Regensburg 2025 – scientific programme

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O: Fachverband Oberflächenphysik

O 33: Poster Graphene: Electronic Structure and Excitations

O 33.12: Poster

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

Near-Field Optical spectroscopy of few-layer Graphene’s interband resonances to study it’s gate-tunable band structures — •Dominique Malik, Lina Jäckering, and Thomas Taubner — I. Institute of Physics (IA), RWTH Aachen University

The band structure of few-layer graphene (FLG) defined by the crystallographic stacking order determines its electronic and optical properties. Optical spectroscopy of interband resonances - the excitation of electron transitions between two electronic bands - allows to directly probe the gate-tunable band structure. Within one flake FLG can exist in different stacking orders. However, conventional far-field spectroscopy is diffraction limited and cannot resolve stacking domains below this limit [1]. Recently, with scanning near-field optical microscopy (s-SNOM) the interband resonances of bilayer graphene (BLG) and 4LG have been retrieved [2]. Due to the stacking specific resonance energy, s-SNOM spectroscopy allowed for the identification of stacking domains on the nanometer scale [2]. The local effect of the application of a gate voltage to FLG has not been studied. Here, we present the theoretical foundation to perform near-field optical spectroscopy of interband resonances of gated trilayer and BLG over the energy range from 0.28 to 0.54 eV to gain insights into gate-tunable modifications of their band structures. We layout the design and fabrication of a suitable sample and show initial results. We expect high-resolution s-SNOM measurements could reveal local variations in band gap opening, which are unachievable with far-field techniques. [1] Lui et al. Nano Lett. 11, 1 (2011) [2] Wirth et al. ACS Photonics 8.2 (2021)