A Comparative Study of the Electronic Stability of Hydrogenated Amorphous Silicon and Silicon-Germanium Alloy Material

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Abstract
The electronic stability of a-Si:H and a-Si1-x Ge x :H films of different preparations has been investigated by keV-electron irradiation. Employing an electron dose of about 60 J/cm2, a metastable defect density near its saturation value was created. It was found that a-Si:H films exhibiting a high stability, if bulk sensitive measurement techniques (CPM, conductivity measurements) are applied, still have quite a large number of stable surface defects (detected by PDS) whose concentration is raised by irradiation. a-Si1-x Ge x :H alloy films are obviously more stable than pure a-Si:H films, whereby the relative stability increases with the Ge content x. Alloy films containing a small amount of germanium (≈5%) could be of special significance for practical application. The electronic properties of this material are almost identical to those of a-Si:H but the electronic stability is increased.