Thin vanadium oxide films were made by vacuum evaporation followed by the annealing posttreatment in the presence of air. The thickness increased by a factor as large as ∼2.3 on oxidation. Electron diffractograms indicated a bcc → monoclinic transformation during the annealing, and electron micrographs showed pronounced grain growth. Temperature-dependent electrical conductivity as well as spectral transmittance was measured vs annealing time. At an initial thickness of 0.12 µm, it took a few hours to establish VO2 films with a well defined semiconductor–metal transition and concomitant thermochromic switching at ∼57°C.
© 1991 Optical Society of America
S.-J. Jiang, C.-B. Ye, M. S. R. Khan, and Claes-Goran Granqvist, "Evolution of thermochromism during oxidation of evaporated vanadium films," Appl. Opt. 30, 847-851 (1991)