Formation and atomic structure of self-assembled Dy silicide clusters on the Si(111)7×7 surface

• Published in: Surface science 2013-03, Vol.609, p.215-220
• Main Authors: Franz, M., Appelfeller, S., Rychetsky, M., Dähne, M.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Nanoclusters; Physics; Rare earths; Scanning tunneling microscopy; Self-assembly; Silicides; Silicon
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2012.12.010

The formation and atomic structure of self-assembled Dy silicide clusters on the Si(111)7×7 surface are studied using scanning tunneling microscopy. We used Dy coverages in the range from 0.04ML to 0.2ML, substrate temperatures from room temperature to 500°C, and two different annealing procedures, reactive deposition epitaxy and solid phase epitaxy, to investigate the growth behavior of these clusters. Depending on the preparation conditions we found the self-assembly of different cluster types. Two main types of Dy silicide clusters occurring frequently were identified: off-center clusters that form close to an edge of the half unit cell and centered clusters that appear as triangles centered within the half unit cell. Both cluster types show a strong preference for the faulted half unit cell of the 7×7 reconstruction. By carefully analyzing the STM images we were able to identify the atomic structure of the off-center Dy silicide clusters and to propose a structure model for the centered Dy silicide clusters, both consisting of six Dy atoms and three Si atoms. ► The self-assembly of Dy silicide clusters on Si(111)7×7 was investigated using STM. ► Different cluster types form depending on the preparation conditions. ► Two main cluster types were identified and studied in detail. ► The atomic structure of these two cluster types is proposed.