Fluorine functionalization of epitaxial graphene for uniform deposition of thin high-κ dielectrics

Fluorine functionalization, using XeF2, was investigated as a way to enhance atomic layer deposition (ALD) of thin, high-kappa dielectrics on epitaxial graphene, which would enable the realization of graphene-based device technologies. The XeF2 dosage time was correlated with oxide coverage and morphology as well as its overall effect on the underlying graphene properties. An optimum XeF2 dose time of 120 s (P-XeF2 = 1 torr, P-N2 = 35 torr) was found to form C-F bonds on 6-7% of the graphene surface, which are presumed to act as additional ALD reaction sites facilitating conformal Al2O3 films only 15 nm thick. Under these optimal conditions, the graphene lattice remained essentially undisturbed and the Hall mobility exhibited a 10-25% increase after oxide deposition. These results indicate that this novel technique is a viable path to obtaining ultrathin high-kappa dielectrics by ALD on epitaxial graphene. (C) 2012 Elsevier Ltd. All rights reserved.