DIFFERENCES BETWEEN LIGHT-INDUCED AND NATIVE MIDGAP STATES IN INTRINSIC HYDROGENATED AMORPHOUS-SILICON OBTAINED FROM DETAILED MODELING OF PHOTOCONDUCTIVITIES AND SUBBAND-GAP ABSORPTION

The nature and densities of states near-midgap of intrinsic hydrogenated amorphous silicon (a-Si:H) were derived from detailed numerical analysis of magnitudes and intensity dependence of both subband-gap absorption and steady-state photoconductivities. Self-consistent results were obtained for a wide range of intensities only with the introduction of defects states above midgap which are different from those in the annealed state. These states, which are not detected by CPM, have densities and electron capture cross sections which are greater than those of the nativelike defects associated with the dangling bond. This is consistent with the rapid decreases in photoconductivity that occur upon initial light soaking and previously reported evidence for two types of SWE defects.