Correlation between improved stability and microstructural properties of a-Si:H and a-Ge:H

In this paper we report on comparative investigations concerning the stability of glow discharge and hot wire deposited a-Si:H films. Using spectroscopic ellipsometry measurements and a data interpretation based on a tetrahedron model we investigated the microstructural properties of the films. We found that the stability of a-Si:H films is significantly increased by a deposition process guided in a way that high quality material can be grown with high density and low hydrogen content. The a-Si:H results are confirmed by similar results obtained on sp-a-Ge:H. For the first time we have shown that metastability is not connected with the existence of surface like (SiH/sub 2/, (SiH)/sub x/) hydrogen bonding configurations.