Changes in the Density of States in a-Si:H with the Generation and Annealing of Light-Induced Defects

Abstract

Through sub-bandgap absorption spectra and photoconductivity measurements of high-quality hydrogenated amorphous silicon (a-Si:H), changes in the electronic density of states with light-soaking and subsequent annealing are qualitatively described. Included is a more complete understanding of the role of deep defects as recombination centers. In this way, the simple power laws of Stutzmann, Jackson, and Tsai for the light-induced degradation of defect density and photoconductivity are. retained in the modified forms Evidence is also presented that the states closest to midgap, those states that act as effective recombination centers, are the first to anneal.