Band alignment of InGaZnO{sub 4}/Si interface by hard x-ray photoelectron spectroscopy
- Materials and Structures Laboratory, Tokyo Institute of Technology, Mailbox R3-1, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan)
- Frontier Research Center, Tokyo Institute of Technology, Mailbox S2-13, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan)
- Interdisciplinary Graduate School of Medical and Engineering Material Science and Technology, University of Yamanashi, 4-4-37 Takeda, Kofu, Yamanashi 400-8510 (Japan)
- Japan Synchrotron Radiation Research Institute, SPring-8, Hyogo 679-5198 (Japan)
- National Institute for Materials Science, SPring-8, Hyogo 679-5148 (Japan)
Although amorphous InGaZnO{sub 4} has intensively been studied for a semiconductor channel material of thin-film transistors in next-generation flat-panel displays, its electronic structure parameters have not been reported. In this work, the electron affinities ({chi}) and the ionization potentials (I{sub p}) of crystalline and amorphous InGaZnO{sub 4} (c-IGZO and a-IGZO) were measured using bulk-sensitive hard x-ray photoelectron spectroscopy. First, the {chi} and I{sub p} values of c-IGZO and a-IGZO thin films were estimated by aligning the Zn 2p{sub 3/2} core level energies to a literature value for ZnO, which provided {chi} = 3.90 eV and I{sub p} = 7.58 eV for c-IGZO and 4.31 eV and 7.41 eV for a-IGZO. It was also confirmed that the escape depth of the photoelectrons excited by the photon energy of 5950.2 eV is 3.3 nm for a-IGZO and large enough for directly measuring the interface electronic structure using a-IGZO/c-Si heterojunctions. It provided the valence band offset of {approx}2.3 eV, which agrees well with the above data. The present results substantiate that the a-IGZO/c-Si interface follows well the Schottky-Mott rule.
- OSTI ID:
- 22089378
- Journal Information:
- Journal of Applied Physics, Vol. 112, Issue 3; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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