SKM 2023 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 14: 2D Materials III (joint session HL/CPP)
HL 14.5: Talk
Tuesday, March 28, 2023, 10:30–10:45, POT 81
Hopping transport in ultraclean dual graphite gated bilayer graphene — •David Alexander Darek Emmerich1, Eike Thomas Icking1,2, Philipp Schmidt1,2, Frank Volmer1,3, Kenji Watanabe4, Takashi Taniguchi5, Bernd Beschoten1, and Christoph Stampfer1,2 — 1RWTH Aachen University, Germany — 2Forschungszentrum Jülich, Germany — 3AMO GmbH, Advanced Microelectronic Center Aachen (AMICA), Germany — 4Research Center for Functional Material, Japan — 5International Center for Materials Nanoarchitectonics, Japan
Bernal-stacked bilayer graphene (BLG) is a material that has a unique property: BLG is intrinsically a semimetal, but becomes a semiconductor under the applicaton of an out-of-plane displacement field. This controlled opening of a gate-tunable band gap makes it a promising material for realizing highly-tunable transistors and photodetectors. The limiting factor of BLG-based devices is disorder. Only by using graphitic bottom gates a true band insulating state was achieved in BLG, which exhibits a clean gap opening with faint signs of residual disorder. Using finite bias spectroscopy, we show that BLG devices with graphitic top and bottom gate electrodes exhibit extremely low disorder. We perform transport measurements down to the sub-Kelvin regime and analyse the temperature-dependent transport behaviour. For small displacement fields, where gap and disorder are expected to be of the same order of magnitude, the low-temperature hopping transport data are investigated concerning the dominant hopping mechanism.