Tunable moiré bandgap in hBN-aligned bilayer graphene device with in-situ electrostatic gating
arxiv(2024)
Abstract
Over the years, great efforts have been devoted in introducing a sizable and
tunable band gap in graphene for its potential application in next-generation
electronic devices. The primary challenge in modulating this gap has been the
absence of a direct method for observing changes of the band gap in momentum
space. In this study, we employ advanced spatial- and angle-resolved
photoemission spectroscopy technique to directly visualize the gap formation in
bilayer graphene, modulated by both displacement fields and moiré potentials.
The application of displacement field via in-situ electrostatic gating
introduces a sizable and tunable electronic bandgap, proportional to the field
strength up to 100 meV. Meanwhile, the moiré potential, induced by aligning
the underlying hexagonal boron nitride substrate, extends the bandgap by 20
meV. Theoretical calculations, effectively capture the experimental
observations. Our investigation provides a quantitative understanding of how
these two mechanisms collaboratively modulate the band gap in bilayer graphene,
offering valuable guidance for the design of graphene-based electronic devices.
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