Sharp contrast in the electrical and optical properties of vanadium Wadsley (VmO2m+1,m>1) epitaxial films selectively stabilized on (111)-oriented Y-stabilized ZrO2

Songhee Choi, Jaeseok Son, Junhyeob Oh, Ji-Hyun Lee, Jae Hyuck Jang, and Shinbuhm Lee
Phys. Rev. Materials 3, 063401 – Published 4 June 2019
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Abstract

Four oxidation states (V2+,V3+,V4+,andV5+) in vanadium oxides and the conversion between them have attracted attention for application to batteries and electronics. Compared to single-valence counterparts, however, there have been few reports on the fundamental properties of mixed-valence vanadium oxide films, as their complexity and closeness in thermodynamic phase diagrams hinder the formation of pure phases in film. Here, using an epitaxial growth technique with precise control of oxygen partial pressure (20–100 mTorr) on (111)-oriented Y-stabilized ZrO2, we selectively stabilize pure phases of VO2(B) (m=), V6O13 (m=6), and V2O5 (m=2), so-called Wadsley phases (VmO2m+1,m>1) in which V4+ and/or V5+ can coexist. Fractional increase of V4+ changes the electrical ground state, insulating VO2(B) and V2O5, metallic V6O13 transition into insulators below 150 K. While VO2(B) and V6O13 exhibit strong spectral weights at low photon energy in the room-temperature extinction coefficients, the band-edge absorption shifts toward higher photon energy for smaller m, opening an indirect band gap of 2.6 eV in V2O5. The sharp contrast of electrical and optical properties between vanadium Wadsley phases highlights the importance of precisely controlling the oxidation state of vanadium.

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  • Received 25 November 2018
  • Revised 11 February 2019

DOI:https://doi.org/10.1103/PhysRevMaterials.3.063401

©2019 American Physical Society

Physics Subject Headings (PhySH)

  1. Research Areas
  1. Physical Systems
  1. Techniques
Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Songhee Choi1, Jaeseok Son2, Junhyeob Oh3, Ji-Hyun Lee3, Jae Hyuck Jang3, and Shinbuhm Lee1,*

  • 1Department of Emerging Materials Science, Daegu-Gyeongbuk Institute of Science and Technology, Daegu 42988, Republic of Korea
  • 2Center for Correlated Electron Systems, Institute for Basic Science and Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea
  • 3Electron Microscopy Research Center, Korea Basic Science Institute, Daejeon 34133, Republic of Korea

  • *lee.shinbuhm@dgist.ac.kr

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Vol. 3, Iss. 6 — June 2019

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