Equilibrium and light-induced gap-state distribution in a-Si:H

A unified approach to describe the density and distribution of gap-states under general non-equilibrium conditions is based on structural equilibration between Si-Si bonds, Si-H bonds and Si dangling-bonds. Key factors that determine both the equilibrium and metastable defect structure are identified as free electron-hole concentrations and resulting electronic occupation functions which hold during the structural equilibration process. The model is shown to account for the majority of experimental data regarding equilibrium and saturated defect densities, such as their dependence on temperature, illumination intensity, band gap, hydrogen content, and tail slope