| Investigation of Normal Incidence High Performance P-Type Strained Layer InGaAs/AlGaAs and GaAs/AlGaAs Quantum Well Infrared Photodetectors |
30 JUN 97 |
97 pages |
| Authors:
Jerome T. Chu; Sheng S. Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
 | In this research project, we have demonstrated several novel strained layer p-type quantum well infrared photodetectors (QWIPs) for the 3-5 um mid- wavelength infrared (MWIR) and 8-14 um long-wavelength infrared (LWIR) detection. These normal incidence p-QWIPs employed the tensile and compressive strained layer quantum well structures to enhance the performance of the p-QWIPs in the MWIR and LWIR spectral bands. Peak detection wavelengths at 7.4, 8.4, 9.2 and 10.1 um ... |
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| Investigation of Normal Incidence High-Performance P-type Strained Layer InGaAs/AlGaAs and GaAs/AlGaAs Quantum Well Infrared Photodetectors |
15 FEB 96 |
41 pages |
| Authors:
Jerome T. Chu; Sheng S. Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| The objective of this project is to perform theoretical and experimental studies of dark current, photocurrent, optical absorption, spectral responsivity, noise, and detectivity for the normal incidence strained layer p- type III-V semiconductor quantum well infrared photodetectors (QWIPs) developed under this program. The material systems under investigation include InGaAs/ InAlAs on InP substrates and GaAs/InGaAs or AlGaAs/InGaAs on GaAs substrates. The project will study the usage and effects of biaxial ... |
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| Investigation of Normal Incident High Performance P-type Strained Layer InGaAs/AlGaAs and GaAs/AlGaAs Quantum Well Infrared Photodetectors |
31 JUL 95 |
45 pages |
| Authors:
Jerome T. Chu; Sheng S. Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| We have made excellent progress towards the program goals. A significant achievement was made in the development of a new compressively strained p-type InGaAs/AlGaAs QWIP grown on GaAs by MBE with very low dark current densities. This new QWIP achieved two color detection with detection peaks at 7.4 micrometers in the LWIR band and 5.5 micrometers in the MWIR band. This detector is under background limited performance (BLIP) at temperatures ... |
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| Investigation of a Normal Incident High Performance P-type Strained Layer In(0.3)Ga(0.7)As/In(0.52)Al(0.48)As Quantum Well Infrared Photodetector |
15 FEB 95 |
44 pages |
| Authors:
Jerome T. Chu; Sheng S. Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| During this reporting period, we have made excellent progress towards the program goals. A significant achievement was made in the development of a new compressionally strained p-type GaAs/InGaAs QWIP grown on GaAs by MBE. This new QWIP achieved two color detection with detective peaks at 8.9 um an 8.4 micrometers in the LWIR band and 5.5 micrometers in the MWIR band. This detector is under background limited performance (BLIP) at ... |
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| Development of Ultra-Low Dark Current, High Performance III-V Quantum Well Infrared Photodetectors (QWIPs) for Focal Plane Arrays Staring Imaging Sensor Systems |
01 FEB 95 |
209 pages |
| Authors:
Sheng S. Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| This final report presents the research findings and accomplishments made on the research project sponsored by ARPA/ONR under grant No. N00014-91-J- 1976 for the period of 08/01/91 to 02/01/95. Specific achievements include: (1) development of the first bound-to-miniband (BTM) transition GaAs/GaA1As QWIP for 8-12 micrometers detection; large area (128/128, 256x256, and 512x512) FPAs based on the BTM QWIP structure have been demonstrated by Martin Marietta with excellent imagery, (2) development ... |
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| The Gauss Machine |
01 NOV 94 |
332 pages |
| Authors:
Fred J. Taylor; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| The Gauss machine is a SlMD systolic array architecture which takes advantage of the Galois-enhanced quadratic residue number system (GEORNS) to form reduced complexity arithmetic elements. The Gauss machine is targeted at front-end signal and image processing applications. With a 2 x 2 array of GEQRNS multiplier-accumulators operating at 10 MHz the Gauss machine can achieve a peak equivalent throughput of 32O million operations per second when performing complex arithmetic. ... |
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| Investigation of a Normal Incidence High-Performance P-Type Strained Layer In(0.3)Ga(0.7)As/In(0.52)Al(0.48)As Quantum Well Infrared Photodetector |
15 JUL 94 |
34 pages |
| Authors:
