Investigation of dislocations in GaAs using cathodoluminescence in the scanning electron microscope

Abstract

Electrically active dislocations in Si-doped (100) GaAs substrates were observed using the cathodoluminescence (CL) technique in the scanning electron microscope (SEM). CL contrast profiles were experimentally obtained from the dislocations at different beam energies. Based on the CL model for localized defects in semiconductors developed earlier by Pey, the depths of the dislocations were found by locating the beam energy at which maximum CL contrast occurred. A preferential etching technique for (100) GaAs was employed to reveal the dislocations and to measure their depths. The etched depths obtained were compared to the predicted results from the theoretical model developed. The discrepancies in the results were attributed to a Cottrell atmosphere of point defects around the dislocation core.