Abstract:In this investigation, we added some new findings and interpretations on the behaviors of both electrical conductivities and optical absorption spectra upon adsorption of atmospheric molecules in microcrystalline silicon films (µc-Si:H). The photo conductivity followed similar decay-recover processes upon air exposure-thermal anneal cycles as did the dark conductivity. The dark and photo conductivities decay according to a stretched-exponential function with time upon air exposure. The absorption spectra showed a reduced defect absorption for the films at air exposed state compared with those of at thermal annealed state. There is a one-to-one correspondence between atmospheric adsorption in µc-Si:H and bias-stress induced instabilities in a-Si:H thin film transistors(TFTs).