Improved crystallinity, carrier mobility and transparency of SrVO₃ films by low-temperature post-annealing in air

Perovskite-type SrVO₃ is a promising candidate for indium-free transparent conducting oxides. High carrier conductivity and transparency are key factors for high-performance transparent conducting oxides. In this study, we report a simple method to improve the crystallinity, carrier mobility, and transparency of SrVO₃ films: low-temperature post-annealing in air. Post-annealing at 150-250 °C for 24 h in air was conducted for SrVO₃ films grown on LaAlO₃ substrates. As a result, post-annealing at 150-200 °C improved the in-plane crystallinity, leading to the formation of epitaxial SrVO₃ films. Shrinkage of the lattice of the films and X-ray photoemission spectroscopy results suggested partial oxidation of V⁴⁺ to V⁵⁺ during the post-annealing. In addition, the carrier mobility and transparency of the films improved, although the resistivity increased due to the reduced carrier density. Post-annealing at 200 °C increased the figure of merit for transparent conductors. Our findings demonstrate that low-temperature post-annealing is an effective method to improve the crystallinity, carrier mobility, and transparency of SrVO₃ and similar compounds.