Thermally Induced Switching of Electrical and Optical Characteristics of VO₂ Thin Nanostructured Films Fabricated by Radio Frequency Magnetron Sputtering

Thin films of VO₂ were deposited using magnetron sputtering, and abrupt switching of the optical and electrical characteristics due to phase transformation was studied. At a temperature of 58 °C, the as-prepared VO₂ films transformed from the insulator to a metallic phase, at a temperature lower than the values reported in the literature. This transformation corresponds to the switching from monoclinic to rutile tetragonal phase, where the electron number density is suddenly increased as a result of V–V dimer dissociation, and this phase transformation is found to be absent in annealed VO₂ films. Above 58 °C, the optical absorption of as-prepared VO₂ films in the metallic phase was found to be quite anomalous in infrared region due to plasmonic resonance. This phase transformation is reflected in the FTIR spectrum as relative dominance of the vibrational modes. Also, the structural and morphological characterizations of the fabricated VO₂ thin films were investigated.