Regensburg 2022 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 22: 2D Materials 8 (joint session DS/CPP)
DS 22.8: Vortrag
Donnerstag, 8. September 2022, 11:15–11:30, H17
Impact of opto-electronic measurements on the properties of hexagonal boron nitride as a dielectric — •Jo Bertram1, Luca Kotewitz1, Manfred Ersfeld1, Frank Volmer1, Kenji Watanabe2, Takashi Taniguchi3, Christoph Stampfer1, and Bernd Beschoten1 — 12nd Institute of Physics and JARA-FIT, RWTH Aachen University, 52074 Aachen, Germany — 2Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan — 3International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
Hexagonal boron nitride (hBN) serves as an atomically flat, insulating substrate for a large variety of 2D heterostructures. However, recent opto-electronic experiments showed that optically triggered leakage currents passing through hBN pose a serious bottleneck for reliable gating of 2D semiconductors [1]. Motivated by these observations, we report on photo-induced charge transport through hBN in graphite-hBN-graphite devices. Furthermore, we examine the impact of illuminating hBN employed as a gate dielectric on the charge carrier density of graphene Hall bar devices. Our results indicate that hBN exhibits optically active electronic states, which partially screen the gate electric field under light illumination. Interestingly, we observe a strong asymmetry of this effect for positive and negative electric fields showing that hBN does not behave as an ideal dielectric within the plate capacitor model especially in opto-electronic experiments.
[1] F. Volmer et al., Phys. Status Solidi RRL 14, 2000298 (2020)