Fabrication and Raman scattering study of epitaxial VO_2 films on MgF_2 (001) substrates

摘要

Effects of epitaxial strain on metal-insulator transitions (MITs) of epitaxial VO_2 films grown on MgF_2 (001) substrates were examined. A partially tensile-strained film deposited at 420 ℃ showed an MIT temperature (T_(MI)) of 318K whereas that of a relaxed film deposited at 520℃ was about 331K. Raman scattering measurements showed that the epitaxial strain affects the V-V vibration modes in the insulating phase. The T_(MI) in the strained film is lower as a result of the shorter V-V distance and the reduced twisting angle of the V-V dimer caused by in-plane tensile strain.