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Date of Award

8-1991

Degree Type

Thesis

Degree Name

Doctor of Philosophy (PhD)

Department

Materials Science

Supervisor

A.H. Kitai

Abstract

Thin films of ZnS and ZnO(1-x)Sx were prepared by electrodeposition and chemical vapour atomic layer deposition (CVALD), respectively. This represents the first effort to apply the technique of electrodeposition to ZnS for the purposes of electroluminescence. This is also the first time thin films of ZnO(1-x)Sx were grown by CVALD and represents the first analysis of how the films properties vary with a known stoichiometry. Characterization methods performed on the thin films include: Auger spectroscopy, Rutherford backscattering spectroscopy, scanning electron microscopy, x-ray powder diffraction, Hall measurements and uv/visible transmittance. The as electrodeposited films were nearly stoichiometric but conductive and oriented in a <200> direction. After annealing the films became discontinuous and lost their crystallinity, but their absorption characteristics more closely resembled that of evaporated films. Ion implantation with Mn was successful and the films exhibited yellow-orange cathodoluminescence. The value of x in the formula ZnO(1-x)Sx could be varied from 0 to 0.95 by changing the amount of hydrogen sulphide admitted to the reaction chamber. Films with values of x near 0 grow in the <200> direction (of ZnO) and have a fine grained structure. As the value of x increases the films become more and more amorphous but split into a two phase structure close to x = 0.55. At this point the films exhibit a minimum bandgap. As x increases further the films become one phase again and become oriented into the <111> direction of ZnS. The cathodoluminescent characteristics of these films also change with x. When x is zero the films appear to luminescence green or yellow depending on the deposition temperature. Even 5% S removes this luminescence however and the spectrum is dominated by a peak in the red. This peak steadily decreases then increases again as x increases.

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