INVESTIGATION OF ATOM-RESOLVED DOMAIN BOUNDARIES ON SI(111)7X7 SURFACES BY SCANNING-TUNNELING-MICROSCOPY

Several regular defects along domain boundaries of clean Si(111)7 x 7 surfaces have been observed with scanning tunneling microscopy (STM), Combined with the dimer-adatom-stacking fault (DAS) model, their detai led atom structures are discussed. We have found three important eleme ntary factors that determine the boundary structure. The most importan t factor is the strong interaction between dimer and adatom. The next, in some cases, is the difference between faulted half and unfaulted h alf. The third factor are other metastable triangle subunit structures (e.g. 5 x 5, etc.). Under certain conditions the atoms along the doma in boundary will adjust to form such structures.