Boosting the carrier mobility of graphene
Prof. Christoph Stampfer, RWTH Aachen University and Forschungszentrum Jülich
The carrier mobility is an important figure of merit for electrical conductors, characterizing how quickly a charge can move in response to an electric field. Thanks to the suppression of backscattering guaranteed by pseudo-spin conservation, graphene outperforms all known materials in terms of room temperature mobility. In this talk I will provide a review of the fundamental properties leading to the exceptionally high carrier mobilities and in particular I will show that the best performance of state-of-the-art graphene devices -- which is close to the theoretical limit set by electron-phonon scattering -- can be surpassed by more than a factor four employing van-der-Waals heterostructures consisting of tungsten diselenide (WSe2), graphene and hexagonal boron nitride. This enhancement, which leads to a room temperature mobility of 350,000 cm2/(Vs), can be understood in terms of the suppression of electron-phonon scattering due to the mechanical coupling between graphene and tungsten diselenide, which converts graphene's acoustic phonon branches into finite-energy interlayer shear modes.