Published in J. Electron. Mater. 43, 819 (2014).

Formation of a Buffer Layer for Graphene on C-face SiC{0001}

Guowei He, N. Srivastava, and R. M. Feenstra
Dept. Physics, Carnegie Mellon University, Pittsburgh, PA 15213

Abstract

Graphene films prepared by heating the SiC(0001) surface (the C-face of the {0001} surfaces) in a Si-rich environment are studied using low-energy electron diffraction (LEED) and low-energy electron microscopy (LEEM). Upon graphitization, an interface with √43×√43-R±7.6° symmetry is observed by in situ LEED. After oxidation, the interface displays √3×√3-R30° symmetry. Electron reflectivity measurements indicate that these interface structures arise from an graphene-like “buffer layer” that forms between the graphene and the SiC, similar to that observed on Si-face SiC. From a dynamical LEED structure calculation for the oxidized C-face surface, it is found to consist of a graphene layer sitting on top of a silicate (Si2O3) layer, with the silicate layer having the well-known structure as previously studied on bare SiC(0001) surfaces. Based on this result, the structure of the interface prior to oxidation is discussed.

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