Sol-Gel Derived Tungsten Doped VO(2) Thin Films on Si Substrate with Tunable Phase Transition Properties

Vanadium dioxide (VO(2)) with semiconductor-metal phase transition characteristics has presented great application potential in various optoelectrical smart devices. However, the preparation of doped VO(2) film with a lower phase transition threshold on Si substrate needs more investigation for the exploration of silicon-based VO(2) devices. In this work, the VO(2) films doped with different contents of W element were fabricated on high-purity Si substrate, assisted with a post-annealing process. The films exhibited good crystallinity and uniform thickness. The X-ray diffraction and X-ray photoelectron spectroscopy characterizations illustrated that W element can be doped into the lattice of VO(2) and lead to small lattice distortion. In turn, the in situ FT-IR measurements indicated that the phase transition temperature of the VO(2) films can be decreased continuously with W doping content. Simultaneously, the doping would lead to largely enhanced conductivity in the film, which results in reduced optical transmittance. This work provides significant insights into the design of doped VO(2) films for silicon-based devices.