Science Daily April 11, 2024
Studies of electric field-driven insulator-to-metal (IMT) in the prototypical vanadium dioxide (VO2) thin-film channel devices are largely focused on the electrical and elastic responses of the films, but the response of the corresponding Titanium dioxide (TiO2) substrate is often overlooked. An international team of researchers (USA – Pennsylvania State University, Cornell University, Argonne National Laboratory, Germany) found that in-operando spatiotemporal imaging of the coupled elastodynamics using X-ray diffraction microscopy of a VO2 film channel device on TiO2 substrate the film channel bulged during the IMT instead shrinking as expected. A micron thick proximal layer in the substrate coherently bulged accompanying the IMT in the film. Phase-field simulations of coupled IMT suggested that the observed elastodynamics could be explained by the known naturally occurring oxygen vacancies that rapidly ionized (and deionized) in concert with the IMT. According to the researchers, fast electrical-triggering of the IMT via ionizing defects and an active “IMT-like” substrate layer are critical aspects to consider in device applications… read more. Open Access TECHNICAL ARTICLE
a) Schematic of the in-operando synchrotron X-ray imaging setup at the beamline… Credit: Advanced Materials, 05 March 2024