Optical properties of textured V2O5/Si thin films deposited by reactive magnetron sputtering

Abstract

Thin films of V2O5 were deposited on Si substrates by reactive DC magnetron sputtering of vanadium metal target in Ar/O2 low-pressure gas mixture. The phase composition of the films was examined with reflection high-energy electron diffraction (RHEED) at 65keV. The presence of V2O5 textured polycrystal with preferencial orientation of [100] was found for the range of 32.7–40.8% O2/(O2+Ar) ratio. The films are polycrystal without pronounced ordering for the range of 40.8–48.9% O2/(O2+Ar) ratio. Optical characterization of the films was produced with laser ellipsometry (λ=0.6328μm) and reflection spectra measurements. For V2O5 film deposited at 32.7 O2/(O2+Ar) ratio a uniform refractive index profile was found with n=2.67, optical absorption coefficient k=0.0011 and thickness d=165.0nm. These optical parameters are very reproducible and weakly dependent on gas mixture composition within the range pointed above. Optical anisotropy of V2O5 film has not been detected. The thickness of the transition layer at the V2O5/Si interface has been estimated to be ∼20nm. The wear resistance of the oxide films was tested with sand-bombardment method and good mechanical stability of the samples has been confirmed.