PRINCETON UNIV NJ DEPT OF ELECTRICAL ENGINEERING AND COMPUTER SCIENCE
Most widely held works by PRINCETON UNIV NJ DEPT OF ELECTRICAL ENGINEERING AND COMPUTER SCIENCE
Noise Characteristics of Superlattice Energy Filters and Multi-Color Infrared Detection Using Quantum Well Microstructure ( Book )
2 editions published in 1998 in English and held by 2 libraries worldwide
This report describes the result from a systematic study on a new device structure, the corrugated quantum well infrared photodetector (C-QWIP), which is designed to couple normal incident radiation into the quantum well structures. The C-QWIP structure is an array of QWIP wires with slant sidewalls, fabricated by etching V-grooves through the detector active region down to the bottom contact. It utilizes total internal reflection at the sidewalls of these QWIP wires to create favorable optical polarization for absorption. We have demonstrated that it has higher coupling efficiency in comparison with the standard 45 deg edge coupled device. Also, the coupling efficiency is independent of pixel size and wavelength. In addition, due to partial removal of the active material, the dark current of the detector is reduced significantly. The combination of photocurrent increase and dark current decrease results in a larger photocurrent to dark current ratio rI, and thus a higher D() and a smaller NEdeltaT in array applications.
Digital Signal Processing ( Book )
4 editions published between 1982 and 1992 in English and held by 1 library worldwide
Virtually all of the important research results obtained were reported in journal articles and conference papers. Brief summaries of the major contributions are given. The summaries relate to: Digital Filter Design; Theory of the DFT; New Algorithms; Communication Networks; VLSI Architectures for Signal Processing; Adaptive and Nearly Optimal Detectors; Robust Detection; Structure of Random Processes; Quantization; and Sequential Detection.
Princeton VLSI Project ( Book )
4 editions published between 1982 and 1984 in English and held by 1 library worldwide
There are three major aspects to our project. The first concerns the development of ALI2 which is a procedural language approach to the layout of VLSI circuits. The second is the continuing investigation of the census language. Finally, the third is in the area of testing of VLSI circuits.
Ultrafast Processes and Spectroscopy with Free Electron Lasers ( Book )
3 editions published between 1987 and 1989 in English and held by 1 library worldwide
The goal of this project is twofold: 1) to demonstrate that the SCA Free Electron Laser (FEL) is a useful tool for time-resolved spectroscopy; and 2) to use the FEL with other ultrashort pulse sources to uncover the electronic processes in disordered semiconductors. Potentially, the SCA FEL is a near-ideal source for ultrashort time-spectroscopy. It delivers widely tunable, psec pulses with high peak power and at high repetition rate. However, pulse-to-pulse variations in duration, wavelength and phase within one micropulse may be a limitation for high quality spectroscopy. In addition, pulses below one picosecond and tunability around the laser wavelength are desirable. Essential experiments will demonstrate how useful the SCA FEL is in ultrashort time resolved spectroscopy, including pulse compression and generation of white light continuum. The second goal is to uncover the electronic processes in disorder materials. Understanding these processes is the key to understanding the physics in materials such as amorphous semiconductors or liquid semiconductors. In turn, understanding the physics of these materials will lead to novel devices or improved device operation and will impact on our models for other materials. Picosecond and femtosecond time-resolved measurements are carried out on a Si:H and its alloys with Ge and C. The electronic properties of carriers in the vicinity of the mobility edge are emphasized.
Study of Electronic Transport and Breakdown in Thin Insulating Films ( Book )
3 editions published between 1977 and 1980 in English and held by 1 library worldwide
Recent progress is reported in an ongoing program of studies of high-field effects in thin insulating films on semiconducting substrated. The investigations include further studies of the high-field generation of interface states in the Si-SiO2 system, description of a method for measuring interface state densities at low temperatures, a preliminary report of Auger observations of interface states in the Si-SiO2 system, and the results of further studies of high-field effects in the metal-aluminum oxide-silicon system.
Electron Transport in Heterojunction Superlattices ( Book )
2 editions published between 1989 and 1995 in English and held by 1 library worldwide
This is a final report describes briefly three accomplishments in the area of resonant tunneling through double-barrier devices made of GaAs/AL(x) Ga(1-x)As heterostructures. They are: (1) the first experimental demonstration of the importance of many-electron effect in transport through such devices, (2) a self consistent calculation to take into account the space charge effect and thus to extract spectroscopic information from the experimentally measured I-V characteristics, and (3) the first observation of an intrinsic electrical bistability.
