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.