Optical and structural analysis of GaN grown by remote plasma enhanced laser induced chemical vapour deposition

High quality polycrystalline gallium nitride (GaN) films have been grown by remote plasma enhanced laser induced chemical vapour deposition (RPE-LICVD) on sapphire, silicon, and quartz substrates at temperatures below 600 °C. Transmission spectra of the films indicate excellent properties with band gap 3.38 ± 0.02 eV. A yellow band-to-band transition at 2.2 eV is observed. X-ray diffraction patterns reveal the (0002) wurtzite reflection at 2θ = 34.6° is dominant. Raman spectra of the films are discussed with respect to the phonon frequencies and strain-related phenomena. Compositional analysis with heavy ion Elastic Recoil Detection shows stoichiometric nitrogen to gallium ratios and relatively small amounts of incorporated oxygen.