SKM 2021 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 9: Focus Session: Highlights of Materials Science and Applied Physics II (joint session DS/HL)
DS 9.3: Vortrag
Freitag, 1. Oktober 2021, 10:30–10:45, H1
Surface reconstructions: challenges and opportunities for the growth of perovskite oxides — Giada Franceschi, Michael Schmid, Ulrike Diebold, and •Michele Riva — Institute of Applied Physics, TU Wien, Austria
Achieving atomically flat and stoichiometric films of complex multicomponent oxides is crucial for integrating these materials in emerging technologies. While pulsed laser deposition (PLD) can in principle produce these high-quality films, experiments often show rough surfaces and nonstoichiometric compositions.
To understand the cause, we follow the growth at the atomic scale from its early stages, using STM. We focus on SrTiO3(110) and La0.8Sr0.2MnO3(110) films. For both, the non-stoichiometries introduced during growth accumulate at the surface. As a result, their surface structure evolves along phase diagrams of surface structure vs. composition [1,2,3]. This can drastically degrade the surface morphology: pits develop on reconstructed areas with different sticking [4]; ill-defined oxide clusters nucleate when the non-stoichiometry introduced is too large to be accommodated in the surface by changing its structure. On the flip side, one can take advantage of the high sensitivity of surface structures to composition deviations to grow films with thickness of several tens of nanometers retaining atomically flat surfaces, and with stoichiometry control better than 0.1% [1].
[1] Phys. Rev. Mater. 3, 043802 (2019). [2] J. Mater. Chem. A 8, 22947 (2020). [3] arXiv:2010.05205 (2020). [4] Phys. Rev. Res. 1, 033059 (2019).