Three-phase metal-insulator transition and structural alternative for a VO2 film epitaxially grown on Al2O3(0001)

摘要: We report on the crystallographic phases and their epitaxial relationships observed during metal-insulator transition (MIT) of a VO 2 film deposited Al 2O 3(0001). A key feature this work is to establish two possible in-plane for film, introducing an “on-axis” “diagonal” model. These models have distinctive signatures in reciprocal spaces form multiplet reflections can, therefore, be easily differentiated by diffraction. They serve as basis interpreting results gained high-resolution X-ray diffraction, complemented Raman spectroscopy, 420-nm-thick grown microwave plasma-assisted reactive sputtering address its orientation follow structure through MIT. The oriented according diagonal model exhibits MIT involving three with different temperature domains (co)existence. room- high-temperature are, respectively, identified monoclinic M1 rutile R polymorphs 2. Additionally, we observe that when sample resistivity starts decrease, insulating phase turns into intermediary phase, which then partially transforms metallic complete. similar M2 polymorph 2, lattice parameters, signature, known proximity tensile conditions. mixing still detected at 110 ° C, i.e., far above MIT; being probably stabilized interface between substrate, where interfacial strain higher.