Published in J. Phys. D: Appl. Phys. 45, 154001 (2012).
Graphene formed on SiC under various environments: Comparison of Si-face and C-face
N. Srivastava (a), Guowei He (a), Luxmi (a), P. C. Mende (a), R. M. Feenstra (a),
and Yugang Sun (b)
(a) Dept. Physics, Carnegie Mellon University, Pittsburgh, PA 15213
(b) Center for Nanoscale Materials, Argonne National Laboratory, Argonne, IL 60439
Abstract
The morphology of graphene on SiC {0001} surfaces formed in various environments including ultra-high vacuum, 1 atm of argon, and 10-6 to 10-4 Torr of disilane is studied by atomic force microscopy, low-energy electron microscopy, and Raman spectroscopy. The graphene is formed by heating the surface to 1100 – 1600 C, which causes preferential sublimation of the Si atoms. The argon atmosphere or the background of disilane decreases the sublimation rate so that a higher graphitization temperature is required, thus improving the morphology of the films. For the (0001) surface, large areas of monolayer-thick graphene are formed in this way, with the size of these areas depending on the miscut of the sample. Results on the (0001) surface are more complex. This surface graphitizes at a lower temperature than for the (0001) surface and consequently the growth is more three-dimensional. In an atmosphere of argon the morphology becomes even worse, with the surface displaying markedly inhomogeneous nucleation, an effect attributed to unintentional oxidation of the surface during graphitization. Use of a disilane environment for the (0001) surface is found to produce improved morphology, with relatively large areas of monolayer-thick graphene.
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