title: Determination of the surface band bending in InxGa1-xN films by hard x-ray photoemission spectroscopy.
abstract: Core-level and valence band spectra of InxGa1-xN films were measured using hard x-ray photoemission spectroscopy (HX-PES). Fine structure, caused by the coupling of the localized Ga 3d and In 4d with N 2s states, was experimentally observed in the films. Because of the large detection depth of HX-PES (∼20 nm), the spectra contain both surface and bulk information due to the surface band bending. The InxGa1-xN films (x= 0-0.21) exhibited upward surface band bending, and the valence band maximum was shifted to lower binding energy when the mole fraction of InN was increased. On the other hand, downward surface band bending was confirmed for an InN film with low carrier density despite its n-type conduction. Although the Fermi level (EF) near the surface of the InN film was detected inside the conduction band as reported previously, it can be concluded thatEFin the bulk of the film must be located in the band gap below the conduction band minimum.
authors.affiliation: Photonic Materials Unit, National Institute for Materials Science, Tsukuba 305-0044, Japan; Doctoral Program in Materials Science and Engineering, Tsukuba University, Tsukuba 305-8573, Japan.
authors.forename: Mickael
authors.initials: M
authors.lastname: Lozac'h
authors.affiliation: Synchrotron X-ray Station at SPring-8, National Institute for Materials Science, Hyogo 679-5148, Japan.
authors.forename: Shigenori
authors.initials: S
authors.lastname: Ueda
authors.affiliation: State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, People's Republic of China.
authors.forename: Shitao
authors.initials: S
authors.lastname: Liu
authors.affiliation: Synchrotron X-ray Station at SPring-8, National Institute for Materials Science, Hyogo 679-5148, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Yoshikawa
authors.affiliation: Wide Bandgap Material Group, National Institute for Materials Science, Tsukuba 305-0044, Japan; ICYS-MANA, National Institute for Materials Science, Tsukuba 305-0044, Japan.
authors.forename: Sang
authors.initials: S
authors.lastname: Liwen
authors.affiliation: State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, People's Republic of China.
authors.forename: Xinqiang
authors.initials: X
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, People's Republic of China.
authors.forename: Bo
authors.initials: B
authors.lastname: Shen
authors.affiliation: Photonic Materials Unit, National Institute for Materials Science, Tsukuba 305-0044, Japan; Doctoral Program in Materials Science and Engineering, Tsukuba University, Tsukuba 305-8573, Japan.
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Sakoda
authors.affiliation: Synchrotron X-ray Station at SPring-8, National Institute for Materials Science, Hyogo 679-5148, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Kobayashi
authors.affiliation: Wide Bandgap Material Group, National Institute for Materials Science, Tsukuba 305-0044, Japan; JST-ALCA, The Japan Science and Technology Agency, Tokyo 102-0076, Japan.
authors.forename: Masatomo
authors.initials: M
authors.lastname: Sumiya
keywords: 10.06; 10.11; 20.11; GaN; HX-PES; InGaN; InN; band bending; core level; hard x-ray photoemission spectroscopy; hybridization; valence band maximum