AVS 46th International Symposium
    Organic Electronic Materials Topical Conference Monday Sessions
       Session OE+EM+FP-MoA

Paper OE+EM+FP-MoA3
Resistance of Individual Molecular Semiconductor Grains Measured by Conducting Probe Atomic Force Microscopy

Monday, October 25, 1999, 2:40 pm, Room 616/617

Session: Transport and Nanostructures in Organic Films
Presenter: T.W. Kelley, University of Minnesota
Authors: T.W. Kelley, University of Minnesota
C.D. Frisbie, University of Minnesota
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Continued interest in organic electronics has underscored the need for better understanding of transport mechanisms in polycrystalline films of organic semiconductors. We are employing conducting probe atomic force microscopy (CP-AFM) to measure the electrical resistances associated with individual grains and grain boundaries in thin films of @alpha@-sexithiophene (6T). These measurements focus on single 6T grains that are several microns in length and width and 1 - 6 molecular layers (2-14 nm) in thickness. The 6T grains are vacuum deposited onto insulating substrates with lithographically patterned gold electrodes. A Au-coated AFM probe is used to image each grain, including any crystal defects, and to subsequently make point-contact electrical measurements at particular positions on the grain. Current-voltage (I-V) curves are recorded at each position as a function of probe-electrode separation. From these data, we estimate tip-grain contact resistance and conductivity of each grain. In general, we show that CP-AFM is a powerful approach to exploring the effects of microstructure on conductivity in organic semiconductor films.