RECOMBINATION IN SEMICONDUCTOR ELECTRODES - INVESTIGATION BY THE ELECTRICAL AND OPTOELECTRICAL IMPEDANCE METHOD

The electrical impedance and the optoelectrical impedance due to elect ron-hole recombination in the depletion layer and at the surface of a semiconductor electrode are calculated. It is shown that both types of impedance follow from a common formula for the ac recombination curre nt density in the external circuit, which is derived from first princi ples. It is found that both the electrical and optoelectrical impedanc e methods provide the same information about recombination. Both metho ds enable one to distinguish surface recombination from recombination in the depletion layer. The theoretical results are compared with the electrical and optoelectrical impedance results measured at GaAs and C dS photoanodes.