Regensburg 2022 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 29: 2D Materials: Graphene

HL 29.3: Talk

Thursday, September 8, 2022, 10:00–10:15, H36

Domain determination of rhombohedral multilayer graphene devices for magnetotransport measurements — Christian Eckel, Anna Seiler, •Francesca Falorsi, Niklas Kohlrautz, and Thomas Weitz — 1. Physikalische Institut, Universität Göttingen, Friedrich-Hund Platz 1 37077 Göttingen

Graphene as the most prominent example of a 2D-material exhibits relatively different electronic band properties compared to its bulk counterpart. For monolayer, bi-layer or tri-layer the electronic properties have already been explored by multiple groups in the past. However, studies on higher layer number rhombohedral graphene (5 layers in this work) with respect to magnetoelectrical transport measurement are still pending. Finding and determining the rhombohedral domains in mechanically exfoliated flakes is the first bottleneck in the fabrication procedure. Raman spectroscopy is a well-established technique for layer number determination but often lacks a high lateral resolution. Kelvin-probe-force- microscopy (KPFM) allows a lateral resolution of the domains where the different stackings exhibit a distinguishable 15meV work function difference. Additionally, a cryogenic scanning near field optical microscopy (Cryo-SNOM) allows to depict the domains in a temperature dependent manner. The combination of all measurements will be discussed on the poster. A second challenge is the fabrication process of high quality devices for magnetotransport measurements in the milli Kelvin regime. Therefore, encapsulation in hexagonal Boron Nitride (hBN) together with graphite contacts and gates are necessary.