Control of metal-insulator transition temperature in VO2 thin films grown on RuO2/TiO2 templates by strain modification

Ruthenium dioxide (RuO2) is an ideal buffer layer for vanadium dioxide (VO2) heterostructures due to its high electrical conductivity and matching crystal structure with metallic VO2. VO2 thin films were deposited on single crystal TiO2 (001) substrates with RuO2 buffer layers via pulsed laser deposition. The metal-insulator transition temperature (TMIT) in VO2 films can be controlled by the epitaxial strain between the VO2 film and RuO2 buffer layer by adjusting the buffer layer thickness (10 - 50 nm). We observed a decrease in the TMIT of VO2 films from 59 °C to 24 °C as the RuO2 thickness decreased from 50 nm to 10 nm. Additionally, we show that the RuO2 buffer layer can sustain an intermediate strain state in VO2 films up to 100 nm in thickness with a subsequently lower TMIT (30 °C). The 10 nm thick RuO2 buffer layer can reduce the TMIT in VO2 films by providing a pathway to relieve the strain through grain boundaries.