Structural and electronic properties of clean and defected Si-SiC[001] surfaces

We have studied the reconstructions and electronic properties of both clean and defected Si-terminated [001] surfaces of cubic SiC, by performing first principles computations within density functional theory. We find that the unstrained bulk exhibits a stable p(2/spl times/1) reconstruction, whereas a bulk under tensile stress shows a c(4/spl times/2) reconstruction. Furthermore our calculations indicate that ad-dimers are common defects on the Si-terminated SiC[001] surface. These results permit the interpretation of recent STM and X-ray-photoemission experimental data.