The atomic structure of silicon carbide surfaces in hexagonal orientation was investigated with the main emphasis on surface morphology and dangling-bond saturation either by ad-species or by surface reconstruction. By using quantitative low-energy electron diffraction intensity analysis, the atomic geometry immediately after ex situ chemical treatment was determined for 4H and 6H samples in both hexagonal orientations and a 3C−SiC(111) surface. The step structure was found to be directly related to the polytype of the samples from morphology studies by using scanning-tunnelling microscopy. This was in agreement with the surface layer stacking sequence determined in the low-energy electron diffraction analysis. Dangling bonds of the topmost surface atoms were fully saturated by adspecies that remain from the chemical preparation. Reconstruction phases prepared under ultra-high vacuum conditions were investigated using the in situ combination of low-energy electron diffraction and scanning tunnelling microscopy. Here the number of dangling bonds was reduced by a reconstruction pattern that involves adatoms or adclusters for the more silicon rich-phases and by a commensurate overlayer of large periodicity in the more carbon-rich structures.

Morphology, Bond Saturation and Reconstruction of Hexagonal SiC Surfaces. U.Starke, J.Schardt, M.Franke: Applied Physics A, 1997, 65, 587–96