Existence of deep acceptors in Ga- and B-implanted GaAs after close-contact annealing

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Abstract
Photoluminescence studies have been carried out on liquid-encapsulated Czochralski GaAs crystals. Two wafers (labeled P1 and P2) originating from the same ingot have been investigated. After close-contact annealing, the presence of a ≂64-meV deep acceptor was observed in P1-type samples only. After gallium implantation at increasing doses and annealing, the presence of the ≂64-meV level is also observed in P2-type samples. Boron implantation at increasing doses also generated the 64-meV level and, in addition, the ≂77-meV acceptor level, often ascribed to GaAs. Using scaling arguments the 64-meV level is tentatively ascribed to the first level of a double-acceptor defect. Owing to the stoichiometric imbalance induced by implantation and annealing and the specific influence of boron implantation, the ≂64- and ≂77-meV levels are tentatively ascribed to GaAs and BAs antisite defects, respectively.