Correlation Between High Gas Sensitivity and Dopant Structure in W-doped ZnO

Shun Fukami, Munetaka Taguchi, Yutaka Adachi, Isao Sakaguchi, Ken Watanabe, Toyohiko Kinoshita, Takayuki Muro, Tomohiro Matsushita, Fumihiko Matsui, Hiroshi Daimon, and Taku T. Suzuki
Phys. Rev. Applied 7, 064029 – Published 28 June 2017

Abstract

W-doped ZnO films are synthesized by pulsed laser deposition on Al2O3(112¯0) substrate, and their gas-sensing properties are investigated. Significantly improved sensitivity and response time to ethanol vapor are achieved. In order to study the relation between high sensing performance and local structure around the dopant W site, we carry out two-dimensional photoelectron diffraction on W-doped ZnO thin films at two different annealing temperatures (600 and 1000°C). The photoelectron-intensity angular-distribution (PIAD) patterns of Zn 3p and W 4f core levels show the presence of forward-focusing peaks of very different relative intensities in the bulk and surface. From the PIAD patterns and their circular dichroism, we find clear evidence for the substitution of a segregated W atom into a Zn site in the second atomic layer. The result shows a direct relationship between the drastic increase in gas-sensing performance via W doping and the segregation of W at the surface. It also demonstrates that this photoelectron-diffraction measurement is a powerful tool for the study of the local structure of dopant sites in gas-sensing materials.

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  • Received 27 December 2016

DOI:https://doi.org/10.1103/PhysRevApplied.7.064029

© 2017 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Shun Fukami1, Munetaka Taguchi1,*, Yutaka Adachi2,†, Isao Sakaguchi2, Ken Watanabe3, Toyohiko Kinoshita4, Takayuki Muro4, Tomohiro Matsushita4, Fumihiko Matsui1, Hiroshi Daimon1, and Taku T. Suzuki2

  • 1Material Science, Nara Institute of Science and Technology (NAIST), Ikoma, Nara 630-0192, Japan
  • 2National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0044, Japan
  • 3Faculty of Engineering Science, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580, Japan
  • 4Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan

  • *Corresponding author. mtaguchi@ms.naist.jp
  • Corresponding author. ADACHI.Yutaka@nims.go.jp

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Vol. 7, Iss. 6 — June 2017

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