STRUCTURAL DEFECTS OF THE SI(111)ROOT-X-ROOT-3-B SURFACE STUDIED BY SCANNING-TUNNELING-MICROSCOPY

Scanning tunneling microscopy has been used to study structural defect s of the Si(111)root 3x root 3-B surface phase formed by high-temperat ure annealing of the B-doped Si samples. The typical defects have been found to be (a)occupation of a B position by a Si atom, (b) Si adatom s in H-3 positions, (c) regions of other reconstructions (2 x 2 and c( 4 x 2)), (d) two types of ring-like six-adatom defects and (e) deep ho les (vacancies). The atomic structure of the defects has been clarifie d. The effect of the different heat treatments and B coverage on the d ensity of defects has been elucidated.