Reversible structural changes in discharge-produced amorphous silicon

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Abstract
This work studies the reversible, structural changes of undoped hydrogenated amorphous silicon films under prolonged illumination and thermal annealing. Experimental results from infrared spectroscopy showed that the strength of the stretch modes of SiH and SiH2 decrease more slowly in the initial stage and then more rapidly at about 1018 cm−3 spin density during prolonged illumination periods. On the other hand, the strength can be restored to its original value after a certain period of thermal annealing at 250 °C. These results are correlated with those obtained from electron paramagnetic resonance and photoconductivity measurements, in which the rate equations were analyzed to reveal the origin of recombinations responsible for the weak Si–Si bond breaking. An explanation is proposed in this study to illustrate the light-induced bond breaking and its repair.