaves the sample. The diffraction grating is focused on the sensor at a predetermined angle with a precision of at least plus or minus one-half degree using an alignment-sensing means positioned between the analyzer and diffraction grating. The sensor includes an aperture through which the incident beam of light is transmitted, light-sensitive areas on opposite sides of said sensor and a comparator for comparing the signal from said light-sensitive areas. …

Complex Index-Of-Refraction Measurements For Rp-1 Liquid Rocket Fuel, Dennis R. Alexander, Ramu Kaiwala, Robert D. Kubik, Scott A. Schaub

Department of Electrical and Computer Engineering: Faculty Publications

Complex index-of-refraction values of RP-1 liquid rocket fuel are reported at laser wavelengths of 0.193 m (ArF excimer), 0.4765 m (argon ion), 0.488 im (argon ion), 0.5145 ji.m (argon ion), 0.532 m (Nd-YAG, frequency doubled), 0.6328 pm (He-Ne), 1 .064 im (Nd-YAG), and 10.5915 im (C02). The imaginary part of the index of refraction (k) is determined by traditional transmission methods. The real part (flr) at the specific laser lines is determined using reflectance measurements, critical-angle measurements, Mueller matrix elements, and Michelson interferometric measurements. Reflectance measurements are used to obtam n at a wavelength of 0.193 m. The critical-angle method …

Constraint Objects, Divesh Srivastava, Raghu Ramakrishnan, Peter Revesz

School of Computing: Conference and Workshop Papers

We describe the Constraint Object Data Model (CODM), which enhances an object-based data model with existential constraints to naturally represent partially specified information. We present the Constraint Object Query Language (COQL), a declarative, rule-based query language that can be used to infer relationships about and monotonically refine information represented in the CODM. COQL has a model-theoretic and an equivalent fixed-point semantics, based on the notions of constraint entailment and "proofs in all possible worlds." We also provide a novel polynomial-time algorithm for quantifier elimination for set-order constraints, a restricted class of set constraints that uses membership of subset-equal.

Interferometric Determination Of The Quadratic Electro-Optic Coefficient Of Nitrobenzene, Harshad P. Sardesai, William C. Nunnally, P. F. Williams

P. F. (Paul Frazer) Williams Publications

An interferometric method that was used to measure the electro-optic s₁₁ coefficient of nitrobenzene is presented. The method uses a Mach-Zehnder interferometer arrangement that produces a finite fringe interferogram. A nitrobenzene Kerr cell is placed in one arm of the interferometer and a pulsed high voltage is applied to the two rectangular electrodes. The voltage application causes the fringe image to shift in time, and this fringe shift is measured by a streak camera that streaks the fringe image across a slit. The streak start time is chosen before the application of the voltage pulse and ends after the …

Field Measurements Of Natural And Artificial Targets Using A Mid-Infrared Laser Reflectance Sensor, Ram M. Narayanan, Steven E. Green

Department of Electrical and Computer Engineering: Faculty Publications

tunable mid-infrared CO₂ laser reflectance sensor operating in the 9-11 pm wavelength range has been developed and field-tested at the University of Nebraska. This system is capable of gathering reflectance data at various wavelengths, incidence angles and linear polarization combinations. Preliminary measurements of various natural and artificial targets such as soil, coniferous and deciduous trees, concrete and brick building material at distances of up to 100 m demonstrate the potential of this system to characterize the mid-infrared reflectance of terrain features for remote sensing applications. Field-acquired data compare well with data on similar materials measured in the laboratory under …

Simple High-Quality Lossy Image Coding Scheme, Shaolin Bi, Khalid Sayood

Department of Electrical and Computer Engineering: Faculty Publications

A simple yet efficient image data compression method is presented. This method is based on coding only those segments of the image that are perceptually significant to the reconstruction of the image. Sequences of image pixels whose gray-level differences from the pixels of the previous row exceed two prespecified thresholds are considered significant. These pixels are coded using a differential pulse code modulation scheme that uses a 15-level recursively indexed nonuniform quantizer for the first pixel in a segment and a 7-level recursively indexed nonuniform quantizer for all other pixels in the segment. The quantizer outputs are Huffman coded. Simulation …

