REGULAR DEFECTS ON THE SI(111)-(7X7) SURFACE STUDIED BY SCANNING-TUNNELING-MICROSCOPY

Two kinds of regular defects have been observed in our experiments. On e kind is caused by losing or inserting adatom rows between two domain boundaries. The other is caused by losing or inserting adatom rows be tween two domain boundaries, while one domain shifts relative to the o ther along the short diagonal of the (7 x 7) unit cell. The former usu ally has simple shapes and a period of 7a, while the latter has comple x shapes and a period of 14a, where a is the length of the primitive l attice vector of the Si(111) surface. The shapes of the defects are de cided by three factors: (i) the nucleation sires of the two domains, ( ii) the growth rates of the two domains, and (iii) the strong interact ion between the dimers and adatoms located at the domain boundaries. ( C) 1998 Elsevier Science B.V. All rights reserved.