Sapphire substrate-induced effects in VO_2 thin films grown by oxygen plasma-assisted pulsed laser deposition

摘要

We investigate the structural and electronic properties of VO_2 thin films on c-plane sapphire substrates with three different surface morphologies to control the strain at the substrate-film interface. Only non-annealed substrates with no discernible surface features (terraces) provided a suitable template for VO_2 film growth with a semiconductor-metal transition (SMT), which was much lower than the bulk transition temperature. In addition to strain, oxygen vacancy concentration also affects the properties of VO_2, which can be controlled through deposition conditions. Oxygen plasma-assisted pulsed laser deposition allows favorable conditions for VO_2 film growth with SMTs that can be easily tailored for device applications.