Effect of Correlation on Signal Detection in Arctic Under-Ice Noise ( Book )
2 editions published in 1988 in English and held by 1 library worldwide
Signal detection in a large segment of non-Gaussian and non-stationary Arctic under-ice noise, which contains both high power narrow-band and impulsive components, is examined. It is shown that the correlation functions of sub-segments of data change significantly, and if ignored, can degrade the performance of the detector. For a false alarm probability of 0.05 and a known constant signal, the matched filter was on average 17.6% better than a detector designed assuming independent noise samples. It is also shown that pre-processing the data with an adaptive notch filter, then using the matched filter will result in a further improvement of about 6%. Additionally, the effect two different signal shapes have on the performance of the matched filter is examined. Keywords: Underwater sound d signals; Underice noise sound; Omnidirectional hydrophones.
Efficient Algorithms and Structures for Robust Signal Processing ( Book )
2 editions published between 1985 and 1986 in English and held by 1 library worldwide
The research efforts supported by AFOSR Grant AFOSR-84-0381 were directed towards development and analysis of robust estimation techniques for autoregressive (AR) and autoregressive-moving average (ARMA) models. Work on related system theoretic problems associated with parameter estimation problems for times series models and on square-root filtering for least squares state estimation applications was also carried out. Finally, an adaptive estimation technique for a class of piecewise (in time) stationary signals was developed. The motivation for our research arises from applications in signal processing including linear predictive singal modeling, signal detection, dynamic state estimation (Kalman filtering), and spectral analysis. The general goal of this research has been to put together ideas and techniques from statistics, signal processing, and system theory to bring new perspectives to such problems. Our research on various autoregressive modeling problems resulted from a desire to relax some of the assumptions made by previous researchers, in order to broaden the domain of application of the basic technique which has proved to be useful in a range of signal processing tasks. In particular, our efforts have been directed at the goal of obtaining allowing robust estimates in the presence of outliers in the observed signal and in modeling of signals whose spectral characteristics change abruptly from time to time.
Research into Self-Timed VLSI Circuits ( Book )
2 editions published in 1984 in English and held by 1 library worldwide
There are three major components to our project. The first is in the area of procedural design of VLSI circuits. The second is in the area of our census language, and the third is in the area of the testing of VLSI circuits. (Author).
Novel Digital Signal Processing and Detection Techniques ( Book )
2 editions published between 1980 and 1981 in English and held by 1 library worldwide
A number of results were obtained during the period 1 August 1979 to 30 July 1980. Studies were made of the implementation of narrowband digital filters with reduced roundoff error and limit cycle oscillations. Bounds on limit cycles of second order filters were derived for filters using error spectrum shaping. The performance of two sequential signal detectors were analyzed. A schemee for the computer generation of random sequences with a specified first order distribution and a specified autocovariance function is proposed and analyzed. A delta modulation like sampled analog filter structure is developed. The filter uses only coefficients O, +1, and -1, and can be fabricated as a programmable CCD filter. Work has begun on a further refinement of narrowhead spectrum analysis by direct decimation and on the use of recursive filters for decimation and interpolation.
Double Superlattice GaAs IR Transistors ( Book )
1 edition published in 1995 in English and held by 1 library worldwide
A superlattice structure can be incorporated into a quantum-well infrared detector as an electron bandpass filter to block electrons with energies higher or lower than the miniband energy. Electrons with energies inside the miniband can relax their energies to the lower edge of the miniband as they pass through the superlattice. Therefore, the superlattice not only filter the electron energy but also keeps the filtered electrons to a minimum energy. We have realized these expected advantages, greatly improved the detectivity of the device, and demonstrated the operation of a background limited IR transistor for T up to 90K. The research was carried out in these stages as described below.
Submillimeter Wave Spectroscopy of Heterojunction Superlattices: A Final Technical Report ( Book )
1 edition published in 1992 in English and held by 1 library worldwide
The general objectives of this research are to systematically investigate the interaction of electromagnetic radiation in the far infrared range with the charge carriers in semiconductor heterojunction superlattice structures. Experiments are performed on both the lattice-matched GaAs/Al sub XGa sub 1-xAs/GaAs heterojunction material structures and the strained-layer material of In sub xGa sub 1-xAs/GaAs heterostructure. In the former case, new electronic processes are discovered and their possible detector application is explored. In the latter case, the energy level structure is determined and the carrier dynamics are studied using the submillimeter wave spectroscopy.
