Physical properties and phase transition observed in vanadium oxide thin films deposited by RF magnetron sputtering

Abstract

In this work, we focus on the study of structural and electrical properties of vanadium oxide thin films synthesized by RF magnetron sputtering. The samples were deposited on glass at 0%, 5%, 10% and 20%, O2 concentration inside the vacuum of the chamber. The films were characterized by x-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), Conventional and High Resolution Transmission Electron Microscopy (CTEM and HRTEM, respectively), UV–vis Spectroscopy and Cyclic Voltammetry (CV). The increase in oxygen concentration induces agglomeration behaviour atmospheric-deposition-dependent on film characteristic surface, this phenomenon in turn, influences its structural and electrical properties. A reducing atmosphere enabled the formation of V2O5 to VO2 phases, respectively, the mixed-valence of V5+ and V4+ related with V2O5 and VO2 system were established. The existence of V2O5 and VO2 on the surface film is supported by x-ray photoelectron spectroscopy analysis. The reduction process in substrate surface was detected from 10%, content of O2 which showed a local minimum associated with agglomeration of V-oxide in the surface substrate, and a possible heterostructure configuration. The electrochemical response showed a minimum in diffusion cathodic associated to kinetic phenomena of double layer. However, the diffusion anodic was constant, associated to rapid electronic transfer and maximum coloration efficiency during electrochromic experiment. The co-existence phases on the surface films generates electrochromic and thermochromic behaviour.