The photoconductivity of thin (less than 100nm) films of hydrogenated amorphous material was measured as a function of time in order to monitor the defect density during remote inductively coupled plasma post-hydrogenation at room temperature, light-soaking (before and after post-hydrogenation) and isothermal annealing (after post-hydrogenation and light-soaking). The results were fitted to a stretched-exponential curve. A decrease in the photoconductivity during post-hydrogenation at room temperature was observed, and was related to the breaking of Si-Si weak bonds by individual H atoms. The initial equilibrium defect density recovered during thermal annealing. The stretched-exponential parameters of the photoconductivity were the same for isothermal anneals that were carried out after light-soaking and after plasma post- hydrogenation. This indicated that the defects which were introduced were of similar type in both cases. The stretched-exponential parameters were also the same for light-soaking before and after plasma post-hydrogenation. This suggested that post-hydrogenation did not alter the susceptibility of the material to light-induced degradation. The increase in H concentration during post-hydrogenation was measured by means of infra-red spectroscopy.

J.P.Conde, M.Gonçalves, P.Brogueira, V.Schotten, V.Chu: Physical Review B, 1996, 53[4], 1886-90