Surface reconstructions of 6H-SiC(0001) studied with scanning tunneling microscopy and core-level photo- electron spectroscopy

摘要

We have used scanning tunneling microscopy (STM) and surface-sensitive core-level spectroscopy to study the reconstructions of the Si-terminated SiC(0001) surface. For the 3~(1/2)×3~(1/2) reconstruction, obtained by heating at temperatures around 950°C, the data can be explained by a model composed of 1/3 monolayer of either Si or C adatoms in three-fold symmetric sites on top of the outermost Si-C bilayer. For surfaces heated above 1050°C, the STM images show growing fractions of quasiperiodic 5×5 and 6×6 reconstructions. Heating above 1250°C results in a partial graphitization of the surface, evident from the occurrence of a graphite component in the C 1 s spectrum and by direct observation in STM of a monocrystalline graphite overlayer which results in a modification of the 6×6 structure.