Vanadium oxide (VO 2) is a narrow band gap material (Eg 0.7 eV) with a thermally induced insulator-metal phase transition at ∼343 K and evidence of an electric field induced transition at T 343 K. To explore the electronic properties of VO 2, a sandwich structure was prepared with a 2 nm VO 2 layer embedded between an oxidized Si(100) surface and a 2 nm hafnium oxide (HfO 2) layer. The layer structure was confirmed with high resolution transmission electron microscopy. The electronic properties were characterized with x-ray and ultraviolet photoemission spectroscopy, and the band alignment was deduced on both n-type and p-type Si substrates. The valence band offset between VO 2 and SiO 2 is measured to be 4.0 eV. The valence band offset between HfO 2 and VO 2 is measured to be ∼3.4 eV. The band relation developed from these results demonstrates the potential for charge storage and switching for the embedded VO 2 layer.
ASJC Scopus subject areas
- Physics and Astronomy(all)