SKM 2023 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 14: Nanostructures at Surfaces (joint session O/CPP)
O 14.9: Vortrag
Montag, 27. März 2023, 17:00–17:15, GER 39
Analytical electron microscopy of nanostructured vanadium dioxide — •Vlastimil Křápek1, Jan Krpenský1,2, Michal Horák1, Katarína Rovenská1, Peter Kepič1, Tomáš Šikola1, Filip Ligmajer1, and Andrea Konečná1 — 1Brno University of Technology, Czechia — 2CIC nanoGUNE, San Sebastián, Spain
Vanadium dioxide (VO2) is a phase-changing material exhibiting temperature-induced metal-insulator transition (MIT) around 340 K. A rather low transition temperature makes VO2 a suitable material for active nanophotonics, e.g., switchable optical metasurfaces. Such applications require nanostructuring of VO2 thin films. Here we study the possibility to employ focused ion beam (FIB) milling for the nanofabrication and its impact on the properties of resulting nanostructures.
Taking the VO2 thin film with experimentally verified MIT, we utilized FIB milling with Ga ions to fabricate V-shaped lamella of the thickness between 0 and 250 nm, which was subsequently transferred onto a heating chip for transmission electron microscopy and analyzed with analytical electron microscopy: high-resolution imaging, energy-dispersive X-ray spectroscopy, and temperature-dependent electron energy loss spectroscopy. We observed a porous character of the pristine material, a coexistence of several crystal structures, negligible contamination with Ga ions, and a variation of stoichiometry with the thickness of the lamella, with the thinnest parts composed of VO and V2O3.