An infrared investigation of the insulator-to-metal transition in a thin, epitaxially strained VO₂ film

The insulator-to-metal transition temperature of vanadium dioxide (VO₂) can be tuned through epitaxial strain induced by lattice mismatch between a thin VO₂ film and the substrate. Here we report infrared and optical measurements on a very thin (~ 10 nm) VO₂ film on (001) TiO₂ substrate with an insulator-to-metal transition temperature of ~ 305 K, just above room temperature. We map the transition as it evolves in temperature using near-field imaging at a wavelength of ~10μm from a mid-infrared laser. Using our tabletop home-built argon plasma light source, we obtain the broadband near-field infrared spectra on the pristine substrate and the film-substrate system.