Regensburg 2022 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 29: 2D Materials: Graphene
HL 29.2: Vortrag
Donnerstag, 8. September 2022, 09:45–10:00, H36
Direct observation of ultraclean tunable band gaps in bilayer graphene — •Eike Thomas Icking1,2, Luca Banszerus1,2, Philipp Schmidt1,2, Corinne Steiner1,2, Frederike Wörtche1, Frank Volmer1, Stephan Engels1,2, Jonas Hesselmann1, Matthias Goldsche1,2, Kenji Watanabe3, Takashi Taniguchi4, Christian Volk1,2, Bernd Beschoten1, and Christoph Stampfer1,2 — 1RWTH Aachen University, Germany — 2Forschungszentrum Jülich, Germany — 3Research Center for Functional Material, Japan — 4International Center for Materials Nanoarchitectonics, Japan
Control over the charge carrier density and the band gap size of a semiconductor paves the way for a wide range of applications, such as highly-tunable transistors, photodetectors, and lasers. Bernal-stacked bilayer graphene (BLG) allows tuning the band gap by an out-of-plane electric displacement field. The first evidence of this unique band gap tunability was found ten years ago, but it took until recently to fabricate sufficiently clean heterostructures to use the band gap to suppress electric current or confine charge carriers. We present a detailed study of the tunable band gap in gated BLG characterized by temperature-activated transport and finite-bias spectroscopy measurements. The latter method allows comparing different gate materials and device technologies that directly affect the effective disorder potential. We show that in graphite-gated BLG there are as good as no sub-gap states resulting in ultraclean band gaps with values in good agreement with theory, allowing to achieve band gaps up to 120 meV.