[PDF] Optical Real Time Signal Processors And Semiconductor Surface And Semiconductor Electrolyte Interface Study Using Acoustic Surface Wave eBook

Author : Pankaj K. Das
Publisher :
Page : 19 pages
File Size : 45,53 MB
Release : 1981
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The research work can be broadly classified into four categories: (1) a new method for the determination of electrical surface properties of semiconductors using acoustic surface wave delay lines, (2) a new method for the determination of electrical properties of semiconductor-electrolyte interface, (3) optical signal processing using surface acousto-optic interaction, and (4) studies on hot electron properties of semiconductors. The method of surface property determination is sensitive and simple and requires no physical contact with semiconductor surface. The SAW probing technique for electrical characterization of semiconductors has been performed at low temperature down to 77 K. Results obtained with GaAs agree with the theoretical expectations. Oxides have been anodically grown on GaAs and interface properties are being evaluated using the SAW probe. The activation of ion-implanted impurities in silicon by thermal annealing is being monitored by the SAW probing technique. Numerical computations of the transverse acoustoelectric voltage (TAV) have been performed which can be used to quantitatively evaluate the semiconductor properties non-destructively from the experimental TAV data. In connection with semiconductor-electrolyte interface study, the electrical properties of CdS-NiCl2 interface have been determined using the surface acoustic wave technique.

Author : Herve Renson Gautier
Publisher :
Page : 190 pages
File Size : 24,48 MB
Release : 1975
Category : Acoustic surface acoustic wave devices
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This work presents an experimental and theoretical study of the interactions between acoustic surface waves on a piezoelectric insulator and charge carriers in a neighboring semiconductor separated by a small airgap; and the application of these phenomena to signal processing and optical imaging. Although the two media are mechanically isolated, the electric field associated with the surface waves penetrate into the semiconductor and interact with its charge carriers. This interaction is nonlinear, and, in the case of two oppositely propagating surface waves, real time convolution is performed. A new theory of the convolution interaction, taking into account the possible presence of a depletion, inversion or accumulation layer at the surface of the semiconductor, resulting from a built-in or applied dc field is presented. Experimental measurements for both n- and p-type Silicon on Lithium Niobate systems are in very good agreement with this theory, and they lead to a novel technique of measurement of the surface state distribution on semiconductors. The silicon on lithium niobate structure used gives rise to one of the largest convolution efficiencies reported to date. Several signal processing applications are presented. They show the versatility of the device which can be employed as a programmable filter or a parametric processor. In addition, the first autocorrelation is demonstrated by cascading two convolvers. The acoustic convolver was adapted for the scanning of optical images.

Author : D. Schumer
Publisher :
Page : 164 pages
File Size : 33,14 MB
Release : 1977
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The theory of the interaction of coherent light with surface acoustic waves and an experimental demonstration of the application of the interaction to new devices are presented. The analysis, based upon classical electromagnetic theory and a phenomenological formulation of the photoelastic effect, is applied to the piezoelectric material LiNbO3, and provides good agreement with previously published experimental data. Explicit account is taken of the linear electro-optic and linear elasto-optic contributions to the interaction. The experimental demonstration of applications is restricted to the side-entry technique, an interaction configuration providing the longest interaction length between a surface acoustic wave and unguided optical wave. The relative merits of this configuration are discussed. New experimental results for the real-time side-entry convolver employing optical heterodyning include autocorrelation of Barker codes, ambiguity function generation, demonstration of a parallel acoustic track geometry to inhibit reflections, and measurement of diffraction characteristics for polarized light. Results are given for the correlation of a time varying light intensity distribution with an electrical signal, and the application to an optical communication system is indicated. The scanning of one and two dimensional black and white transparencies is performed, and the extension to color image scanning is demonstrated. All experiments are performed using Y-cut Z-propagating LiNbO3. Acoustic frequencies employed range from 45 MHz to 100 MHz. Laser sources are HeNe and Ar. Devices are analyzed and discussed with reference to the diffraction integral of scalar diffraction theory.

Author : D.P. Morgan
Publisher : North Holland
Page : 456 pages
File Size : 26,89 MB
Release : 1985
Category : Computers
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Recent years have seen the emergence of a wide variety of electronic devices making use of surface acoustic waves in solids. This book focusses on the devices of greatest current interest and on the principles underlying them. An introductory survey is followed by chapters on acoustic wave fundamentals, electric excitation, transducers, multi-strip couplers and propagation effects. The interdigital transducer is emphasised since it is a key element in most devices. The remaining chapters - about half of the book - describe practical devices including delay lines, bandpass filters, chirp filters for pulse-compression radar (including reflective array compressors), convolvers and oscillators. For the main devices the text includes design principles, second-order effects, practical performance and, where appropriate, the role of the device in system applications. Some of the more mathematical details are relegated to Appendices, which include electrode interactions in transducers, sampling theory, the electrostatic element factor and the required relationships from Fourier analysis. A classified list of over 500 references is provided.The book will be of interest to engineers developing surface-wave devices, and to those using the devices in practical systems. It is also very suited for university courses or research work.