  Graphene nanoelectronics potential was limited by the lack of an intrinsic
bandgap[1] and attempts to tailor a bandgap either by quantum confinement or by
chemical functionalization failed to produce a semiconductor with a large
enough band gap and a sufficient mobility. It is well known that by evaporating
silicon from commercial electronics grade silicon carbide crystals an epitaxial
graphene layer forms on the surfaces [2]. The first epigraphene layer to form
on the silicon terminated face, known as the buffer layer, is insulating. It is
chemically bonded to the SiC and spectroscopic measurements [3] have identified
semiconducting signatures on the microscopic domains. However, the bonding to
the SiC is disordered and the mobilities are small. Here we demonstrate a
quasi-equilibrium annealing method that produces macroscopic atomically flat
terraces covered with a well ordered epigraphene buffer layer that has a 0.6 eV
bandgap. Room temperature mobilities exceed 5000 cm2/Vs which is much larger
than silicon and 20 times larger than the phonon scattering imposed limit of
current 2D semiconductors. Critical for nanotechnology, its lattice is aligned
with the SiC substrate, it is chemically, mechanically, and thermally robust,
and it can be conventionally patterned and seamlessly connected to semimetallic
epigraphene making semiconducting epigraphene ideally suited for
nanoelectronics.
