Accurate Measurement of the Gap of Graphene / h − BN Moiré Superlattice through Photocurrent Spectroscopy

Accurate Measurement of the Gap of Graphene / h − BN Moiré Superlattice through Photocurrent Spectroscopy

Monolayer graphene aligned with hexagonal boron nitride (h-BN) develops a gap at the charge neutrality point (CNP). This gap has previously been extensively studied by electrical transport through thermal activation measurements. Here, we report the determination of the gap size at the CNP of graphe...

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Bibliographic Details
Main Authors: Han, Tianyi, Yang, Jixiang, Zhang, Qihang, Wang, Lei, Watanabe, Kenji, Taniguchi, Takashi, McEuen, Paul L, Ju, Long
Other Authors: Massachusetts Institute of Technology. Department of Physics
Format: Article
Language:English
Published: American Physical Society (APS) 2022
Online Access:https://hdl.handle.net/1721.1/141954
Description
Summary:Monolayer graphene aligned with hexagonal boron nitride (h-BN) develops a gap at the charge neutrality point (CNP). This gap has previously been extensively studied by electrical transport through thermal activation measurements. Here, we report the determination of the gap size at the CNP of graphene/h-BN superlattice through photocurrent spectroscopy study. We demonstrate two distinct measurement approaches to extract the gap size. A maximum of ∼14  meV gap is observed for devices with a twist angle of less than 1°. This value is significantly smaller than that obtained from thermal activation measurements, yet larger than the theoretically predicted single-particle gap. Our results suggest that lattice relaxation and moderate electron-electron interaction effects may enhance the CNP gap in graphene/h-BN superlattice.

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