Low reflectance sputtered vanadium oxide thin films on silicon

• V2O5 (major phase) thin films of thickness ∼21 nm to ∼211 nm developed on Si.
• Low (∼1–2%) interference minima in reflectance spectra recorded at UV–VIS region.
• Almost constant and linear reflectance behavior observed at NIR region.
• Refractive index of V2O5 on Si estimated as 2.9–3.27.
• Extinction coefficient decreases as increase in thickness of the film.

Vanadium oxide thin films on silicon (Si) substrate are grown by pulsed radio frequency (RF) magnetron sputtering technique at RF power in the range of 100–700 W at room temperature. Deposited thin films are characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques to investigate microstructural, phase, electronic structure and oxide state characteristics. The reflectance and transmittance spectra of the films and the Si substrate are recorded at the solar region (200–2300 nm) of the spectral window. Substantial reduction in reflectance and increase in transmittance is observed for the films grown beyond 200 W. Further, optical constants viz. absorption coefficient, refractive index and extinction coefficient of the deposited vanadium oxide films are evaluated.