THE (0001)-SURFACE OF 6H-SIC - MORPHOLOGY, COMPOSITION AND STRUCTURE

The morphology, composition and structure of wet chemically prepared 6H-SiC(0001) samples were investigated immediately after introduction into vacuum. Scanning tunneling microscopy displayed large atomically flat areas on the surface. The step structure found is correlated to the sample periodicity normal to the surface. Most step heights are multiples of half the vertical unit cell length. Low-energy electron diffraction (LEED) revealed good surface order with bulk-like lateral periodicity. From high-resolution electron energy loss spectroscopy the saturation of dangling bonds with hydroxyl species could be determined. This termination is responsible for an electron beam sensitivity found in LEED. Upon annealing the oxygen is removed and carbon-carbon bonds develop on the surface as demonstrated by Auger electron spectroscopy. This new structure is ordered in a (root 3 X root 3)R30 degrees periodicity.