Papers by Author: P. Soukiassian

Abstract: In order to give experimental insights on the atomic structure of the Si atomic wires developing on the β-SiC(100) surface, we use synchrotron radiation-based x-ray diffraction at grazing incidence to study a network of such atomic lines in a 5x2 surface array. Our results lead to an accurate surface and sub-surface structure determination evidencing a structure in agreement with a two adlayer symmetric dimer reconstruction. This atomic structure is significantly different from the 3x2 surface structure, giving new insights on the Si atomic lines stability.

Abstract: Atomic structure and morphology of 6H-SiC(0001) and 3C-SiC(100) surfaces are studied by scanning tunneling microscopy (STM), synchrotron radiation-based !-spot x-ray photoemission spectroscopy (!-spot XPS) and low energy electron microscopy (LEEM). STM shows very high quality Si-rich 6H-SiC(0001) 3x3 surfaces with less than 2% of atomic defects. Si removal upon annealing leads to atomic crack defects formation with a novel 2"3x2"3-R30° reconstruction coexisting with few 3x3 domains having no crack, suggesting important stress relief during the phase transition. LEEM also shows cracks formation on cubic 3C-SiC(100) surfaces and gives insights about surface morphology with large faceting and mesa (!m) formation. These defect fractures developing upon Si removal are likely to be also generated during initial oxidation since the initial oxygen interaction tends to relieve surface strain on SiC in contrast to Si surfaces. These atomic crack defects could be related to the interface electronic states recurrent at SiO2/SiC interfaces.