ON THE LACK OF OBSERVABLE LIGHT-INDUCED H DIFFUSION NEAR ROOM-TEMPERATURE

A 5-day, high-intensity (9 W cm(-2)), red-light soak of a-Si:H at 65 d egrees C yields no detectable H diffusion in a tracer experiment. A ne w upper bound to the light-induced diffusion coefficient at a temperat ure so low that thermal diffusion is negligible is found. The null res ult found here is incompatible with models in which H emission from Si -H bonds is proportional at all times to both the light intensity and the metastable defect creation rate. However, this result is compatibl e with the model proposed by Santos et al. in which both H emission an d metastable defect creation are proportional to the product of the fr ee electron and hole densities, In this model, this result implies tha t fewer than 500 H emissions occur per created metastable defect.