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A European Adventure In Amorphous Materials: From Past to Future

Published online by Cambridge University Press:  17 March 2011

Ionel Solomon
Ionel Solomon*
Affiliation:
Ecole Polytechnique, Laboratoire P.M.C. F-91128 Palaiseau cedex, France
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Abstract

The early work on amorphous silicon in Europe was dominated by the activity of the Dundee group, who demonstrated the feasibility of substitutional doping, in contradiction with previous theories which denied the possibility of doping disordered semiconductors. Also, the role of hydrogen in this new “good” disordered semiconductor was not immediately accepted, and the controversy was finally settled by the crucial experiment of post-hydrogenation by D. Kaplan. It is little known that this process of post-hydrogenation, currently used for the improvement of devices, was covered by a patent, which turned out to be quite inapplicable!

The high hopes raised by this “new” material, in particular for photovoltaic applications, rendered the field highly competitive, resulting in a surprising neglect of the basic principles of physics. A striking example is the sweeping under the rug of the effect of band bending at the surface of intrinsic a-Si:H. This effect makes the surface much more conducting than the bulk, rendering a large number of published transport measurements in planar geometry completely meaningless.

Research in Europe has been less application-oriented than research in USA and Japan, but on a small scale it was not completely absent from industrial applications to photovoltaics; a start-up adventure “a la French” is described. The problem of disordered materials is one of the timely solid-state topics, to continue to be a major subject of materials research in the near future. In that respect, amorphous silicon is an exemplary system, and the “hydrogen glass” picture, pioneered by R. A. Street et al., is an open field of research for the improvement of disordered semiconductors.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 609: Symposium A – Amorphous & Heterogeneous Silicon Thin Films – 2000 , 2000 , A17.3
Copyright
Copyright © Materials Research Society 1999

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References

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