GaN and InN thin films were grown on sapphire, silicon, and metallic substrates using rf sputtering at temperatures of 25–750°C and presputtering vacuum of 10−8 Torr. The GaN films were high in resistivity (> 108 Ω cm), but the InN layers were highly conducting with an electron concentration of 7×1018 cm−3. The refractive index for GaN ranged from 2.1 to 2.4 at long wavelengths and was dispersive below 8000 Å; the index for InN is higher, 2.9. The absorption coefficient was measured from wavelengths of 2 μ to 2000 Å.