Exploring the oxygen effect on optical properties of amorphous vanadium oxide thin films

The optical properties of amorphous vanadium oxide (a-VxOy) thin films deposited by RF sputtering were investigated in their dependence on Ar:$O_{2}$ ratio in the deposition plasma. The optical transmission increases with the increase in oxygen concentration, reaching values of 57%, 65% and 67% at 550 nm for O/V ratios of 2.17, 2.63 and 2.76, respectively, in the as-deposited films. The optical band gap determined from absorption data also shows a dependence on the O/V ratio. The films exhibit specific responsivity to monochromatic wavelengths in the UV-Vis-NIR range, with the maximum photo-generated current obtained by excitation with 860 nm wavelength of the films with high O/V ratio.