Revealing the role of oxygen vacancies on the phase transition of VO2 film from the optical-constant measurements

Lele Fan; Xiangqi Wang; Feng Wang; Qinfang Zhang; Lei Zhu; Qiangqiang Meng; Baolin Wang; Zengming Zhang; Chongwen Zou

doi:10.1039/c8ra03292k

Revealing the role of oxygen vacancies on the phase transition of VO₂ film from the optical-constant measurements

RSC Adv. 2018 May 24;8(34):19151-19156. doi: 10.1039/c8ra03292k. eCollection 2018 May 22.

Authors

Lele Fan^{1

2}, Xiangqi Wang³, Feng Wang¹, Qinfang Zhang¹, Lei Zhu¹, Qiangqiang Meng¹, Baolin Wang⁴, Zengming Zhang³, Chongwen Zou²

Affiliations

¹ Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province, Yancheng Institute of Technology Yancheng 224051 P. R. China qfangzhang@gmail.com.
² National Synchrotron Radiation Laboratory, University of Science and Technology of China Hefei 230029 P. R. China czou@ustc.edu.cn.
³ Department of Physics, University of Science and Technology of China Hefei 230026 P. R. China.
⁴ School of Physical Science and Technology, Nanjing Normal University Nanjing 210023 P. R. China.

Abstract

Vanadium dioxide (VO₂) material shows a distinct metal-insulator transition (MIT) at the critical temperature of ∼340 K. Similar to other correlated oxides, the MIT properties of VO₂ is always sensitive to those crystal defects such as oxygen vacancies. In this study, we investigated the oxygen vacancies related phase transition behavior of VO₂ crystal film and systematically examined the effect of oxygen vacancies from the optical constant measurements. The results indicated that the oxygen vacancies changed not only the electron occupancy on V 3d-O 2p hybrid-orbitals, but also the electron-electron correlation energy and the related band gap, which modulated the MIT behavior and decreased the critical temperature resultantly. Our work not only provided a facile way to modulate the MIT behavior of VO₂ crystal film, but also revealed the effects of the oxygen vacancies on the electronic inter-band transitions as well as the electronic correlations in driving this MIT process.