Optical properties of intrinsic hydrogenated amorphous silicon at high electric field

In this paper optical properties of intrinsic hydrogenated amorphous silicon (i ‐a‐Si:H) at high electric field are studied. A theoretical model for an absorption coefficient that predicts its increase at higher electric field has been developed based on additional electron transitions from lower occupied states to higher unoccupied states utilizing emission over or tunnelling through the potential barrier. Measurements of transmission were performed on a transparent conductive oxide (TCO)/i ‐a‐Si:H/TCO/glass test structure and confirmed the effect of increased absorption at increasing field. The trends between theory and experiment are in agreement, although the theoretical model overestimates the sensitivity of absorptance to electric field strength. The influence of secondary effects such as voltage drop across the TCOs, self‐heating and temperature dependence are discussed (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)