Thickness-dependent metal-to-insulator transition in epitaxial VO sub(2) films

• Published in: Materials research express Vol. 1; no. 4; pp. 1 - 8
• Main Authors: Zhi, Bowen, Gao, Guanyin, Tan, Xuelian, Chen, Pingfan, Wang, Lingfei, Jin, Shaowei, Wu, Wenbin
• Format: Journal Article
• Language: English
• Published: 01.12.2014
• Subjects: Annealing; Dimerization; Film thickness; Solvents; Thick films; Titanium; Titanium dioxide; Vanadium oxides
• ISSN: 2053-1591; 2053-1591
• DOI: 10.1088/2053-1591/1/4/046402

The metal-to-insulator transition (MIT) of VO sub(2) films with a thickness of 3-100 nm on TiO sub(2)(001) substrates has been investigated. When varying the film thickness from 10 to 100 nm, the MIT temperature was first kept at 290 K in the range of 10-14 nm, and then increased with thickness increasing due to the strain relaxation. The origin of the suppressed transition in VO sub(2) films thinner than 6nm was also investigated. When prolonging the in situ annealing time, the sharpness, amplitude and width of the transition for 4nm thick films were all increased, suggesting improved crystallinity rather than Ti diffusion from the substrates. In addition, the MIT was suppressed when the VO sub(2) films were covered by a TiO sub(2) layer, indicating that the interface effect via the confinement of the dimerization of the V atoms should be the main reason.