SKM 2023 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 56: 2D Materials III: Growth, Structure and Substrate Interaction II (joint session O/CPP)
O 56.6: Vortrag
Mittwoch, 29. März 2023, 16:15–16:30, GER 37
Structure determination of mono- and few-layers of the 2D-ferroelectric SnSe on graphene on Ir(111) — •Dina Wilks1, Paulus Aleksa1, Simon Chung2, Peter Modregger1, Dmitri V. Novikov3, Vedran Vonk2, Andreas Stierle2,4, and Carsten Busse1 — 1Physics Department, University of Siegen, Germany — 2Nanolabor Centre for X-ray and Nano Science CXNS, Germany — 3Deutsches Elektronen-Synchrotron DESY, Germany — 4Physics Department, University of Hamburg, Germany
For conventional ferroelectrics the critical temperature Tc quickly falls below technically feasible values for very thin films. This is not the case for two-dimensional materials. Theory predicts strong ferroelectricity for group-IV monochalcogenides, where individual layers are puckered sheets with a phosphorene-like structure. For SnSe, stable ferroelectricity of monolayers at room temperature has been shown by controlled microscopic manipulation. Here, we provide the missing structure determination of these monolayers.
We use surface X-ray diffraction to determine the structure of SnSe mono- and few-layers, the influence of the substrate, and the difference in stacking between a few-layered system and the bulk. SnSe films are prepared by MBE using graphene on Ir(111) as an inert and weakly interacting substrate. We observe one phase with three different orientations of monolayer SnSe islands with respect to graphene, while for the few-layered system two phases are found, each with three different orientations. A change in structure with rising temperature for both systems is seen, which hints towards Tc.