SCANNING-TUNNELING-MICROSCOPY STUDY OF SIC(0001) SURFACE RECONSTRUCTIONS

Scanning tunneling microscopy has been used to study the reconstructio ns of Si-terminated SiC(0001) surfaces observed after heat treatment a t increasing temperatures. For the root 3x root 3 reconstruction, obta ined by heating at temperatures around 950 degrees C, the images can b e explained by a model composed of 1/3 monolayer of Si or C adatoms in threefold symmetric sites on top of the outermost Si-C bilayer. For s urfaces heated above 1050 degrees C the images show growing fractions of quasiperiodic 6 x 6 and 5 x 5 reconstructions. Heating above 1250 d egrees C results in a partial graphitization of the surface which modi fies the observed 6 x 6 structure. (C) 1996 American Vacuum Society.