Excitons and light-induced degradation of amorphous hydrogenated silicon

Excitonic states involved in electronic transport of undoped amorphous hydrogenated silicon (a-Si:H) are observed using spin-dependent photoconductivity (SDPC). Upon light soaking the excitonic signal decreases with regard to the SDPC signal due to recombination via dangling bonds. It has been suggested that excitonic tail-to-tail recombination leads to metastable defect creation in a-Si:H. Our experimental results are shown to be consistent with this model.