A model for some defect-related bound exciton lines in the photoluminescence spectrum of GaAs layers grown by molecular beam epitaxy

The sharp defect-related bound exciton lines originally reported by Kunzel and Ploog (1980,1981) in the low-temperature photoluminescence spectrum of the MBE-grown GaAs are interpreted in terms of excitonic recombination at a pair of shallow acceptors. It is proposed that the various lines in the spectrum correspond to different separations of the two defects in the pair with the lowest-energy line arising from nearest-neighbour pairs. A pronounced optical polarisation of the lines is also reported.