DANGLING-BOND RELAXATION AND DEEP-LEVEL MEASUREMENTS IN HYDROGENATED AMORPHOUS-SILICON

We present a new perspective on defect levels in hydrogenated amorphou s silicon (a-Si:H) that unifies relaxation effects inferred from two r ecent experiments. In particular, we show how earlier calculations of dangling-bond relaxation can account for both the level deepening effe ct reported in transient capacitance measurements and the shallowing e ffect reported in transient photocurrent measurements under optical bi as. The former is due to dangling-bond relaxation toward a pyramidal b onding configuration, and the latter to relaxation toward a planar con figuration. We comment on the many-body nature of the remarkably slow kinetics of defect relaxation.