Scanning tunneling microscopy on SnrSi 110/ system

Surface superstructures on SnrSi 110.system were investigated by scanning tunneling microscopy STM.. In addition to three superstructures reported previously, 4,3.= 2,2., 3,0.= 1,3.and 3,3.= 2,1., new types of superstructures such as 2,0.= 1,4.were clearly observed during transformation processes between these phases. It was found that the 4,3.= 2,2. and 3,0.= 1,3. consist of Sn trimers which arrange two- and one-dimensionally on the surface, respectively. The latter superstructure contains extra Sn atoms as monomers. The image of 3,3.= 2,1.consists of cluster protrusions that contain four or more Sn atoms arranged two-dimensionally. It was also found that the 2,0.= 1,4.superstructure consists of Sn dimer rows along thew110xdirection. Transition processes between the phases is discussed, based on the structural models proposed in the present study. q1998 Elsevier Science B.V. All rights reserved