Structural and electrical properties of VO2/ZnO nanostructures

We examined the structural and electrical properties of uniformly-oriented VO2/ZnO nanostructures. VO2 was deposited on ZnO templates by using a direct current-sputtering deposition. Scanning electron microscope and transmission electron microscope measurements indicated that b-oriented VO2 were uniformly crystallized on ZnO templates with different lengths. VO2/ZnO formed nanorods on ZnO nanorods with length longer than 250 nm. X-ray absorption fine structure at the V K edge of VO2/ZnO showed M1 and R phases of VO2 at 30 and 100 °C, respectively, suggesting structural-phase transition occurring between the two temperatures. Temperature-dependent resistance measurements of VO2/ZnO nanostructures revealed metal-to-insulator transition at 65 °C and 55 °C during a heating and a cooling, respectively, regardless of ZnO length. Asymmetry behavior of resistance curves from VO2/ZnO nanostructure during a heating and a cooling was attributed from a strong bond of VO2 and ZnO.