Graphene Ohmic Contacts to n-Type Silicon Carbide (0001)

Abstract

Epitaxial graphene on silicon carbide (SiC) can easily be grown by thermal decomposition. A well-defined epitaxial interface between graphene and substrate is formed, especially when the silicon face of hexagonal polytypes is employed. It is found that as-grown monolayer graphene with interfacial buffer layer provides perfectly ohmic contacts to n-type SiC – even to low-doped epitaxial layers without contact implantation. Contact resistances to highly doped samples are competitive with conventional annealed nickel (Ni) contacts; a direct comparison of Ni and graphene contacts on 4H-SiC resulted in an one order of magnitude reduction of the contact resistance in the case of graphene contacts. On highly doped 6H-SiC, a specific contact resistance as low as ρC = 5.9·10-6 Ωcm2 was found. This further improvement compared to 4H-SiC is assigned to better matching of work functions at the Schottky-like interface.