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Journal of Nanomaterials
Volume 2014 (2014), Article ID 183954, 6 pages
http://dx.doi.org/10.1155/2014/183954
Research Article

Room Temperature Optical Constants and Band Gap Evolution of Phase Pure M1-VO2 Thin Films Deposited at Different Oxygen Partial Pressures by Reactive Magnetron Sputtering

1State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics (SIC), Chinese Academy of Sciences (CAS), Dingxi 1295, Changning, Shanghai 200050, China
2Graduate University of Chinese Academy of Sciences, Yuquanlu 19, Beijing 100049, China
3School of Materials Science and Engineering, Shanghai University, 99 Shangda, Shanghai 200444, China

Received 13 October 2013; Accepted 11 December 2013; Published 2 January 2014

Academic Editor: Yoshitake Masuda

Copyright © 2014 Meng Jiang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Spectroscopic ellipsometry study was employed for phase pure VO2(M1) thin films grown at different oxygen partial pressures by reactive magnetron sputtering. The optical constants of the VO2(M1) thin films have been determined in a photon energy range between 0.73 and 5.05 eV. The near-infrared extinction coefficient and optical conductivity of VO2(M1) thin films rapidly increase with decreasing O2-Ar ratios. Moreover, two electronic transitions can be uniquely assigned. The energy gaps correlated with absorption edge at varied O2-Ar ratios are almost the same (~2.0 eV); consequently, the absorption edge is not significantly changed. However, the optical band gap corresponding to semiconductor-to-metal phase transition decreases from 0.53 to 0.18 eV with decreasing O2-Ar ratios.