Optical Observation of Inhomogeneity of Chromium-Doped Semi-Insulating GaAs

Abstract

The macro- and micro-scale inhomogeneity of semi-insulating GaAs grown by the liquid-encapsulated Czochralski (LEC) method was investigated using three kinds of optical scanning measurement: near-band-edge luminescence, intrinsic photocurrent, and near-infrared photoabsorption. The photoabsorption measurement was used to obtain the distribution of Cr. The correlation found between the luminescence and photocurrent profiles implies that the defect center density is relatively small in the high dislocation density region. The low correlation between the photoabsorption and luminescence profiles indicates that the distribution of Cr is not dominated by dislocations. The possibility of interaction between dislocations and defects in LEC-GaAs was studied by carrying out a heat treatment experiment.