Fluorine functionalization of epitaxial graphene for uniform deposition of thin high-κ dielectrics
2012
Wheeler, Virginia | Garces, Nelson | Nyakiti, Luke | Myers-Ward, Rachael | Jernigan, Glenn | Culbertson, James | Eddy, Charles, Jr | Kurt Gaskill, D.
Fluorine functionalization, using XeF₂, was investigated as a way to enhance atomic layer deposition (ALD) of thin, high-κ 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 120s (PXₑF₂=1torr, PN₂=35torr) 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 15nm 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-κ dielectrics by ALD on epitaxial graphene.
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