SAFE HOLE TRAPS - A SOURCE OF METASTABLE LIGHT-INDUCED DANGLING BONDS IN A-SI-H

We apply a newly developed technique to determine ‘safe hole trap’ distributions in a-Si: H from secondary photocurrent transients. Because of changes of the safe hole trap distributions caused by light-soaking and subsequent anneals, we suggest that hole traps located 0.4-0.5 eV above the valence-band edge are the source of metastable dangling bonds induced by light-soaking at room temperature. At 163 K, four times as many safe hole traps are lost as for the light-soaking at room temperature. During annealing experiments, recovery of safe hole traps converted at 163 K is much faster than the recovery of safe hole traps converted at room temperature. We conclude that the exact configuration for lattice-relaxed metastable defects originating from safe hole traps depends on the temperature at which they are formed. © 1990 Taylor & Francis Ltd.