A POSSIBLE MECHANISM FOR IMPROVED LIGHT-INDUCED DEGRADATION IN DEUTERATED AMORPHOUS-SILICON ALLOY

We have studied light-induced photoconductivity degradation in an intr insic hydrogenated and deuterated amorphous-silicon (a-Si) alloy. Deut erated a-Si turns out to be more stable under light exposure. A possib le mechanism is proposed to explain this phenomenon. It is attributed to the highly efficient coupling between the localized Si-D wagging mo des (similar to 510 cm(-1)) and the extended Si-Si lattice vibration m odes (similar to 495 cm(-1)). The energy released from electron or hol e capture at silicon dangling bonds causes localized vibrations of nea rby Si-D bonds. The energy dissipates quickly to the background lattic e and a higher recombination rate at local sites is needed in deuterat ed a-Si than in hydrogenated amorphous silicon to accumulate enough en ergy to break the nearby weak bonds. (C) 1997 American Institute of Ph ysics.