Electrical and optical properties of rf-sputtered GaN and InN

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. © 1972 The American Institute of Physics.