Dresden 2020 – scientific programme

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O: Fachverband Oberflächenphysik

O 10: Oxides I: Growth and Characterization

O 10.7: Talk

Monday, March 16, 2020, 12:00–12:15, WIL B321

Non-stoichiometry segregation in perovskite oxides and its role for film growth — •Giada Franceschi, Michael Schmid, Ulrike Diebold, and Michele Riva — TU Wien, Institute of Applied Physics, Wiedner Haupstrasse 8-10/E134, 1040, Vienna, 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, growth experiments often result in rough surfaces and nonstoichiometric compositions. To understand the cause, we follow the growth at an atomic level from its early stages as a function of the growth conditions, using atomically resolved STM. We investigate the growth of SrTiO₃(110) and La_0.8Sr_0.2MnO₃(110) films. Both accumulate small non-stoichiometries introduced during growth at the surface. As a result, their surface structure evolves along phase diagrams of surface structure vs. composition.[1] This can produce dramatic effects on the surface morphology: If two surface reconstructions with different sticking properties develop and coexist during growth, pits can form, degrading the surface morphology.[2] Moreover, if the introduced non-stoichiometry is too large to be accommodated by the surface via a change in its structure, ill-defined oxide clusters nucleate and grow, eventually dominating the surface morphology. We show our approach to grow films with thickness of tens of nanometers showing atomically flat surfaces, and with stoichiometry control within 0.1%.[1] [1] PRMater. 3, 043802 (2019) [2] PRResearch 1, 033059 (2019)