Band alignment of InGaZnO 4/Si interface by hard x-ray photoelectron spectroscopy

Kyeongmi Lee, Kenji Nomura, Hiroshi Yanagi, Toshio Kamiya, Eiji Ikenaga, Takeharu Sugiyama, Keisuke Kobayashi, Hideo Hosono

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Abstract

Although amorphous InGaZnO 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 (χ) and the ionization potentials (I p) of crystalline and amorphous InGaZnO 4 (c-IGZO and a-IGZO) were measured using bulk-sensitive hard x-ray photoelectron spectroscopy. First, the χ and I p values of c-IGZO and a-IGZO thin films were estimated by aligning the Zn 2p 3/2 core level energies to a literature value for ZnO, which provided χ 3.90 eV and I 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 ∼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.

Original languageEnglish
Article number033713
JournalJournal of Applied Physics
Volume112
Issue number3
DOIs
Publication statusPublished - Aug 1 2012
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

Cite this

Lee, K., Nomura, K., Yanagi, H., Kamiya, T., Ikenaga, E., Sugiyama, T., ... Hosono, H. (2012). Band alignment of InGaZnO 4/Si interface by hard x-ray photoelectron spectroscopy. Journal of Applied Physics, 112(3), [033713]. https://doi.org/10.1063/1.4744983