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O: Fachverband Oberflächenphysik

O 89: Poster Session - Oxide and Insulator Surfaces: Structure, Epitaxy and Growth

O 89.2: Poster

Mittwoch, 18. März 2020, 18:15–20:00, P2/1OG

Morphological study of vanadium dioxide (VO₂) thin films grown on the different substrates using STM — •Aman Baunthiyal, Simon Fischer, Jon-Olaf Krisponeit, and Jens Falta — Institute of Solid State Physics, University of Bremen, Germany

Vanadium dioxide (VO₂) is an interesting material for sensor and memory devices due to its metal-insulator transition (MIT) near room temperature (RT) that is accompanied by a structural change between a monoclinic insulator phase and a rutile metallic phase. This temperature can be varied by the choice of the substrate: TiO₂(110) and RuO₂(110) applies in-plane tensile strain to the rutile c-axis which leads to an increase of the transition temperature of VO₂, favoring the monoclinic phase.

RuO₂(110) islands were formed on the surface of a Ru crystal by oxidizing it while observing with in-situ LEEM and LEED. Then, VO₂ was deposited using molecular beam epitaxy (MBE). VO₂ growth on TiO₂(110) substrate was grown through the same process. To study the surface morphology of VO₂ grown on RuO₂(110) and TiO₂(110), we used STM (scanning tunneling microscope) at RT. In the case of VO₂/RuO₂, the surface of VO₂ was found flat with two rotational domains separated by 60 degrees. The thickness of VO₂ on RuO₂ was measured to be about 3 to 4 nm using XRR (X-ray Reflectometry). In the case of VO₂/TiO₂ , the surface was also found to be flat but showing small grains of VO₂ on the TiO₂ surface. Next, we intend to study the effect of different substrates on the MIT transition of VO₂ by variable temperature STM (VT-STM) using single-point spectroscopy.