MORPHOLOGY AND ATOMIC-STRUCTURE OF SIC(0001) SURFACES - A UHV STM STUDY

Scanning tunnelling microscopy (STM) in UHV has been used to study mor phology and atomic structure of the (0001) surfaces of 6H and 4H silic on carbide. After annealing under silicon flux at temperatures of 850- 1100 degrees C the surface always showed 3 x 3 reconstruction. Surplus silicon atoms aggregate heteroepitaxially into islands. Upon further annealing without silicon flux the surface structure exhibits many dif ferent reconstructions and after about 15 min turns into root 3 x root 3R30 degrees. The shape of the SiC-islands and depressions on the sur face displayed a common dependence on temperature. At lower temperatur es they are rather rough. At higher temperatures they become more stra ight and maximize directions with a minimum number of dangling bonds. (C) 1997 Elsevier Science S.A.