A COMPUTER-SIMULATION OF THE RECOMBINATION PROCESS AT COMPOUND SEMICONDUCTOR SURFACES AND HETERO-INTERFACES

The complex recombination process through quantum states at compound semiconductor surfaces and hetero-interfaces is analyzed in a unified manner on the computer, using the unified disorder induced gap state (DIGS) model. Recombination through uniformly distributed states at surfaces and hetero-interfaces, and that through U-shaped surface states at GaAs surfaces subjected to various surface treatments, are specifically analyzed. The result indicates that the effective surface recombination velocity is not constant, but is strongly dependent on the excitation intensity and the location of charge neutrality level, EHO. PL intensity enhancement after photochemical oxidation in water and sulfur treatments (Na2S, (NH4)2S) is shown to be not due to reduction of the durface states, but due to the generation of a fixed charge, whereas photochemical HCl treatment reduces the surface states significantly. © 1989.