Substrate bias effect on the fabrication of thermochromic VO2 films by reactive RF sputtering

Vanadium oxide VOx films were deposited by reactive RF magnetron sputtering by applying a substrate bias, in which the Ar ions in plasma impacted the growing film surface. The vanadium valence of the VOx film decreased when the substrate negative bias voltage was increased. The VO2 film was successfully deposited at a substrate temperature of 400 degrees C and with a bias voltage of -50 to -80 V. The transition temperatures of the VO2 films with a substrate bias of -50 and -80 V were about 56 degrees C and 44 degrees C, respectively.