Max N. Yoder; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| During this reporting period, we have made excellent progress towards the program goals. A significant achievement was made in the development of a new compressionally strained p-type GaAs/InGaAs QWIP grown on GaAs by MBE. This new QWIP achieved two color detection with detective peaks at 8.9 microns and 8. 4 microns in the LWIR band and 5.5 microns in the MWIR band. This detector is under background limited performance (BLIP) ... |
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| Development of Ultra-Low Noise, High Performance III-V Quantum Well Infrared Photodetectors (QWIPs) for Focal Plane Array Staring Image Sensor Systems |
01 MAY 94 |
41 pages |
| Authors:
Sheng S. Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| During this reporting period (02-01-94 to 04-30-94) we have continued to make excellent progress. We report two new normal incidence p-type strained- layer III-V quantun well infrared photodetectors (QWIPs) for 3-5 and 8-14 um detection. An ultra-low dark current p-type tensile strained-layer (PTSL) In(0. 3)Ga(0.7)As/In(0.52)Al(0.48)As QWIP grown on InP by MBE for 8-14 um detection has been developed. It shows BLIP for T<100 K. Due to a 1.5% lattice mismatch ... |
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| Investigation of a Normal Incidence High-Performance P-Type Strained Layer In0.3Ga0.7As/In0.52Al0.48As Quantum Well Infrared Photodetector |
15 JAN 94 |
25 pages |
| Authors:
Jerome T. Chu; Sheng S. Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| During this reporting period, we have made significant strides towards the program goals. A major breakthrough was made in the development of a new strained layer p-type InGaAs/InAlAs QWIP grown on InP by MBE. This new QWIP achieved an ultra-low dark current and a very high detectivity at 8.1 micrometers and 77 K. This detector is under background limited performance (BLIP) at temperatures up to 100 K, which is the ... |
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| Development of Ultra-Low Noise, High Performance III-V Quantum Well Infrared Photodetectors (QWIPs) for Focal Plane Array Staring Image Sensor Systems |
01 NOV 93 |
43 pages |
| Authors:
Sheng S. Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| During this reporting period (08-01-93 to 10-31-93) we have continued to make significant progress towards the program goals. We have made a major breakthrough in the development of a new normal incidence p-type strained-layer InGaAs/InAlAs QWIP grown on InP by MBE, which achieved an ultra-low dark current and very high detectivity at 8.1 urn and 77 K. The detector is under background limited performance (BLIP) for T<100 K, which is ... |
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| Development of Ultra-Low Noise, High Performance III-V Quantum Well Infrared Photodetectors (QWIPs) for Focal Plane Array Staring Image Sensor Systems |
01 AUG 93 |
64 pages |
| Authors:
Sheng S. Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| During this reporting period we have continued to make excellent progress towards the program goals. We have made a major breakthrough in the development of a new normal incidence p-type strained layer InGaAs/InAlAs QWIP grown on InP by MBE, which achieved both the lowest dark current and highest detectivity ever reported for a QWIP operating at 8.1 um and 77 K. The device dark current at 77 K is one ... |
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| Development of Ultra-Low Noise, High Sensitivity Planar Metal Grating Coupled III-V Multiquantum Well Infrared Detectors for Focal Plane Array Staring IR Sensor Systems |
01 MAY 93 |
71 pages |
| Authors:
Sheng S. Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| To develop ultra-low dark current and high detectivity planar metal grating coupled bound-to-miniband (BTM) III-V quantum well infrared photodetectors (QWIPs) for 8 to 12 um focal plane arrays (FPAs) staring IR sensor systems. To develop novel type-I and type II III-V QWIPs with multicolor, broad and narrow band spectral response in the 8 to 14um wavelength range. The material systems to be studied include GaAS/AlGaAs, AlAs/AlGaAs, InGaP/GaAs (by MOCVD) grown ... |
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| Development of Ultra-Low Noise, High Sensitivity Planar Metal Grating Coupled III-V Multiquantum Well Infrared Detectors for Focal Plane Array Staring IR Sensor Systems |
01 MAY 93 |
72 pages |
| Authors:
Shang S. Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| During this reporting period we have continued to make progress towards the program goals. We have designed, fabricated, and characterized several new types of 2-D metal grating coupled n-type GaAs/AlGaAs, AlAS/AlGaAs, InAlAs/InGaAs, and InGaP/GaAs QWIPs for 2-14 micrometers focal plane arrays (FPAs) staring infrared sensor applications. In addition, a new normal incidence two-color p-type strained layer InGaAs/InA1As QWIP has been developed for the first time with highest detectivity and low ... |
