Effect of Radio-Frequency Power on the Composition of BiVO4 Thin-Film Photoanodes Sputtered from a Single Target

BiVO4 films were fabricated by radio frequency (RF) sputtering from a single target. The deposited BiVO4 films were found to be rich in Bi, and the reason for the Bi-richness was investigated. It was inferred from the Monte Carlo simulation that, during sputtering, the transfer process of target atoms through argon gas played a major role in this phenomenon. The transfer process resulted in an imbalanced ratio of Bi and V, arising from the difference in atom mass and interaction radius. The high RF power was found to be effective in adjusting the Bi/V ratio, influencing the sputtering yield. This type of preferential sputtering was maintained by the diffusion of target atoms from the bulk to the surface. BiVO4 films with monoclinic scheelite crystal structures were obtained at high RF power values and found to exhibit photocatalytic performances beneficial for photoanodic applications.