Characteristics of W- and Ti-doped VO(2) thin films prepared by sol-gel method

W- and Ti-doped VO(2) thin films were deposited onto sapphire by the sol-gel method. Both films were grown with (020)-preferred direction. Doping of W had a great effect on the transition behaviors. A 1.2 atom % W-doped VO(2) film showed a largely reduced resistance in the insulator state and decreased the transition temperature to 313 K. However, Ti-doped VO(2) film had a little change of the transition temperature, and it was 350 K, even for the 20 atom % Ti doping. The resistance in the metal state was very large, which means a markedly small change of the resistance at the transition temperature. Further study is required for understanding the effects of doping VO(2) film with metal ions.