Low-temperature deposition of VO2 films with high crystalline degree by embedding multilayered structure

- Magnetron sputtering of VO2 was realized at 300 °C without annealing.
- VO2/TiO2/ZnO/Substrate displays better optical performance for smart window.
- Epitaxial relationship is VO2(M)(010)[100]//TiO2 (100)[001]//ZnO(001)[100], [010], [-1-10].

It is a long-standing challenge in the fabrication of single-phase VO2 films at low temperature on Si substrate or glass substrate due to their thermodynamic phase-instability and the polymorphic structures. Recently, the demand for high-quality thin films deposited at low temperature is strongly pushed by their applications on devices and smart windows. Thermochromic films of VO2, as well as multilayer films of VO2/ZnO and VO2/TiO2/ZnO, were made by magnetron sputtering method and characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), UV-visible-NIR spectrophotometer, (scanning) transmission electron microscopy ((S)TEM) and Electron energy loss spectroscopy (EELS). Films with high crystalline degree VO2 single crystal phase were obtained at a fairly low temperature of 300 °C without subsequent annealing by embedding ZnO and TiO2 layers between VO2 and substrates. It is demonstrated that VO2/TiO2/ZnO films could display higher luminous transmittance and better semiconductor to metal transition (SMT) performance. Our data can serve a promising point for industrial production with high degree of crystallinity at a low temperature.