Sharp-line photoluminescence of GaAs grown by low-temperature molecular beam epitaxy

We report sharp-line photoluminescence spectra from GaAs layers grown by low-temperature molecular beam epitaxy. The photoluminescence consists of no-phonon line (A) at 1.467 eV and associated phonon sidebands of both lattice and localized vibrational modes. Photoluminescence features, layer growth condition, and heat treatment of the layer for the complex responsible for the photoluminescence spectrum are found to be consistent with the C3v symmetry of the complex. The spectra reveal five local phonons having stronger intensity compared to the lattice phonon. We propose that the complex is due to the nearest-neighbor VGa-Asi pair.