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HL: Fachverband Halbleiterphysik

HL 21: 2D Materials II: Electronic Structure, Excitations, etc. (joint session O/CPP/HL)

HL 21.4: Vortrag

Montag, 16. März 2020, 15:45–16:00, WIL C107

Micro-focus ARPES on a twisted graphene/hBN field-effect device — •Alfred Jones¹, Ryan Muzzio², Davide Curcio¹, Deepnarayan Biswas¹, Jill A. Miwa¹, Philip Hofmann¹, Simranjeet Singh², Chris Jozwiak³, Eli Rotenberg³, Aaron Bostwick³, Roland J. Koch³, Søren Ulstrup¹, and Jyoti Katoch² — ¹Aarhus University, Aarhus, Denmark — ²Carnegie Mellon University, Pittsburgh, Pennsylvania, USA — ³Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, California, USA

Graphene/ hBN heterostructures are an ideal testing ground for functional 2D devices owing to the atomically smooth surface and weak screening offered by hBN. On top of the record mobilities this structure offers, controlling the twist angle between layers creates a superlattice effect from which exotic electronic properties can occur.

Here, I present a study of the ARPES spectrum of graphene integrated in a device architecture with a hBN dielectric and graphite gate electrode. Micron-scale ARPES based on an X-ray capillary was used to collect the Dirac spectrum at different gate-voltages. A clear, reversible doping effect up to 5*10¹² cm⁻² is observed, providing access to the doping dependent quasiparticle dynamics in graphene on hBN.

Simultaneous measurements of this gate-dependent Dirac cone dispersion and the electrical resistance of the device enables extraction of electronic mobility and lifetimes. Our approach thereby demonstrates the tantalizing prospect of combining electron transport measurements with a spectroscopic probe of the electronic structure.