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Proceedings Paper

STM and XPS investigation of molecular electronics bonded to substrates
Author(s): Moses W. Haimbodi; Adam M. Rawlett; Conan Wieland; Korhan Demirkan; Anshuman Anshuman; Robert L. Opila
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Paper Abstract

The interest in organic based molecular electronics has spurred new attempts to control electronic properties of single molecules. We are approaching this goal by looking at two systems: conductivity of thiol-based self-assembled monolayers (SAMs) and phenylene ethynylene oligomers deposited on Au surfaces, and viability of covalently tethering molecules to Si substrates. In both cases, the molecules have extended conjugated π-systems. In this report, we will present results of scanning tunneling microscope investigation of oligo (phenylene ethynylene)(OPE) inserted between molecules of monolayers of dodecanethiol self-assembled on Au(111)/mica substrates, and XPS results of phenylacetylene and 1-bromo-2-ethynylbenzene attached to Si (111) substrates. The investigated OPE are both unsubstituted and substituted with a single -NO2 group on the central ring [4,4’-(diethynylphenyl)-2’-nitro-1-benzenethiolate] inserted in the defects of dodecanethiol SAMs. The conductivity of those systems attached to Au varies as a function of time. Our results show no particular dependence of this variable conductivity on substitution and structure of the monolayer. In addition, preliminary experiments have been performed attaching phenylacetylene and 1-bromo-2-ethynylenebenzene to variously doped hydrogen terminated Si(111) surfaces in-situ using UV photon assisted propagation reactions. The object is to determine how the conductivity through the molecules depends upon the relative alignment of the substrate conduction and valence bands and the molecular bonding and antibonding levels.

Paper Details

Date Published: 19 January 2005
PDF: 8 pages
Proc. SPIE 5592, Nanofabrication: Technologies, Devices, and Applications, (19 January 2005); doi: 10.1117/12.571524
Show Author Affiliations
Moses W. Haimbodi, Univ. of Delaware (United States)
Adam M. Rawlett, Army Research Lab. (United States)
Conan Wieland, Univ. of Delaware (United States)
Korhan Demirkan, Univ. of Delaware (United States)
Anshuman Anshuman, Univ. of Delaware (United States)
Robert L. Opila, Univ. of Delaware (United States)

Published in SPIE Proceedings Vol. 5592:
Nanofabrication: Technologies, Devices, and Applications
Warren Y-C. Lai; Stanley Pau; O. Daniel Lopez, Editor(s)

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