Photoluminescence from self-assembled GaAs inclusions embedded in a GaN host crystal

We report on observation of photoluminescence in 1.2-1.4 eV spectral range from As-doped GaN layers grown by plasma-assisted molecular beam epitaxy. We attribute this emission to recombination in GaAs inclusions formed during the growth process in the GaN(As) layers. This near-infrared emission is efficient under UV photoexcitation, but its intensity is low for excitation energies below the band gap of GaN. Low-temperature photoluminescence spectra reveal a set of sharp emission lines with maxima from 1.516 eV to 1.436 eV. We attribute some of these sharp lines to the emission of excitons bound to nitrogen incorporated into the GaAs crystallites and also to their GaAs-like optical phonon replicas. Photoluminescence excitation spectra show a series of maxima, which can be attributed to the formation of bound and free excitons and also to the formation of excitons with the simultaneous emission of GaAs-like optical phonons.