SCANNING-TUNNELING-MICROSCOPE OBSERVATION OF 2X1 STRUCTURE ON A HOMOEPITAXIALLY GROWN SI(111) SURFACE

We have used scanning tunneling microscopy to study molecular-beam epitaxial growth on Si(111)7 X 7 surface. On the homoepitaxially grown surface at 500-degrees-C, we find the small domains of non-DAS (dimer adatom stacking fault) rowlike ordered structures, the periodic rows of which run along the [011BAR] and [110BAR] directions. The atomic configuration of these structures seems to be consistent with Pandey's pi-bonded chain model for Si(111)2 X 1 structure. We discuss two kinds of pi-bonded chains, and the boundaries along the atomic rows between the 2 X 1 and DAS domains.