Influence of illumination during annealing of quenched defects in undoped amorphous silicon

Abstract

Measurements of isothermal relaxation of metastable defects induced by thermal quenching in undoped a-Si:H films are reported in the high-temperature range. During the relaxation studies following successive quenches from 250 \ifmmode^\circ\else\textdegree\fi{}C, a white-light illumination corresponding to various photoexcitation rates G was applied. Increasing G first increases the rate of annealing of defects to a maximum value, then decreases it and for higher G the annealing rate becomes lower than the dark annealing rate. The implications for kinetic models of creation and recovery are discussed. A model including both nondispersive and dispersive behaviors and a term-GN (defect density) to take account of light-induced recovery fits the present experimental data as well as a set of other experiments.