AVS 50th International Symposium
    Processing at the Nanoscale Thursday Sessions
       Session PN-ThA

Paper PN-ThA1
AFM-Based Lithography and Conductive Probe Measurements with Substituted Oligo(phenylene ethynylene) Molecular Wires on Au(111)

Thursday, November 6, 2003, 2:00 pm, Room 317

Session: Molecular Monolayers
Presenter: J.C. Garno, National Institute of Standards and Technology
Authors: J.C. Garno, National Institute of Standards and Technology
J.D. Batteas, National Institute of Standards and Technology
Correspondent: Click to Email
AFM-based lithography is combined with conductive probe AFM (CP-AFM) measurements to characterize the surface structure and conductive properties of designed test platforms comprised of substituted oligo(phenylene ethynylene) molecules within a matrix of alkanethiol self-assembled monolayers (SAMs). Oligo(phenylene ethynylene)s on Au(111) are excellent candidates for molecular electronics, due to their rigid, planar structure and pi-conjugated backbone. When substituents are attached to oligo(phenylene ethynylene)s, electronic properties such as negative differential resistance and molecular scale switching behavior have been reported. Nanopatterned test platforms may provide a means to obtain a highly reproducible contact area in which the alkanethiol matrix of the test platforms serves as a boundary and provides an insulating frame of reference in the areas surrounding test elements. In CP-AFM, the probe is placed directly on the surface of the fabricated nanostructure, at a certain applied force. The alkanethiol matrix may be used as an internal calibration for CP-AFM measurements, with direct side-by-side comparisons of the alkanethiol matrix versus test molecule. Nanopatterns generated using AFM-based nanofabrication furnish local measurements of the thickness of molecular wire SAMs, using matrix alkanethiols as a height reference. By systematically varying certain parameters, such as the size, composition, geometry, and arrangement of test elements, we anticipate that changes can be correlated with measured conductivity, to shed light on predicting how electrical properties vary with molecular structure. Useful design parameters for molecular electronics which could be gained from this approach include the critical geometry and size thresholds for functional device elements, differences in electrical conductivity of materials, and the structural motifs best suited for devices.