Atomic and electronic structures of heat treated 6H-SiC surface

We have studied heat-treated (950-1300°C) 6H-SiC(0001)Si and (0001)C face with photoemission spectroscopy using synchrotron radiation (SR-PES) and low energy electron diffraction (LEED). We observed LEED patterns of SiC 1 X 1, √3 X √3, √3 x √3 + 6√3 x 6√3 and graphite 1 X 1 sequentially with increasing heating temperature for (0001)Si face and SiC 1 X 1 for (0001)C face, respectively. We have measured Si(2p) spectra and valence band energy distribution curves (VB-EDCs). The trend of sublimation of Si atoms from surface is different between Si- and C-face. √3 x √3 superstructure must be Si-derived. The 6√3 x 6√3 structure could be explained as a moire pattem caused by monolayer-graphite sitting on SiC surface. Si 3s-derived state of SiC 1 x 1 is different between SiC 1 X I for Si- and C-face. It is suggested that a single crystal graphite layer grows on Si-face and a polycrystalline graphite is formed on C-face for heated specimens above 1150°C.