X-ray diffraction study of electric field-induced metal-insulator transition of vanadium dioxide film on sapphire substrate

An X-ray diffraction study of the electric field-induced metal-insulator transition (MIT) of a vanadium dioxide (VO2) film on a sapphire (001) substrate, which exhibited MIT at a temperature of approximately around 68 degrees C with a three-order change in resistivity, was performed. A simple device fabricated using a VO2 film having aluminum electrodes as ohmic contacts with a gap separation of 1.0 mm showed current jump at an applied voltage of 48 V. The X-ray diffraction of an in situ electrically biased VO2 film in transition state showed a crystalline structure change from monoclinic VO2 to tetragonal VO2 when compliance current was higher than a certain value. We found that this macroscopic crystalline structure change is not induced by electric field in the case of the lowest compliance current, indicating the significance of the current for fast and durable operation of VO2-based devices.