Control of the graphene growth rate on capped SiC surface under strong Si confinement

The effect of the degree of Si confinement on the thickness and morphology of UHV grown epitaxial graphene on (0 0 0 - 1) SiC is investigated by using atomic force microscopy and Raman spectroscopy measurements. Prior to the graphene growth process, the C-face surface of a SiC substrate is capped by another SiC comprising three cavities on its Si-rich surface with depths varying from 0.5 to 2 microns. The Si atoms, thermally decomposed from the sample surface during high temperature annealing of the SiCcap/SiCsample stack, are separately trapped inside these individual cavities at the sample/cap interface. Our analyses show that the growth rate linearly increases with the cavity height. It was also found that stronger Si confinement yields more uniform graphene layers. (C) 2012 Elsevier B.V. All rights reserved.