Regensburg 2025 – scientific programme

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O: Fachverband Oberflächenphysik

O 37: Poster 2D Materials Beyond Graphene: Growth, Structure and Substrate Interaction (joint session O/HL)

O 37.1: Poster

Tuesday, March 18, 2025, 13:30–15:30, P3

Two-dimensional hexagonal β-GeSe on Au(111) — •Dina Wilks, Veronika Blecker, Muhammad Ali Martuza, Marina Hammer, Christoph Schuster, Paulus Aleksa, and Carsten Busse — Walter-Flex-Straße 3, 57072 Siegen, Germany

Two-dimensional (2D) group-IV monochalcogenides (general form MX with M=Sn, Ge; X=S, Se, Te) demonstrate a high degree of polymorphism. While the orthorhombic phase, widely studied for its in-plane ferroelectricity, holds significant promise, experimental studies on other polymorphs remain scarce.
Here, we investigate the growth and structure of 2D hexagonal β-GeSe on Au(111). This phase is predicted to exhibit out-of-plane ferroelectricity, which could be more technologically feasible for device integration. Samples are prepared using molecular beam epitaxy (MBE) with GeSe powder as the source material and analyzed with low energy electron diffraction (LEED) and scanning tunneling microscopy (STM). The degree of structural order was found to depend sensitively on the heat treatment. We observe a (5 × 5) superstructure relative to Au(111), accompanied by a continuously varying density of states (DOS) across the superstructure’s unit cell. Additionally, an intriguing self-similar pattern emerges, which can be attributed to antiphase grain boundaries. These boundaries exhibit metallic behaviour near the Fermi level, highlighting their potential significance in the electronic properties of the system.

Keywords: GeSe; group-IV monochalcogenides; STM; LEED; Au(111)