OPTICAL PROPERTIES OF VANADIUM DIOXIDE GROWN ON SAPPHIRE SUBSTRATE WITH DIFFERENT ORIENTATIONS

摘要

We report optical, structural, and electrical properties of VO_2 on sapphire substrates with c-, m-and r- orientations with identical growth conditions. XRD data show that VO_2 orientation depends on the substrate orientation. Based on temperature-dependent resistivity measurements, metal-insulator phase transition(MIT)temperature, T_(MIT), depends on the VO_2 orientation due, primarily, to stress. The energy gap E_g is observed to gradually red shift as temperature increases before collapsing to E_g ≈0 eV at temperatures below T_(MIT).