The electrical properties of WO3 thin films vary significantly depending on the growth conditions. In this work, the influence of O2 gas on the band gap of WO3 thin films during growth was investigated via electronic structure characterization using X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and X-ray emission spectroscopy (XES). A substantial decrease in the electrical conductivity of the WO3 films was observed with an increase in the O2 partial pressure during growth. Spectral differences in the peak energy and intensity were apparent for WO3 films grown under only Ar and those grown in Ar:O2. It is difficult to explain the acquired spectrum of WO3 with oxygen defects through the rigid-band model in terms of the simple addition of electrons to the conduction band of WO3. Our results show that an oxygen deficiency in WO3 moves the conduction band to the Fermi edge.
Bibliographical noteFunding Information:
This work was supported by a research project of the National Research Foundation of Korea (Grant No. 2017R1D1A3B03034867 ) and the Yonsei University Future-leading Research Initiative (Grant No. 2017-52-0071 ). Part of this study was carried out at the Stanford Synchrotron Radiation Lightsource, a National User Facility operated by Stanford University on behalf of the Basic Energy Sciences, U.S. Department of Energy.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Physics and Astronomy(all)