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| Location and Characterization of In-Cloud Lightning Currents by Multiple Station VHF and Electric Fields Measurements |
14 DEC 92 |
6 pages |
| Authors:
Ewen M. Thomson; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| The network established in 1991 to measure electric fields in a 600 Hz to 3.5 MHz 3dB bandwidth at five stations at Kennedy Space Center was enhanced in 1992. New microprocessor-controlled remote controls were developed, additional remote calibration signals were added, and new sensor amplifiers were implemented so that we could record the derivative of the electric field, dE/dt. These improvements enabled us to increase our bandwidth from 3.5 MHz ... |
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| Development of Ultra-Low Noise, High Sensitivity Planar Metal Grating Coupled AlGaAs/GaAs Multiquantum Well IR Detectors for Focal Plane Array Staring IR Sensor Systems |
10 NOV 92 |
57 pages |
| Authors:
Sheng S. Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| Project Objectives: to develop ultra-low dark current and high detectivity planar metal grating coupled bound-to-miniband(BTM) III-V quantum well infrared photodetectors, (QWIPs) for 8 to 12 microns focal plane array (FPA) staring IR sensor system; to develop novel type-I and type-II III-V QWIPs with multicolor, broad and narrow band spectral response in the 8 to 14 microns wavelength range. The material systems to be studied include GaAs/AlGaAs, AlAs/ AlGaAs, and InGaP/GaAs ... |
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| Development of Ultra-Low Noise, High Sensitivity Planar Metal Grating Coupled AlGaAs/GaAs Multiquantum Well IR Detectors for Focal Plane Array Staring IR Sensor Systems |
07 AUG 92 |
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| Authors:
Sheng S. Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
 | Project objectives include the following: (1) To develop low dark current and high detectivity planar metal grating coupled bound-to-miniband III- V multiquantum well infrared photodetectors (QWIPs) for 8 to 12 microns FPA and IR sensor applications. (2) To develop other new types of III-V multicolor QWIPs with broad and multicolor infrared spectral response (5 to 18 microns). (3) To conduct theoretical and experimental studies of the planar metal grating-coupled structures ... |
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| Tailoring of Electron and Hole Energies in Strained GaAsP/AlGaAs Quantum Wells using Fluorine Impurity Induced Layer Disordering, |
JUL 1992 |
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| Authors:
Utpal Das; Steve Davis; Jia-T. Hsu; Ramu V. Ramaswamy; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
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| Electroabsorption in GaAs/AlGaAs quantum well (QW) waveguides is known to be strongly polarization dependent. Electro-optic effects for the polarization perpendicular to the layer (which shows a strong light-hole (LH) exciton peak) is negligible for the (100) grown QWs. For polarization parallel to the layers the oscillator strengths of the excitons are smaller due to the presence of both the LH and the heavy-hole (HH) exciton transitions. This necessitates a modification ... |
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| Directional Coupler with Varying Placement of Nonlinearity in Quaternary Semiconductors, |
22 MAY 1992 |
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| Authors:
C. P. Hussell; R. Srivastava; R. V. Ramaswamy; M. Bloemer; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| The large optical nonlinearities exhibited by III-V multiple quantum well (MQW) materials have afforded some optimism in achieving large all-optical switching ratios with low threshold power and short device length. By using multiple quantum wells in the coupling as well as the guiding regions, Kam Wa was the first to demonstrate partial switching between two parallel GaAs/AlGaAs MQW channel waveguides. This device, however, exhibited very high loss. Cada argued that ... |
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| Development of Ultra-Low Noise, High Sensitivity Planar Metal Grating Coupled AlGaAs/GaAs Multiquantum Well IR Detectors for Focal Plane Array Staring IR Sensor Systems |
01 MAY 92 |
27 pages |
| Authors:
Sheng S. Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| In this reporting period, we have continued to make a significant progress towards the program goals. We have designed, fabricated and characterized several metal grating coupled bound-to-miniband (BTM) and step- bound-to-miniband (SBTM) transition QWIPs on the GaAs ad InP substrates for 8-12 microns focal plane arrays staring infrared sensor applications. Specific tasks performed include: (1) the design and growth of several (BTM) GaAs- and (SBTM) in GaAs-based QWIP structures as ... |
