Temperature Dependence of Epitaxial Graphene Formation on SiC(0001)
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The formation of epitaxial graphene on SiC(0001) surfaces is studied using atomic force microscopy, Auger electron spectroscopy, electron diffraction, Raman spectroscopy, and electrical measurements. Starting from hydrogen-annealed surfaces, graphene formation by vacuum annealing is observed to begin at about 1150°C, with the overall step-terrace arrangement of the surface being preserved but with significant roughness (pit formation) on the terraces. At higher temperatures near 1250°C, the step morphology changes, with the terraces becoming more compact. At 1350°C and above, the surface morphology changes into relatively large flat terraces separated by step bunches. Features believed to arise from grain boundaries in the graphene are resolved on the terraces, as are fainter features attributed to atoms at the buried graphene/SiC interface.
KeywordsGraphene silicon carbide semiconductor field-effect transistor
- 12.Although the morphology of Fig. 3a is quite similar to that seen in Ref. 5, the annealing temperature reported there is higher (1300°C) and graphene thickness greater (1.5 ML) than the present work. It should be noted however that the starting surface in Ref. 5 is different, since the sample was transferred through air between H-etching and graphitization and also a small amount of surface metal contamination was present. Additionally, some uncertainty in temperature determination occurs in both experiments.Google Scholar
- 17.S. Nie (Ph.D. Thesis, Department of Physics, Carnegie Mellon University, 2007).Google Scholar
- 23.S. Nie and R.M. Feenstra, J. Vac. Sci. Technol. B, submittedGoogle Scholar