Group II Cubic Fluorides as Dielectrics for III-V Compound Semiconductors ( Book )
1 edition published in 1989 in English and held by 1 library worldwide
The epitaxial growth of lattice matched Ca(x)Sr(1-x)F2/Gallium Arsenide and GaAs/Ca(x)Sr(1-x)F2 heterojunctions by molecular beam epitaxy is investigated. These heterojunctions are potential candidates for realizing opto- electronic devices involving III-V Compound Semiconductors. The composition x=0. 5 is chosen to minimize the lattice mismatch at room and growth temperatures. The fabrication of the layers involves the sequential growth of GaAs wafers of a GaAs buffer layer, a 2000-3000A Ca5SrF3 layer, and a top 500-3000A GaAs layer. The growth along the (100), (111), (511) and (711) orientations is investigated. Optimum growth temperatures range from 500 C to 550 C for the fluorides, and 550 C to 600 C for the GaAs. The orientation of the substrate is conserved throughout the three epitaxial layers. The bulk crystallinity, studied with ion scattering, is found to be excellent in the GaAs buffer layer, fair to good in the fluoride layer, and poor to fair in the top GaAs layer. The high Miller- index GaAs surfaces ((511), (711)) exhibit a regular stepped structure ((100) terraces) which contributes to the reduction of anti-phase disorder in the fluoride layer. It is also found that the (511) orientation is favorable for the growth of the top GaAs layer. Rough morphology and facetting at fluoride surfaces are identified as the main problems for the growth of high quality top GaAs layers. Post-growth thermal treatments and electron-beam exposure will be investigated as potential solutions. Keywords: Semiconductor/insulator/ semiconductor heterojunctions; Calcium compounds; Strontium compounds; Fluorides.
Near-Far Resistant Linear Multiuser Detection ( Book )
1 edition published in 1989 in English and held by 1 library worldwide
This dissertation studies linear detectors for Code-Division Multiple-Access channels perturbed by additive white Gaussian noise, under the assumption that the ensemble of user code waveforms is known to the receiver. In particular the near-far problem of Direct-Sequence Spread-Spectrum Multiple-Access channels, i.e., the problem of demodulating a weak transmitter in the presence of powerful interferers, is solved with a linear receiver. Two multiuser performance measures are used to quantify the performance degradation due to the presence of multiuser interference: The asymptotic efficiency, which is equivalent to bit-error-rate in the low background noise region, and the near-far resistance, which measures a detector's robustness to the near-far problem. Conventional single-user detection in a multiuser channel is not near-far resistant, while the substantially higher performance of the optimum multiuser detector requires exponential complexity in the number of users. We show that the near-far resistance of optimum multiuser detection is achieved by a linear receiver (whose complexity per demodulated bit is only linear in the number of users). The optimum linear detector for worst-case energies - the decorrelating detector - is found, along with existence conditions, which are always satisfied in the models of practical interest. Its implementation does not require knowledge of the received energies, its bit-error-rate is energy-independent, and it achieves optimum near-far resistance. (JHD).
Some Experiments in VLSI Leaf-Cell Optimization ( Book )
1 edition published in 1984 in English and held by 1 library worldwide
This paper describes a method for local optimization of VLSI leaf cells, using the parameterized procedural layout language ALLENDE 5. Tradeoffs among delay time, power consumption, and area are illustrated. Three different implementations of the 1-bit full adder are compared: a random logic circuit, a data selector, and a PLA. The fastest random logic 1-bit full adder has a time-power product about 1/3 that of the fastest data selector, and about 1/4 that of the fastest PLA. The 4-bit parallel adder is used to illustrate the effect of loading when leaf cells are combined. (Author).
Detectors for Multinomial Input ( Book )
1 edition published in 1983 in English and held by 1 library worldwide
Some Complexity Results in the Design of Deadlock-Free Packet Switching Networks ( Book )
1 edition published in 1979 in English and held by 1 library worldwide
Properties of the Maximal Correlation Function ( Book )
1 edition published in 1980 in English and held by 1 library worldwide
Comparison of LEED and Auger Data from Cleaved and Sputtered-Annealed InP(110) Surfaces ( Book )
1 edition published in 1980 in English and held by 1 library worldwide
Optimal time-domain synthesis by iterative methods ( Book )
1 edition published in 1965 in English and held by 1 library worldwide
An iterative procedure is presented which permits the determination of a rational transfer function in the Laplace transform variable s which is optimal with respect to given input and output time-functions. The optimal system of a particular order is defined as the one whose output when subjected to the known input function is nearest in the time integral square sense to the desired output function. The method is thus applicable to a number of problems involving the minimization of an integral square error. (Author).