Stable, Metastable and Charged Dangling Bonds in Transient Light-Induced ESR of Undoped a-Si:H

Transient light-induced electron spin resonance (LESR) at 120 K, has been used to investigate potential differences between intrinsic (stable) and light-induced (metastable) defects in a-Si:H through changes in the line shape. Previously, we have reported that when the line shape is decomposed into broad and narrow components, the narrow component decreases dramatically, relative to the broad component, with increasing light-soaking time. The present results indicate, however, that similar changes are not observed when the defect density is increased by changing deposition conditions or by high-temperature annealing. A dangling-bond-conversion process involving charged dangling bonds is proposed to explain these changes. We suggest that stable and metastable defects play different roles in transient LESR and may occupy different energy positions in the gap of a-Si:H.