Light-induced effects in hydrogenated amorphous silicon films grown from high hydrogen dilution of silane

초록

Light-induced effects have been studied in a series of hydrogenated amorphous silicon (a-Si:H) films grown from different hydrogen (H,) dilution ratio of silane, R (= [SiH4]/([H-2] + [SiH4]). The light-induced changes were monitored using photoconductivity and sub-gap absorption measurements, It is found that the light-induced changes are nearly independent of H-2 dilution ratio between R = 100% and R = 40% but the change rapidly decreases with decreasing the R. For the high H-diluted films (less than R approximate to 10%) the change is so small as to be negligible, despite large hydrogen content, The hydrogen evolution spectra are decomposed into two components: low and high temperature peaks. It is found that there is a close correlation between the volume fraction of the integrated intensity of the low temperature peak and the improvement of stability. From these results it is suggested that the hydrogen clusters play a dominant role in improving the stability of high H-2-diluted a-Si:H films. (C) 2002 Elsevier Science B.V. All rights reserved.

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