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| Characterization of Photorefractive Effect in Annealed Proton-Exchanged (APE) LiNbO3 Waveguides in the Visible Region, |
APR 1992 |
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| Authors:
Xianofan Cao; Takumi Fujiwara; Ramu V. Ramaswamy; Ramakant Srivastava; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
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| Annealed proton exchanged(APE) LiNbO3 waveguides with recovered electro-optic/nonlinear coefficients and low propagation loss are widely used in integrated optics. Although it is known that the PE LiNbO3 waveguides have higher resistance to photorefractive damage than Ti-diffused LiNbO3 waveguides), a feature which is quite attractive for nonlinear guided wave applications such as efficient diode laser doubling), a quantitative characterization of photorefractive effect in APE LiNbO3 waveguides in the visible region has ... |
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| Development of Ultra-Low Noise, High Sensitivity Planar Metal Grating Coupled AlGaAs/GaAs Multiquantum Well IR Detectors for Focal Plane Array Staring IR Sensor Systems |
01 FEB 92 |
31 pages |
| Authors:
Max N. Yoder; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| During this reporting period (11-01-91 to 1-31-92), we have continued the study of the performance characteristics of the metal grating coupled bound- to-miniband (BTM) and step-bound-to-miniband (SBTM) transition multiquantum well(MQW)/superlattice (SL) barrier infrared (IR) detectors formed on the GaAs and InP substrates for 8-12 micrometer focal plane arrays and image sensor applications. Specific tasks performed included: (1) designed and grown several (BTM) GaAs- and (SBTM) InGaAs-based QWIP (quantum well infrared ... |
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| Location and Characterization of In-Cloud Lightning Currents by Multiple Station VHF and Electric Field Measurements |
14 DEC 91 |
6 pages |
| Authors:
Ewen M. Thomson; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| A network has been established that measures and records electric fields in a 600 Hz to 3.5 MHz 3dB bandwidth at five stations at Kennedy Space Center. Signals were recorded at the central station with a 20 MS/s digitizing system that operating on a 24 hour per day basis. Data has been obtained from both lightning and small discharges that do not fit the commonly accepted definition of lightning . ... |
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| Development of Ultra-Low Noise, High Sensitivity Planar Metal Grating Coupled AlGaAs/GaAs Multiquantum Well Detectors for Focal Plane Array (FPA) staring IR Sensor Systems |
01 NOV 91 |
21 pages |
| Authors:
Shen S. Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| Since the beginning of this DARPA sponsored IR detector project, we have made significant progress toward achieving the original project goals. We have designed and fabricated two new types of IR detectors using step- bound-to- miniband (SBTM) and bound-to-miniband (BTM) transition multiple-quantum-well (MQW)/superlattice (SL) barrier structures grown by MBE technique. The results showed that the dark current for the SBTM IR detector measured at 77 K was more than one ... |
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| Comparison of the RF Frequency Spectra of HEMP and Lightning |
01 MAR 91 |
47 pages |
| Authors:
Martin A. Uman; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| Cloud pulses are much more common than these earlier studies indicate. Our spectra of the largest overhead cloud pulses are nearly parallel to but significantly below the HEMP spectrum from 1MHz to 50 MHz, while obtained from lighting tens of kilometer offshore over salt water show faster relative decay with increasing frequency, are significantly below ours between 10 and 50MHz, and are about equal to ours between 3 and 10 ... |
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| Ultra High Performance, Highly Reliable, Numeric Intensive Processors and Systems |
OCT 89 |
36 pages |
| Authors:
Fred J. Taylor; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| Arithmetic bandwidth remains one of the principal bottlenecks in real-time-high-end signal, image, and data processing applications. The problem is compounded when complex arithmetic is required. The problem, unfortunately, does not stop there. For military applications, size (volume) and power dissipation often are as important as bandwidth. Unfortunately speed and complexity (size-power) metrics are often in conflict. As a result, the defense signal processing systems designer finds that performance requirements often ... |
