p-Type Electrical Transport of Chemically Doped Epitaxial Graphene Nanoribbons

We present the first demonstration of p-type electrical transport in chemically doped epitaxial graphene (EG) nanoribbons produced on silicon carbide (SiC). The thermal annealing of cross-linked thin films of hydrogen silsesquioxane (HSQ) is found to be capable of overcoming intrinsic n-type doping from the SiC substrate, resulting in p-type functionality. A smooth transition from n- to p-type carriers, spanning a Fermi shift of 0.45 eV, is observed by controlling the density and chemical composition of HSQ. This technique provides a route for complementary transistor and interconnect fabrication, as well as facilitating chemically doped p-n junctions in EG.