Hydrogen-doping stabilized metallic VO2 (R) thin films and their application to suppress Fabry-Perot resonances in the terahertz regime

We demonstrate that catalyst-assisted hydrogen spillover doping of VO2 thin films significantly alters the metal-insulator transition characteristics and stabilizes the metallic rutile phase at room temperature. With hydrogen inserted into the VO2 lattice, high resolution X-ray diffraction reveals expansion of the V-V chain separation when compared to the VO2(R) phase. The donated free electrons, possibly from O-H bond formation, stabilize the VO2(R) to low temperatures. By controlling the amount of dopants to obtain mixed insulating and metallic phases, VO2 resistivity can be continuously tuned until a critical condition is achieved that suppresses Fabry-Perot resonances. Our results demonstrate that hydrogen spillover is an effective technique to tune the electrical and optical properties of VO2 thin films.