| AVS 54th International Symposium | |
| Surface Science | Thursday Sessions |
| Session SS-ThP |
| Session: | Surface Science Poster Session |
| Presenter: | Y. Qi, University of California, Berkeley |
| Authors: | Y. Qi, University of California, Berkeley B. Hendriksen, Lawrence Berkeley National Laboratory V. Navarro, Lawrence Berkeley National Laboratory D. Esteban, Lawrence Berkeley National Laboratory J.Y. Park, Lawrence Berkeley National Laboratory I. Ratera, Lawrence Berkeley National Laboratory J. Klopp, Lawrence Berkeley National Laboratory C. Mauldin, University of California, Berkeley C. Edder, Lawrence Berkeley National Laboratory J. Frechet, University of California, Berkeley M. Salmeron, Lawrence Berkeley National Laboratory |
| Correspondent: | Click to Email |
The incorporation of molecules in electronic devices is promising for technological applications and a new direction in fundamental research. The structural, mechanical and electronic properties of manolayers of two molecules containing pi-systems have been studied with conducting probe atomic force microscope (CP-AFM), X-ray photoemission spectroscopy (XPS) and near edge X-ray fine structure spectroscopy (NEXAFS). One is w-(trans-4-stilbene)alkylthiol, and the other is decyl-pentathiophenyl butyric acid. We found that the w-(trans-4-stilbene)alkylthiol molecules self-assemble on Au (111) with the thiol group covalently bond to Au surfaces as confirmed by X-ray photoemission spectroscopy. The molecular film undergoes a slow structural change from a tilted to a more upright geometry, a process that can be accelerated by thermal annealing. In all cases w-(trans-4-stilbene)alkylthiol molecules show poor electrical conductivity in the vertical direction. Molecular monolayers of decyl-pentathiophenyl butyric acid were deposited on heavily doped Si (100) by the Langmuir Blodgett technique. The orientation of the molecules has been studied by NEXAFS. Current versus voltage measurements and conductivity mapping reveal a higher conductivity than that of w-(trans-4-stilbene)alkylthiol self-assembled monolayers. The friction and the conductivity were observed to strongly depend on the molecular arrangement.