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Landscape of Charge Puddles in Graphene Nanoribbons on Hexagonal Boron Nitride
Author(s) -
Mayamei Yashar,
Shin Jae Cheol,
Watanabe Kenji,
Taniguchi Takashi,
Bae Myung-Ho
Publication year - 2020
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.202000317
Subject(s) - graphene , materials science , graphene nanoribbons , condensed matter physics , superlattice , scattering , quantum tunnelling , band gap , charge carrier , heterojunction , optoelectronics , nanotechnology , physics , optics
Recently, graphene nanoribbons (GNRs) on hexagonal boron nitride (h‐BN) substrates have been studied to develop high‐mobility devices or devices based on a 1D Moiré superlattice. For this purpose, a device‐level understanding of the charge‐puddle landscape of a GNR/h‐BN structure is needed when the charge puddles function as scattering sources for mobile charge carriers. Here, a puddle landscape is constructed on the basis of an analysis of the temperature dependencies of the conductance of GNR/h‐BN devices at various gate‐voltage values. For low‐, intermediate‐, and high‐temperature regions near the charge‐neutral point (CNP), the puddle size (50–200 nm), distance between neighboring puddles (40–170 nm), and potential depth of the puddles (in a range of 10 meV) in ∼100 nm wide GNR/h‐BN devices are obtained on the basis of Coulomb blockade, 1D variable‐range hopping, and thermally activated hopping, respectively. Based on the constructed puddle landscape, it is also concluded that the confinement‐gap energy for an ∼100 nm wide GNR is similar to that of the thermal activation energy near the CNP in the GNRs. The constructed puddle landscape for GNR/h‐BN devices is consistent with that obtained from scanning tunneling microscopy observations of graphene on an h‐BN structure.