Electrical Properties and Structure of p-Type Amorphous Oxide Semiconductor xZnO·Rh2O3

Authors

  • T. Kamiya,

    1. Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
    2. Second address: ERATO-SORST, JST, in Frontier Collaborative Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
    Search for more papers by this author
  • S. Narushima,

    1. Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
    Search for more papers by this author
  • H. Mizoguchi,

    1. Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
    Search for more papers by this author
  • K. Shimizu,

    1. Department of Economics, Keio University, 4-1-1 Hiyoshi, Minato-Kita-ku, Yokohama 223-8521, Japan
    Search for more papers by this author
  • K. Ueda,

    1. ERATO-SORST, JST, in Frontier Collaborative Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
    2. Second address: Kyushu Institute of Technology, 1–1 Sensui-cho, Tobata-ku, Kitakyushu, Fukuoka 804-8550, Japan.
    Search for more papers by this author
  • H. Ohta,

    1. ERATO-SORST, JST, in Frontier Collaborative Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
    2. Second address: Nagoya University, Furo-cho, Chigusa-ku, Nagoya, 464-8603, Japan.
    Search for more papers by this author
  • M. Hirano,

    1. Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
    2. Second address: ERATO-SORST, JST, in Frontier Collaborative Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
    3. Second address: Frontier Collaborative Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
    Search for more papers by this author
  • H. Hosono

    1. Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
    2. Second address: ERATO-SORST, JST, in Frontier Collaborative Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
    3. Second address: Frontier Collaborative Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
    Search for more papers by this author

Abstract

p-Type conduction in amorphous oxide was firstly found in zinc rhodium oxide (ZnO·Rh2O3) (Adv. Mater.2003, 15, 1409), and it is still the only p-type amorphous oxide to date. It was reported that an ordered structure at the nanometer scale was contained and its electronic structure is not clear yet. In this paper, optoelectronic and structural properties are reported in detail for xZnO·Rh2O3 thin films (x = 0.5–2.0) in relation to the chemical composition x. All the films exhibit positive Seebeck coefficients, confirming p-type conduction. Local network structure strongly depends on the chemical composition. Transmission electron microscopic observations reveal that lattice-like structures made of edge-sharing RhO6 network exist in 2–3 nm sized grains for rhodium-rich films (x= 0.5 and 1.0), while the zinc-rich film (x= 2) is completely amorphous. This result indicates that excess Zn assists to form an amorphous network in the ZnO–Rh2O3 system since Zn ions tend to form corner-sharing networks. The electronic structure of an all-amorphous oxide p-ZnO·Rh2O3/n-InGaZnO4 junction is discussed with reference to electrical characteristics and results of photoelectron emission measurements, suggesting that the p/n junction has large band offsets at the conduction and valence bands, respectively.

Ancillary