ESR STUDIES ON A-SI-H - EVIDENCE FOR CHARGED DEFECTS AND SAFE HOLE TRAPS

Comparisons of electron spin resonance (ESR) light-induced ESR (LESR) and photo-modulated ESR (PMESR) indicate the existence of a shallow de fect level near the valence band which functions as an effective safe hole trap (SHT). Evidence for this state is found both in the annealed state (state A) and is observed to increase with light soaking. The h ole dominated LESR and PMESR lineshapes also require the presence of l arge densities of charged defects in order to account for the 'ESR inv isible' electrons. Observing the changes in the PMESR and LESR signals with the movement of the quasi-Fermi level by varying temperature and light flux confirm these ideas.