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| Army Science and Technology Fellowship |
OCT 89 |
5 pages |
| Authors:
Frederick J. Taylor; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| During a three year period the High-Speed Digital Architecture Laboratory (HSDAL) benefited enormously from the award of two ARO Fellowships. The Fellowships were awarded to support the main-line ARO activities of the HSDAL which has been, and continues to be, high-speed computer architecture and digital signal processing. The HSDAL has, we feel, an international reputation in several sub-areas of these broad technologies. Digital architecture. (jes) |
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| New Perspectives of Silicon Carbide: An Overview, with Special Emphasis on Noise and Space-Charge-Limited Flow |
88 |
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| Authors:
C. M. Van Vliet; G. Bosman; L. L. Hench; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
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| In this paper we review some of the novel work performed at the University of Florida. We found that the polytypism of this material leads to very clearly discernible space-change-limited (SCL) flow. A study of this phenomenon, together with studies on generation-recombination noise, indicated that a detailed analysis of trap and impurity levels in this material is possible (9-11). Space-charge-limited diodes, with quadratic or exponential characteristics, are easily obtainable. Besides, ... |
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| Ion-Exchanged Waveguides for Signal Processing Applications - A Novel Electrolytic Process |
07 MAR 87 |
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| Authors:
R. V. Ramaswamy; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
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| Ion exchange process and technology for fabrication of optical waveguides has been studied systematically to improve the reproducibility and establish the correlation between the process parameters and the component characteristics. Two-step process has been studied extensively and used for fabrication of low-loss fiber-compatible single-mode buried channel waveguides using the Na+ - Ag+ cation pair. Nonlinear waveguides have been studied theoretically and some of the predictions have been verified experimentally in ... |
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| DLTS Analysis and Modeling of Electron and Proton Irradiated (AlGa)As/ GaAs Multijunction Solar Cells |
MAR 87 |
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| Authors:
Sheng S. Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
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| A numerical model has been developed to calculate the displacement defects, the damage constant of minority carrier diffusion length and the degradation of short circuit current (I sub sc), open circuit voltage (V sub oc) and conversion efficiency (eta sub c) in the 1 MeV electron and proton irradiated AlGaAs/GaAs/InGaAs multijunction junction solar cell under normal incidence conditions. The results show good agreement between our calculated values and the experimental ... |
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| Control of Linear Systems Over Commutative Normed Algebras with Applications |
FEB 87 |
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| Authors:
Edward W. Kamen; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
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| The research centered on the development of a control theory for various classes of complex linear systems, including systems with time delays, systems with unknown parameters and time-varying systems. In the work on systems with time delays, we have been able to prove that stabilizable systems with one or more noncommensurate time delays can always be stabilized using a lumped (finite-dimensional) compensator. In many cases of interest such as delays ... |
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| Study of Grown-in Defects and Transport Properties versus Growth Parameters in III-V Epitaxial Films |
05 JAN 87 |
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| Authors:
Sheng S. Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
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| Investigation on the nature of deep-level defects in Gallium Arsenide and Aluminum sub x Gallium sub 1-x Arsenide (e.g., EL2 and DX center) grown under the various conditions has been performed by; 1) modeling the physical origins of EL2 center in GaAs based on the kinetic reaction equations and the analysis of field-enhanced emission rate, 2) correlation of deep-level defects in multi-epilayer GaAs grown by metalorganic chemical vapor deposition to ... |
