Published online by Cambridge University Press: 01 February 2011
Light soaking for short durations and thermal quenching produce metastable states having a higher dark current, higher photo current, a larger photoluminescence and a smaller electron spin resonance signal in porous silicon (PS). Long exposures, however, have the opposite effect. All metastabilities can be removed by annealing at 150°C (1 h), but not by exposure to infrared light. Micro-Raman spectroscopy shows the presence of a-Si:H in the PS sample. However, a closer look shows that our results can not be explained in terms of a-Si:H alone. Our experiments suggest that structural changes involving the movement of hydrogen present on the surface of PS or on PS/a-Si:H interface may be responsible for these effects.