Work function and conductivity changes due to molecular adsorption in epitaxial graphene on 6H-SiC

Charge carrier transport properties and molecular doping in graphene grown epitaxially on both Si and C-faces of 6H-SiC have been investigated. Our results indicate that in C-face multiplayer graphene (MLG) p-type charge carriers are dominant and in Si-face few layer graphene (FLG), charge carriers are mostly n-type. A strong correlation between conductance change and SWF change due to molecular doping in C and Si-faces epitaxial graphene has been found based on type of carrier, Fermi level shifts, and carrier density of the graphene film. An analytical model for the dependence of conductivity on the adsorbate-induced doping and impurities is being developed based on work function change and Boltzmann transport theory.