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Influence of substrate type and quality on carrier mobility in graphene nanoribbons

We report the results of a thorough numerical study on carrier mobility in graphene nanoribbons (GNRs) with the widths from ~250 nm down to ~1 nm, with a focus on the influence of substrate type (SiO2, Al2O3, HfO2 and h-BN) and substrate quality (different interface impurity densities) on GNR mobility. We identify the interplay between the contributions of Coulomb and surface optical phonon scattering as the crucial factor that determines the optimum substrate in terms of carrier mobility. In the case of high impurity density (~10^13 cm^−2), we find that HfO2 is the optimum substrate irrespective of GNR width. In contrast, for low impurity density (10^10 cm^−2), h-BN offers the greatest enhancement, except for nanoribbons wider than ~200 nm for which the mobility is highest on HfO2.

graphene nanoribbons; mobility; momentum relaxation time; numerical modeling

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