Controlling the crystalline orientation and textual morphologies of the VO2 film and the effect on insulator-metal transition properties

Monoclinic VO2 films were prepared over quartz substrates through thermal oxidation of sputtered vanadium films under continuous O-2 flow in a vacuum. It was found that an additional vacuum pre-heating before the thermal oxidation could have a great effect on film crystalline orientation and textual morphologies. The film exhibits a preferable growth along [011] direction and consists of uniform small inter-connected nanoparticles, while the untreated film shows (200) orientation and is composed of large irregular nanoparticles that connect via disorder boundaries. The (011) orientated film shows slightly higher full solar and IR light modulations. The electric resistance results also show that the metal-insulator transition (MIT) of the (011) orientated film presents a larger amplitude, higher sharpness, and narrower hysteresis as compared to the (200) orientated film. The difference in textual structures of the orientated films is the main physical reason that affects the MIT of m-VO2 films.

Automated summary

In this study, monoclinic VO2 films were prepared on quartz substrates through thermal oxidation with a vacuum pre-heating step. It was found that the pre-heating step significantly influenced the crystalline orientation and textual morphologies of the films. The orientated film demonstrated better growth direction, uniform nanoparticles, higher light modulations, and sharper electric resistance transitions compared to the untreated film. These differences were attributed to the structural variations of the orientated films.