Reinterpretation of degradation kinetics of amorphous silicon

Abstract
Generation of light-induced metastable defects in amorphous Si:H(a-Si:H) is shown to follow the same stretched exponential (SE) that describes relaxation of thermally induced metastability at room temperature for a simple case. Apparent power laws derived from the central part of the SE are (time)0.3 and (intensity)0.6, agreeing well with the (time)1/3 and (intensity)2/3 dependences often reported in the mid range of defect density, thus providing an alternative description of defect generation. The SE link between light-induced and thermally induced instabilities suggests that the thermal effects are also due to defect processes, and offers an alternative defect-based explanation to a macroscopic ‘‘structural relaxation’’ or ‘‘glass transition.’’