Low-temperature growth of high-quality VO2 epitaxial film on c-plane sapphire by reactive magnetron sputtering

The growth of VO2 epitaxial films has been researched extensively for obtaining excellent phase-transition performance. However, previous methods typically necessitate high temperatures or post-annealing processes, which elevate both experimental complexity and cost. In this work, we prepared high-quality VO2 epitaxial films by reactive magnetron sputtering directly under a low growth temperature. Benefiting from the determination of the oxygen pressure ratio from the theoretical analysis of the sputtering process model, single-stoichiometric VO2 epitaxial films could be prepared under 450 °C with a resistance change of 103, and above 500 °C with a resistance change exceeding 104. The mechanism of achieving low-temperature growth of VO2 epitaxial films was analyzed utilizing Thornton's zone model; finally, the epitaxial characteristics of VO2 on the sapphire substrate were confirmed from in-plane and out-of-plane directions. This work presents a guideline for the low-temperature growth of VO2 epitaxial films with enhanced phase-transition performance, thereby reducing both the cost and the requirements associated with the epitaxial growth of VO2 films.