External strain dependent optical studies of VO2 thin films
Hsiao-Wen Chen1*, C. I. Li (李建毅)2, C. H. Ma (馬俊皓)2, Y. H. Chu (朱英豪)2, H. L. Liu(劉祥麟)1
1Department of Physics,, National Taiwan Normal University, Taipei, Taiwan
2Department of Materials Science Engineering, National Chiao Tung University, Hsinchu, Taiwan
* Presenter:Hsiao-Wen Chen, email:josephmdtw@gmail.com
We present the stain dependent Raman scattering and optical transmittance measurements of VO2 thin films. The VO2 thin films were grown on muscovite substrate by using pulsed laser deposition and molecular-beam epitaxy. By applying an external compressive strain, the observed Bg and Ag symmetry Raman phonon modes at approximately 438 and 616 cm-1 exhibit a buleshift. Upon passing through the metal-insulator transition (MIT) temperature at about 62 °C, the tensile strain optical transmittance spectra show the MIT temperature shifts to higher temperature. By contrast, the compressive strain dependent optical transmittance spectra show the MIT temperature shifts to lower temperature. The ratio of MIT temperature shift to stain is 3.7 °C/%. This phenomenon was associated with the external strain obstructs the structural phase transition of VO2 thin films.

Keywords: VO2, raman spectra, strain, transmittance spectra