IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Science Monday Sessions
       Session SS2-MoP

Paper SS2-MoP3
Initial Growth of Ag Islands on Ge(001) Surface at Low Temperature

Monday, October 29, 2001, 5:30 pm, Room 134/135

Session: Surfaces and Interfaces Poster Session
Presenter: Y. Naitoh, ISSP, University of Tokyo, Japan
Authors: Y. Naitoh, ISSP, University of Tokyo, Japan
K. Nakatsuji, ISSP, University of Tokyo, Japan
F. Komori, ISSP, University of Tokyo, Japan
K. Seino, Tottori University, Japan
A. Ishii, Tottori University, Japan
Correspondent: Click to Email
The Ag on Ge(001) surface has been an interesting issue for the last decade since suddenly increase of the surface electronic conductivity at 2K was reported.@footnote 1@ It is suggested the interface between Ag and Ge has peculiar electronic state because neither Ag nor Ge bulk have superconductivity. In the latest STM observation@footnote 2@ showed that mono-atomic-layer (ML) thick Ag islands parallel to the dimer-row of the Ge(001) surface and Ag chains along the dimmer direction are formed at the initial stage of the Ag deposition on a 90 K substrate followed by annealing to room temperature (RT). In the present paper, we show the Ag adsorbed sites on Ge(001) surface by STM without annealing to RT. The STM experiments were performed in an ultra high vacuum (below 1x10@super -8@Pa) system. The surface of a Ge(001) crystal, which was cut from n-type Ge(001), was cleaned by several cycles of Ar@super +@ bombardment and annealing. Ag was deposited onto the clean Ge surface at 90K with the rate of 1 ML/min, and then the substrate was moved to the STM unit as keeping the low temperature. Bright dots, which indicate Ag atoms, were observed between the Ge dimer rows. It was found some dots were arranged to form chains along both the dimer row and the dimer direction having intervals of 2a@sub Ge@ (a@sub Ge@=0.4nm) and islands with 2a@sub Ge@ width elongating along the dimer row. As annealing the substrate to RT bright dots disappeared and the conventional Ag chains and islands were found to be formed. This shows Ag sites on Ge(001) surface without annealing to RT are quasi-stable. These were compared with the stable site of Ag on the surface given by the first-principles calculation. @FootnoteText@ @footnote 1@ M. J. Burns et al., Solid State Comm. 51, 865 (1984) @footnote 2@ F. Komori et al., Surf. Sci. 438, 1234 (1999).