The Structure of Amorphous Semiconductor: Metal Thin-Films

Edwards, Ann M. (1989) The Structure of Amorphous Semiconductor: Metal Thin-Films. Doctor of Philosophy (PhD) thesis, University of Kent.

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A transition from semiconducting to extend state conduction may be induced in certain amorphous semiconductor:metal alloys by increasing the metal concentration above a critical limit. Descriptions of the processes involved in such a transition have generally been based around investigations on electronic properties. However, without a knowledge of the atomic-scale structure of the alloys, it is difficult to ascribe a mechanism to an observed transition. In order to increase the understanding of such processes in semiconductor:metal systems, thin-film samples of three alloy systems (a-Si:Ni:H, a-Si:Sn:H and a-Ge:Au) have been prepared by rf co-sputtering over pertinent composition ranges, and micro-structural studies have been performed using extended X-ray absorption fine structure spectroscopy and other complementary techniques. For low metal concentrations (<20at.%), both a-Si:Ni:H and a-Ge:Au appear to consist of two separate phases: regions of an amorphous Ni:Si or a partially crystalline Au:Ge alloy being embedded in the remaining, modified amorphous matrix provided by a-Si:H and a-Ge respectively. In contrast, Sn atoms appear to substitute randomly into the a-Si:H network. The implications of these results for the interpretation of electrical conductivity data is discussed.

Item Type: Thesis (Doctor of Philosophy (PhD))
Subjects: Q Science > QC Physics
Divisions: Faculties > Sciences > School of Physical Sciences
Depositing User: Suzanne Duffy
Date Deposited: 11 Mar 2014 13:43 UTC
Last Modified: 29 May 2019 11:58 UTC
Resource URI: (The current URI for this page, for reference purposes)
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