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| Modeling and DLTS Analysis of Irradiated III-V Multijunction Solar Cells |
FEB 86 |
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| Authors:
Sheng S. Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| The objective of this research project was to develop a simple theoretical model based on Wilson's model to calculate the displacement damages introduced by either protron or electron irradiation in AlGaAs, GaAs, InGaAs and Ge. These calculations would then be applied to obtain an optimized triple junction solar cell structure using these materials with a specified end of life conversion efficiency. Empirical formulae and theoretical expressions were derived for calculating ... |
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| Observation of Single-Carrier Space-Charge-Limited Flow in Nitrogen- Doped Alpha-Silicon Carbide |
15 AUG 85 |
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| Authors:
S. Tehrani; J. S. Kim; L. L. Hench; C. M. Van Vliet; G. Bosman; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| This paper first reviews the properties of silicon carbide, in which polytypism is a salient feature. If a highly compensated insulating polytype is sandwiched between low resistive polytypes, space-charge injection will occur. The theory of space-charge-limited current flow in the presence of traps is reviewed and a somewhat different version of the standard theory is presented, which shows more clearly the ohmic and space-charge-limiting regimes. Close analytical parametric forms for ... |
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| Study of Grown-In Defects Verses Growth Parameters in GaAs and Al(x) Ga(1-x)AS Epitaxial Films Grown by LPE and MOCVD Techniques |
15 JUN 85 |
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| Authors:
Sheng S. Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
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| A model for describing the physical origins of the EL2 center in the GaAs is presented based on the kinetic reaction equations and the analysis of electric-field enhanced emission rates for the four different types of potential well. It has been shown that the EL2 center may be ascribed to two different types of native defect: One level (E sub c-0.83 eV) attributing to the antisite defect, As sub Ga ... |
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| Stabilization of Time-Delay Systems Using Finite-Dimensional Compensators |
JAN 85 |
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| Authors:
E. W. Kamen; P. P. Khargonekar; A. Tannenbaum; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| For linear time-invariant systems with one or more noncommensurate time delays, necessary and sufficient conditions are given for the existence of a finite-dimensional stabilizing compensator. In particular, it is shown that a stabilizable time-delay system can always be stabilized using a finite- dimensional compensator. The problem of explicitly constructing finite- dimensional stabilizing compensators is also considered. Originator supplied keywords include: Systems with time delays; Control theory; and Stabilization by feedback. ... |
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| Observation of Single-Carrier Space Charge-Limited Flow in Nitrogen- Doped Alpha-Silicon Carbide. II. Electrical Noise |
85 |
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| Authors:
S. Tehrani; L. L. Hench; C. M. Van Vliet; G. Bosman; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| Noise spectra of alpha-SiC in the presence of space-charge-limited flow are attributed to trapping noise. In the ohmic regime, S sub delta I approximate value of I sq. and in the ohmic and low-voltage quadratic regime S sub delta I approximate value of I times absolute value of V as required by the theory. The trapping levels are determined from the slope of the time constants versus 1/T; the results ... |
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| Study of 1/f Noise in Solids |
31 OCT 84 |
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| Authors:
C. M. Van Vliet; G. Bosman; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| In the introduction an overview is given of the status of 1/f noise at the end of the contract period. We indicate that the 1/f noise observed in our laboratory, as well as in other places, quite often yields Hooge parameters of order 10-5 to 10-8, i.e., two to five orders less than a decade ago. Much of this noise can be seen as quantum 1/f noise which is the ... |
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| Studies of Grown-In Defects Versus Growth Parameters in III-V Compound Semiconductors |
JUN 1984 |
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| Authors:
