X-ray spectroscopy of the valence band electronic structure in high-deposition-rate a-Si:H

The electronic structure of a-Si:H samples prepared by either the expanding thermal plasma (ETP) technique or standard plasma-enhanced chemical vapour deposition (PECVD) has been examined by means of photoemission and X-ray emission spectroscopies. Small changes have been seen only on the s state distributions. Particularly, the intensity of a structure present in the gap at about 0.5 eV from the valence band edge varies from the PECVD to the ETP samples. The observed hole mobility differences between the samples prepared by either method do match the differences in the extended character of these defect states in the gap.