  We fabricate a vertical thin-film barristor device consisting of highly doped
silicon (gate), 300 nm SiO2 (gate dielectric), monolayer graphene, pentacene,
and a gold top electrode. We show that the current across the device is
modulated by the Fermi energy level of graphene, tuned with an external gate
voltage. We interpret the device current within the thermionic emission theory,
showing a modulation of the energy barrier between graphene and pentacene as
large as 300meV.
