Microstructure and the light-induced metastability in hydrogenated amorphous silicon

Using a parameter obtained from infrared measurements of the silicon-hydrogen stretch mode, the amout of light-induced degradation in hydrogenated amorphous silicon (a-Si:H) has been explored as a function of the amount of microstructure present in our samples. We find that samples with more microstructure, and also more bonded hydrogen, show an increased light-induced effect. At the same time, the volume density of states in the initial (annealed) state remains virtually unchanged. We discuss how the present results relate to existing models proposed to describe the light-induced effect.