By using a low-temperature micro-photoluminescence method, an investigation was made of the optical properties of oval defects in a layer which had been grown by means of molecular beam epitaxy. The photoluminescence spectra of the oval defects exhibited new distinct peaks which had narrow widths (0.0005eV) and strong intensities. The excitation power-dependence and photoluminescence image measurements suggested that the peaks were due to the recombination of excitons bound to defects. The photoluminescence image of the free-exciton luminescence clearly revealed the features of a pair of asymmetrical oval defects; each of which had a pyramidal structure that consisted of stacking-fault planes.

Microphotoluminescence of oval defects in a GaAs layer J.Kasai, M.Kawata: Applied Physics Letters, 1998, 73[14], 2012-4