Abstract

Low energy electron diffraction, Auger electron spectroscopy, high resolution electron energy loss spectroscopy and scanning tunnelling microscopy investigations used for structure and morphology determinations of different hexagonal SiC surfaces are presented. The analyses include sample orientation, layer stacking, step morphology, layer spacings as well as the species and coordination of surface terminating adatoms. The samples were prepared ex situ and investigated without further treatment. Predominant ABCACB stacking is found for 6H-SiC(0001) corresponding to a triple step morphology. The surface is covered by hydroxyl species bound to the topmost Si atoms. The surface of a 3C-SiC(111) sample was found to be covered by oxygen on only 50% of the available Si sites. On both surfaces the first bilayer is slightly compressed on an otherwise bulk-like geometry. 6H-SiC(0001) exhibits a single step morphology in agreement with the mixed stacking found on the surface. All three possible surface stacking sequences are present in equal amounts.

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