Observation of Au deposited self-assembled monolayers of octanethiol by scanning tunneling microscopy

SURFACE SCIENCE

卷:442

Article

Ohgi, T ; Sheng, HY ; Dong, ZC ; Nejoh, H

关键词: alkanethiols;    diffusion and migration;    epitaxy;    gold;    scanning tunneling microscopy;    self-assembly;    surface diffusion;   

DOI  :  10.1016/S0039-6028(99)00933-4

来源: Elsevier

【 摘 要 】

Au deposited self-assembled monolayers (SAMs) of octanethiol molecules have been studied by scanning tunneling microscopy. We have observed ordered structures of the molecules on both the original terraces and subsequently grown Au islands after the Au deposition. These results indicate that Au atoms penetrate through and form islands underneath the SAMs. At the initial stage of Au deposition, islands with a monatomic height grow and become larger as more Au atoms are evaporated onto the surface. The number of islands remains constant as the Au coverage increases up to approximately 0.5 ML. Above this coverage, the islands on each terrace abruptly coalesce into one network structure. The second layer starts to form after coalescence, before the first layer fully covers the surface. This unique island growth is not seen in the normal homoepitaxial growth of Au on Au(111), and is presumably attributed to both the high nucleation density of deposited atoms caused by SAMs and the relatively high diffusion of adatoms along island step edges. (C) 1999 Published by Elsevier Science B.V. All rights reserved.

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