AVS 47th International Symposium
    Surface Science Tuesday Sessions
       Session SS2+NS+BI+EL-TuM

Paper SS2+NS+BI+EL-TuM4
Self-Assembled Monolayers of Terphenyl Derivatized Thiols; Adsorption, Insertion Process and Electrical Conduction

Tuesday, October 3, 2000, 9:20 am, Room 209

Session: Self-Assembled Monolayers
Presenter: T. Ishida, JRCAT-NAIR and PRESTO-JST, Japan
Authors: T. Ishida, JRCAT-NAIR and PRESTO-JST, Japan
W. Mizutani, JRCAT-NAIR, Japan
N. Choi, JRCAT-ATP, Japan
H. Tokumoto, JRCAT-NAIR, Japan
Correspondent: Click to Email
The investigation of SAMs made from conjugated molecules is highly activated from a viewpoint of molecular electronics as well as stable SAM formation. In the present study, we have investigated an insertion process of conjugated molecules, terphenylthiol (TP0), terphenyl methanethiol (TP1), terphenyl propanethiol (TP3), into nonanethiol self-assembled monolayers (SAMs) on Au(111) by STM. STM observation revealed that the insertion process is dependent on the molecular length of conjugated molecules. At the initial stage of insertion, replaced area of TP1 is larger than those of TP0 and TP3. However, when the immersing time is more than 12h, the replaced area of TP3 is larger than those of TP0 and TP1. The insertion process is likely to be determined by the solubility of the conjugated molecules and thermal dynamics. The single molecular resistance were increased with the number of the methylene groups, and obtained about 20G-ohm (TP0), 40 G-ohm (TP1) and 66 G-ohm (TP3). The vertical conduction of the conjugated molecular domains of TP1 and TP3 depended on their lateral sizes, while strong dependence was not observed in the case of TP0, suggesting that methylene group is necessary between the sulfur and aromatic rings to increase the vertical conduction of molecular domain.