  Using ab-initio methods we investigate the possibility of three-terminal
graphene "T-junction" devices and show that these all-graphene edge contacts
are energetically feasible when the 1D interface itself is free from foreign
atoms. We examine the energetics of various junction structures as a function
of the atomic scale geometry. Three-terminal equilibrium Green's functions are
used to determine the transmission spectrum and contact resistance of the
system. We find that the most symmetric structures have a significant binding
energy, and we determine the contact resistances in the junction to be in the
range of 1-10 kOhm which is comparable to the best contact resistance reported
for edge-contacted graphene-metal contacts. We conclude that conducting
all-carbon T-junctions should be feasible.
