Structural and electrical properties of V₂O₃ thin films on c-plane Al₂O₃ fabricated by reactive-HiPIMS and dcMS techniques

The study presents the synthesis of epitaxial V2O3 thin films on c-plane Al2O3 substrates by reactive high-power impulse (HiPIMS) and direct current (dcMS) magnetron sputtering. The results reveal that for fixed deposition conditions and discharge power, well defined epitaxial layers can be attained using both HiPIMS and dcMS. For dcMS we observe the formation of these epitaxial films down to flow rate values of 1.3 sccm while for HiPIMS we observe an extended operation window down to much lower oxygen flow of 0.5 sccm without sacrificing the structural quality of the films. Furthermore, the effect of varying HiPIMS discharge parameters i.e. repetition frequency and average power for fixed O2 flow setting, were explored in order to determine their effect on the structural quality and electrical characteristics of the films. The magnitude of the metal–insulator transition (MIT) and the transition temperature is correlated to the film stoichiometry which can be fine-tuned by mapping the HiPIMS discharge parameters, displaying a total change in resistance of ∼7 decades over the studied temperature range. The MIT temperature and magnitude obtained for films fabricated by HiPIMS, even for low O2 flow settings (down to 0.6–0.5 sccm), displayed superior characteristics compared to films fabricated by dcMS where a minimum O2 flow of 1.3 sccm was needed.