Applied Physics Letters · 1972 · 177 citations · 0 references
Natural SciencesMaterials EngineeringMaterials ScienceElectronic MaterialsSemiconductor MaterialsThin FilmsOptical Properties Of SemiconductorsOptical Thin FilmsSemiconductor PhysicsSemiconductor Thin FilmsThin Film Electrical PropertiesThin Film Optical PropertiesGallium NitrideGallium Nitride (Gan) MaterialsNitride Thin FilmsNitrides Thin FilmsOptical Absorption CoefficientOptical PropertiesRefractive Index DispersionSurface Optical Properties
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.