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ANALYSIS OF HIGH-FREQUENCY CHARACTERISTICS OF PLANAR COLD CATHODES

by KRISHNAN, RAJESH

Abstract (Summary)
The possibility of surface emitting cathode, which operates at room temperature, is attractive due to its compactness and reduced weight. Such cathodes, known as cold cathodes, can be used in a variety of electronic devices, including microwave vacuum transistors and tubes, pressure sensors, thin film displays, high temperature and radiation tolerant sensors, among others. Recently, M.Cahay and collaborators have proposed a new cold cathode emitter concept, making use of rare-earth sulphides to reach negative electron affinity at the surface. In this thesis, we investigate two unchartered areas in the physical operation of these cathodes which entails a development of a small signal equivalent circuit of the cathode and the effects of noise (mostly due to shot noise of the injecting contact) on the anode current fluctuations. We find that the efficient direct modulation of the anode current with a small AC signal across the CdS layer is possible. For an InP/CdS/Las cold cathode, the degree of electron beam prebunching is dependent on the cathode to anode spacing but is found to be tunable up to frequency well within the K-band for cathode to anode spacing of a few microns. We also have used an Ensemble Monte-Carlo code to study effects of shot noise, in the anode current, in planar Metal/CdS/LaS cold cathodes. We have identified device parameters and biasing conditions for which regime of shot noise suppression but also shot noise enhancement in the anode current fluctuations can be observed for the same cathode.
Bibliographical Information:

Advisor:

School:University of Cincinnati

School Location:USA - Ohio

Source Type:Master's Thesis

Keywords:negative electron affinity shot noise effect cold cathode ac equivalent circuit monte carlo simulation

ISBN:

Date of Publication:01/01/2003

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