Morphology and atomic structure of SiC(0001) surfaces: a UHV STM study

Scanning tunnelling microscopy (STM) in UHV has been used to study morphology and atomic structure of the (0001) surfaces of 6H and 4H silicon carbide. After annealing under silicon flux at temperatures of 850–1100 °C the surface always showed 3 × 3 reconstruction. Surplus silicon atoms aggregate heteroepitaxially into islands. Upon further annealing without silicon flux the surface structure exhibits many different reconstructions and after about 15 min turns into √3 × √3R30°. The shape of the SiC-islands and depressions on the surface displayed a common dependence on temperature. At lower temperatures they are rather rough. At higher temperatures they become more straight and maximize directions with a minimum number of dangling bonds.