S. S. Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| The objectives of this research are to conduct: (1) A detailed analysis of the grown-in defects and radiation induced defects in GaAs and other III-V materials grown by the LEC, VPE, LPE, and MOCVD techniques under different growth and annealing conditions, (2) Theoretical modelling of the native defects for identifying the physical origins of the deep-level traps in GaAs and other III-V materials, (3) Theoretical and experimental study of the ... |
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| Bistatic Radar Cross Sections of Chaff. |
MAR 1984 |
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| Authors:
P. Z. Peebles; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| Bistatic cross sections applicable to scattering from a cloud of randomly positioned and randomly oriented resonant dipoles, or chaff, are found. The chaff cloud can have an arbitrary location relative to an illuminating radar and the radar antenna can have an arbitrarily specified polarization. The receiver can be located arbitrarily in relation to the radar and chaff cloud and can also have arbitrary polarization (different from the transmitter antenna). Average ... |
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| Interaction between Subsystems of Vision and Motion Planning in Unmanned Vehicles with Autonomous Intelligence. |
1984 |
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| Authors:
A. Meystel; L. Holeva; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
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| A structure of preprocessing is described corresponding to a planner strata of the perception-cognition interaction within the machine intelligence for an autonomous mobile vehicle. A terraine is represented via a polygonal map. Algorithms are described which transform such a map into a database which can be used by PLANNER to solve motion planning problem. (Author. Copyright 1984 Society of Photo-Optical Instrumentation Engineers.) |
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| Computation Simulation of Autonomous Vehicle Navigation. |
1984 |
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| Authors:
A. Meystel; E. Koch; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
|
| A concept of navigation is simulated based upon heuristic search. A mobile robot with a vision system navigates with an unknown or an unclear map. The range of vision is limited, thus inflicting various judgements concerned with the comparison of alternatives of motion. The frequency of the decision-making procedure is limited by a definite time of computation. The system is simulated with a number of maps, and the results of ... |
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| Theoretical-Experimental Analysis of the Effects of Grain Boundaries on the Electrical Properties of SOI (Silicon-on-Insulator) MOSFETS |
NOV 1983 |
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| Authors:
J. G. Fossum; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
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| This first annual report describes the development of a physical model for thin-film SOI (insulating substrates) MOSFET that will form the basis of a computer model for existing circuit simulation programs, e.g., SPICE. The model will thus enable computer simulation of SOI ICs, e.g., stacked CMOS, the prevalent basis for three-dimensional ICs. The model characterizes the (effective) field-effect mobility, the threshold voltage, and the source-drain leakage of a MOSFET fabricated ... |
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| Study of Deep-Level Defects and Transport Properties vs Growth Parameters and Annealing Conditions in III-V Compound Semiconductors |
10 JUN 1983 |
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| Authors:
Sheng S. Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
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| The objectives of this research program are: (1) To investigate the grown-in defects and the effects of thermal and laser annealing on the grown-in defects in LEC grown Zn-doped InP, (2) to study the transport properties in n- type InP, (3) to characterize the grown-in defects vs annealing temperature in the LEC grown GaAs, and compare the deep-level defects in the MOCVD grown GaAs on semi-insulating GaAs- and Ge- substrates, ... |
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| Effect of Nonlinear Architectures on Monopulse Radar Angle Tracking Accuracy |
17 JAN 1983 |
48 pages |
| Authors:
Peyton Z. Peebles Jr; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
