Tuning the metal insulator transition of vanadium dioxide on oxide nanosheets

For practical applications, tuning the metal-insulator transition (MIT) behavior of high-quality vanadium dioxide (VO2) on arbitrary substrates, such as Si and glass, is desirable. Here, we demonstrate the ability to tune the MIT temperature (TMIT) of VO2 films by growing them on NbWO6 (NWO) nanosheets on arbitrary substrates and varying the film thicknesses. The oxidation and crystal structure of VO2 films are determined by x-ray photoelectron spectroscopy and temperature-dependent x-ray diffraction, respectively. It is observed that as the film thickness increases, the TMIT also increases to the bulk value, 341 K, because of the increase in the rutile c-axis of VO2. The strain effect accompanying with the film thickness variation on NWO nanosheets contribute to the shortening of the rutile cR axis in thin films and, hence, the lowering of TMIT of VO2. Furthermore, the arbitrary underlying substrates have negligible influence on the MIT behavior of VO2 on NWO nanosheets. These results open up the possibility to more freely choose a technical substrate material for functional VO2 films and tune its MIT.