Scanning tunneling microscopy investigation of the C-terminated β-SiC(100) c(2 x 2) surface reconstruction:: dimer orientation, defects and antiphase boundaries

We investigate beta-SiC(100) c(2 x 2) surface reconstruction by atom-resolved scanning tunneling microscopy (filled and empty electronic states). The results indicate that, contrary to previous knowledge, the C=C triple-bond dimers that compose this surface are asymmetric and all tilted in the same direction (i.e. not anticorrelated), which suggests a compressive stress along the dimer direction. We also identify two specific defects: double dimer lines that are at the origin of antiphase boundaries, and missing dimers. In the latter case, the two nearest dimer neighbors along the dimer row are found to undergo a significant charge redistribution, leading to one of them being tilted in the opposite direction. (C) 2000 Elsevier Science B.V. All rights reserved.