Gyroless Line-Of-Sight Stabilization For Pointing And Tracking Systems, Marcelo C. Aigrain

Department of Electrical and Computer Engineering: Faculty Publications

A new platform stabilization approach is described where miature, low-cost, linear accelerometers are used (instead of gyroscopes) for line-of-sight (LOS) stabilization. This is accomplished by placing the accelerometers at strategic locations and combining their outputs so that angular motion is determined from linear acceleration measurements. The control system uses the sensed angular accelerations to generate movement commands for the gimbal servomotors in the stabilization platform. This counterrotates the imaging device to stabilize its LOS. The use of accelerometers allows the servo system to operate in an acceleration control mode, which is more desirable than position or velocity control modes, typical …

Photoellipsometry Determination Of Surface Fermi Level In Gaas (100), Yi-Ming Xiong, Paul G. Snyder, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

Photoellipsometry, a new contactless optical method, is presented, Related to photoreflectance, this method utilizes spectroscopic ellipsometry with the addition of a laser pump beam directed at nearly normal incidence onto the sample surface, where photoexcited electron-hole pairs modify the built-in electric field as a result of the photovoltaic effect. The field-induced changes in the real and imaginary parts of the complex pseudodielectric function can be directly measured, and analyzed in terns of the pump beam power density or the probe beam photon energy to determine parameters, such as surface Fermi level, built-in field strength, depletion depth, broadening, critical point energies, …

Spectroscopic Ellipsometry Studies Of Hf Treated Si (100) Surfaces, Huade Yao, John A. Woollam, Samual A. Alterovitz

Department of Electrical and Computer Engineering: Faculty Publications

Both ex situ and in situ spectroscopic ellipsometry (SE) measurements have been employed to investigate the effects of HF cleaning on Si surfaces. The hydrogeniterminated (H-terminated) Si surface was modeled as an equivalent dielectric layer, and monitored in real time by SE measurements. The SE analyses indicate that after a 20-s 9:l HF dip without rinse, the Si ( 100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si (100) surface was observed, in an ultrahigh vacuum (UHV) chamber, and analyzed by the in situ SE. Evidence for desorption of the H-terminated …

Inhibition Of Surface-Related Electrical Breakdown Of Long P+-I-N+ Silicon Structures, F. E. Peterkin, P. F. Williams, B. J. Hankla, L. L. Buresh, S. A. Woodward

P. F. (Paul Frazer) Williams Publications

Semiconductors such as silicon and GaAs appear attractive for use in high voltage devices because of their high bulk dielectric strength. Typically, however, such devices fail at a voltage well below that expected due to a poorly understood, surface-related breakdown process. In this letter we present empirical results which show that such breakdown of long silicon p⁺-i-n⁺ devices can be inhibited by the application of weak visible or near-infrared illumination. These results suggest a technique for avoiding surface flashover in practical high voltage devices, and provide information about the physical mechanisms responsible for initiating …

Introduction To Electrical Engineering And The Art Of Problem Solving: Volume I, P. Frazer Williams

P. F. (Paul Frazer) Williams Publications

These notes were written to accompany a two-semester introductory course in Electrical Engineering. The primary goal of the course is to introduce you to the art of technical problem solving. Conventional Electrical Engineering curricula, in favorable cases at least, produce engineers who are reasonably adept at operating many of the tools important to the field, such as mathematics and circuit analysis. Often, however, these engineers lack skill in choosing which tools to use and in designing a plan of attack to solve problems which are new to them, even though they have all the information and skills needed to fabricate …

Introduction To Electrical Engineering And The Art Of Problem Solving: Volume Ii, P. Frazer Williams

P. F. (Paul Frazer) Williams Publications

These notes were written to accompany a two-semester introductory course in Electrical Engineering. The primary goal of the course is to introduce you to the art of technical problem solving. Conventional Electrical Engineering curricula, in favorable cases at least, produce engineers who are reasonably adept at operating many of the tools important to the field, such as mathematics and circuit analysis. Often, however, these engineers lack skill in choosing which tools to use and in designing a plan of attack to solve problems which are new to them, even though they have all the information and skills needed to fabricate …