A STUDY OF DISCONTINUOUS THIN GOLD FILMS AND GOLD-SILICON MONOXIDE CERMETS
Date
1971-04
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ORCID
Type
Degree Level
Doctoral
Abstract
This thesis considers the mechanisms of conduction and nucleation in discontinuous thin metal films for application to thin film cermet resistors.
A review of previously suggested theories shows that only two are viable, the first based on a thermionic emission model, the second on an electrostatically charge activated tunneling one. It is shown that the accepted thermionic theory is in error and this is
corrected. The charge activated theory is extended to include the case of the oblate spheroidal shape of the metallic particles in a
discontinuous metal film and also the non-uniform distribution of field in the film.
Both theories are then evaluated in the light of appropriate experiments and both are shown to be capable of explaining qualitatively the phenomena of non-ohmic field effect and the possession of an activation energy. The variations in film conductivity under stress and upon exposure to air lead to the rejection of the thermionic model. Although full quantitative agreement of theory and experiment has not been reached, due to extreme difficulty in accurately determining film structures, most of the experimental results described are adequately accounted for by the charge activation model.
The origins of surface charge on the substrate, which is a cause of the oblate spheroid shape of the islands in discontinuous films, are determined, its effects are examined, and the necessary procedures to reduce it are discussed. A detailed discussion of several of the experimental techniques employed in the study is included.
An extension of the conduction theory to gold-silicon monoxide cermets is developed and the results are shown to be in qualitative agreement with the charge activated model. This comparison of theory and experiment serves to emphasize the existence of electron traps in the insulating phase and the radiation heating effects of the silicon monoxide deposition source and suggests directions in which this study could be usefully continued.
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Degree
Doctor of Philosophy (Ph.D.)
Department
Electrical Engineering