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Determination of the Density of Gap States in a-Si:H from Studies of Semiconductor/Oxide Multilayer Films

Published online by Cambridge University Press:  26 February 2011

R. B. Jones  and
G. Moddel
R. B. Jones
Affiliation:
Department of Electrical and Computer Engineering, University of Colorado, Boulder, CO 80309-0425
G. Moddel
Affiliation:
Department of Electrical and Computer Engineering, University of Colorado, Boulder, CO 80309-0425
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Abstract

A method for determining the density of states [N(E)] in the upper half of the energy gap in hydrogenated amorphous silicon (a-Si:H) is proposed and experimental results are simulated. The method involves the growth and measurement of the planar conductivity in multilayer films in which each layer is separated by a thermally grown oxide. Band-bending occurs at each interface throughout the film thickness. The conductivity parallel to the layers in the films is a function of the band-bending, which in turn depends on N(E), in the energy range through which the Fermi level is shifted. Computer simulations of the oxide-induced band-bending have been used to generate curves of the conductivity as a function of layer-thickness for various N(E). By matching experimental results with the simulation curves, the N(E) may be deduced. The simulations have also been used to show the difference between the bulk conductivity activation energy and effective activation energy which is measured in films influenced by a surface oxide.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 95: Symposium E – Amorphous Silicon Semiconductors--Pure and Hydrogenated , 1987 , 393
Copyright
Copyright © Materials Research Society 1987

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