Spectral dependence of the squared average optical transition matrix element associated with hydrogenated amorphous silicon

Using an empirical model for the density of states functions, in conjunction with an elementary model for the optical transition matrix elements, the spectral dependence of the squared average optical transition matrix element associated with hydrogenated amorphous silicon was evaluated. It was predicted that this squared average matrix element saturates at and beyond the mobility gap, decreases sharply just below the mobility gap as the photon energy is diminished, and then saturates at sufficiently low photon energies. The value of the squared average optical transition matrix element at low photon energies depends on the density of localized electronic states. The results suggest that a careful experimental measurement of the spectral dependence of this matrix element will provide one with a direct means of determining the position of the mobility gap of this semiconductor. (C) 2003 American Institute of Physics.