Phase and structural characterization of vanadium oxide films grown on amorphous SiO2/Si substrates

Abstract

The VO2 multiphases such as V2O5, VO2, and V2O3 are confirmed and the correlations between structural characteristics and growth conditions was investigated using the scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS). Also, the electrical characteristics of VO2-based three terminal devices, attributed to structural and phase changes, are discussed. The spectra of VO2 have three peaks composed of VO2 at binding energy (BE)=516.2 eV, V2O3 at BE=515.6 eV, and V2O5 at BE=517.0 eV. With increase in the growth temperature, crystal quality of VO2 films improves and approaches single phase of VO2, then the peak position shifts to the spectra of oxygen-poor phase (V2O3). With increase in the O2 flow, the peak position shifts to the spectra of oxygen-rich phase (V2O5). VO2 films grown at optimal growth conditions have a change in resistivity of the order of 102 near a critical temperature, Tc=340 K.