Electrical and optical properties of highly crystalline W-VO2 nano-films prepared by thermal oxidation of V-WO3 precursors


 Highly-crystalline W doped VO2 (W-VO2) nanofilms were obtained through a thermal oxidation of V-WO3 precursors, with their electric and optical properties being carefully studied. The W-VO2 films contain both rutile and monoclinic phases due to the decrease of phase transition temperature decrease and the ununiform distribution of W ions. It is seen that the W dopants greatly reduces the cool-state resistances and their apparent activation energy, indicating the they form donor levels. The electric analysis also shows that the W-VO2 films have the smooth metal-insulator transitions (MIT) across wide temperature range, with the MIT temperature, temperature coefficient of resistances, and hysteresis width being greatly reduced. The metallic phase contents are estimated from the temperature dependent transmittances, which shows an increase with the W contents at ambient temperatures. Due to the metallic phase and the conductance increase, the IR transmittances and solar modulation of the cool-state W-VO2 films becomes lower.