Reactive pulsed DC magnetron sputtering deposition of vanadium oxide thin films: Role of pulse frequency on the film growth and properties

Abstract

In this study, vanadium oxide (VOx) thin films were prepared by reactive pulsed DC magnetron sputtering (PDMS). The influence of pulse frequency (Fp) on the deposition process and properties of VOx films was investigated. The obtained results indicate that with the increase of Fp, which not only can enhance the oxidation of vanadium but also can facilitate the formation of a denser microstructure and smoother surface morphology in the films. More importantly, films with composition from metal-rich to maximum stoichiometry can be accessed by tuning the Fp, without varying any other parameters, especially, the flow rate of reactive gas. And temperature dependent electrical properties of the VOx films can also be tailored via the Fp to fall in the desirable range for microbolometer applications. The impacts of Fp on the reaction between V and O, thin film growth and some dynamic processes occurring during reactive PDMS were analyzed. The corresponding underlying mechanisms were discussed in detail. Our present work may provide a practical and effective way to develop the reactive sputtering towards hysteresis-free, and also paves the way for optimizing the reactive sputtered VOx films with desirable properties via Fp.