The atomic structure of the (v3 x v3)R30º reconstructed Si-terminated surface of 6H-type material was studied by using grazing-incidence X-ray diffractometry under ultra-high vacuum. A simple adatom structure, in which one Si atom per reconstructed unit cell sat in a T4 site over the top SiC bilayer, was the only one which was compatible with the data. This ruled out other models which involved Si adatoms in an H3 site, Si trimers, C adatoms or Si vacancies. The predominance of 3 bilayer steps with an A-type termination of the bulk stacking was confirmed. In addition, it was shown that variation of the preparation conditions changed the density of faulted boundaries in the reconstructed surface, but preserved a unique atomic structure within the (v3 x v3)R30º ordered domains.

(v3 x v3) R30º Reconstruction of the 6H-SiC (0001) Surface: a Simple T4 Si Adatom Structure Solved by Grazing-Incidence X-ray Diffraction. A.Coati, M.Sauvage-Simkin, Y.Garreau, R.Pinchaux, T.Argunova, K.Aïd: Physical Review B, 1999, 59[19], 12224-7