Kinetics of the generation and annealing of deep defects and recombination centers in amorphous silicon

Abstract
The number of deep defects (as measured by sub‐band‐gap optical absorption) and the number of recombination centers (as measured by steady‐state photoconductivity) in high quality undoped hydrogenated amorphous silicon are monitored as the film undergoes light‐induced defect generation and thermal annealing (the Staebler–Wronski effect). The kinetics of the growth in the density of deep defects agree well with the kinetics of spin centers reported by Stutzmann, Jackson, and Tsai. [Appl. Phys. Lett. 4 5, 1075 (1984)]. The density of recombination centers is directly related, though not simply proportional to, the density of deep defects; as samples are annealed, the recombination center density drops much more quickly than the total defect density. This behavior is shown to arise if the distribution of defect energy levels corresponds to a distribution of defect annealing energies.