Electronic structure of W-doped VO2 thin films with giant metal-insulator transition investigated by hard x-ray core-level photoemission spectroscopy

We use bulk-sensitive hard X-ray core-level photoemission spectroscopy to investigate the electronic structure of 1 at. % W-doped VO2 (VWO) thin films exhibiting a high temperature coefficient of resistance, above -10%/K at room temperature. According to the W 4d core-level spectra, the chemical state of doped W takes only a 6+ valence state, which suggests the introduction of V3+. The satellite structure of the V 2p3/2 main peak, which corresponds to the metallic-coherent screened states, was enhanced for VWO compared with VO2 indicating that electron doping plays an important role in the control of metal-insulator transition. (author)