Optical properties of GaN synthesized by implantation of nitrogen ions into GaAs

Implantation of N ions with doses of 3×1016 and 3×1017cm-2 and energies of 100 keV into semiinsulating (1 0 0) GaAs substrates has been performed in order to synthesize the GaN compound. The samples have been annealed in a furnace at 750 °C for 30 min in N gas flow or under GaAs powder and then characterized by 300 and 77 K cathodoluminescence, infrared reflection, Raman spectroscopy and secondary ion mass spectroscopy measurements. All optical techniques have detected the presence of GaN phase in the samples. No noticeable dependence of CL spectra on annealing conditions leading to different As and N losses from the surface has been observed. SIMS measurements have been performed to show N atom redistribution after annealing. The results of the study are consistent with the presence of buried layers with differently oriented GaN nanocrystals.