Photoluminescence determination of the nonuniformity of Fe, Zn, and other centers in undoped semi-insulating liquid-encapsulated Czochralski GaAs

Abstract

2-K photoluminescence was used to determine the amount of nonuniformity present in undoped semi-insulating GaAs bulk substrate materials grown by the liquid-encapsulated Czochralski method. The relative photoluminescence intensities of the intracenter (5T2−5E) transition of the Fe2+ state, the near-band-edge transitions, and the Zn peaks, measured across the wafer diameter, show almost the same ‘‘W’’ pattern. The deep-center bands at 0.63 and 0.77 eV were also measured. Possible mechanisms of the photoluminescence intensity variation are discussed. In the materials used, a predominant shallow acceptor was observed to be Zn.