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| Many monopulse angle tracking radar systems are made up using nonlinear components, such as limiters and logarithmic amplifiers. This report describes several areas of work that all relate to monopulse angle tracking radars having at least one limiter in the signal processor. In one area the detailed angle tracking accuracy was determined for a sum-and-difference amplitude monopulse system having a sum channel limiter prior to the angle error detector. The ... |
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| Study of 1/f Noise in Solids |
1983 |
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| Authors:
Carolyn M. Van Vliet; Gijs Bosman; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
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| Noise measurements were made on gold metal films. The noise above 150K is of the form 1/f to the 1.2 power; below 150K the noise goes as 1/f with a maximum near 80K, then a continued decrease. The noise in GaAs n+n-n+ mesas of submicron dimensions is very low. The Hooge parameter is of the order of 10 to the minus 7th power, indicating that collisions are nearly absent. Intervally ... |
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| Lightning Physics: A Three Year Program |
1983 |
58 pages |
| Authors:
M. A. Uman; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
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| The work was reported in five publications: Calculations of Lightning Return Stroke Electric and Magnetic Fields above Ground, Electric Fields Preceding Cloud-to-Ground Lightning Flashes, A Comparison of Lightning Electromagnetic Fields with the Nuclear Electromagnetic Pulse in the Frequency Range 10000 to 10000000 Hz, Transient Electric and Magnetic Fields Associated with Establishing a Finite Electrostatic Dipole, and Variation in Light Intensity with Height and Time from Subsequent Lightning Return Strokes. ... |
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| Algebraic Theory of Linear Time-Varying Systems and Linear Infinite- Dimensional Systems |
NOV 1982 |
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| Authors:
Edward W. Kamen; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
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| The research centered on two major classes of linear systems: Linear time-varying systems and linear infinite-dimensional systems. A brief description of the work which has been carried out on each class of systems is given. (Author) |
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| Studies of Growth-In Defects and Transport Properties Versus Growth Parameters in III-V Compound Semiconductors |
10 JUN 1982 |
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| Authors:
Sheng S. Li; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
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| The objectives of this research project are: (1) to investigate the grown-in deep level defects vs. growth parameters (e.g., growth temperature, growth rate, Ga/As ratio, and substrate orientations) in GaAs epilayers grown by liquid phase epitaxial (LPE) and vapor phase epitaxial (VPE) techniques, (2) to study the transport properties vs. growth parameters in the LPE and VPE grown GaAs, and (3) to study the effects of combined thermal and injection ... |
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| Study of 1/f Noise in Solids |
JUN 1982 |
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| Authors:
Carel M. Van Vliet; Eugene R. Chenette; Gijs Bosman; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
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| This progress report is divided into four main parts. In Part A we begin with some introductory remarks on 1/f noise and the impact of the contributions performed during the present grant period. Next we give a survey of 1/f noise theory as it stands today, together with the experimental evidence for the various models. In Part B the experimental work performed under the grant is described. This entails the ... |
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| Study of 1/f Noise in Solids |
MAY 1981 |
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| Authors:
Karel M. VAN Vliet; Eugene R. Chenette; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL ENGINEERING
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| A Hewlett-Packard digital fast Fourier transform spectral analyser was purchased and adapted for our purpose by writing several computer programs for the output display. Test jigs for devices under test and preamplifiers were built. Further, a real time dual channel correlation spectral analyzer was designed and partially built. Measurements involving temperature fluctuations and correlations in metal films and in integrated circuit transistors are described. The latter have been recently completed. ... |
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Reports by Corporate Author
