Regensburg 2007 – scientific programme

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SYOE: Symposium Organic Thin Film Electronics: From Molecular Contacts to Devices

SYOE 8: Poster Session SYOE

SYOE 8.3: Poster

Tuesday, March 27, 2007, 18:00–20:00, Poster B

Electrostatic trapping of individual polymer molecules between microfabricated electrodes — •Aleksandar Ivanov, Arne Hoppe, Jürgen Fritz, and Veit Wagner — International University Bremen, D-28759, Bremen, Germany (Jacobs University Bremen, as of Spring 2007)

Reliable deposition of single molecules between electrodes is a crucial step in the fabrication of molecular electronic devices. We report on an approach for deposition and electrostatic trapping of conducting polymers in solution followed by electrical measurements. Here we used regioregular poly(3-hexylthiophene) (P3HT), a polymer with an average chain length of 250 nm. Microfabricated interdigitated Au electrodes on silicon oxide (channel length of 200 nm, 100 nm) fabricated by e-beam lithography are dipped in a highly diluted polymer solution. During dipping a moderate DC voltage (0 ... 3 V) was applied. The dipping was followed by electrical measurements performed in air. Low current levels (< 50 pA) were recorded without an applied field during dipping. A significant increase of the current across the electrodes up to several 100 nA upon application of external DC fields in solution revealed the trapping of a low number of conducting polymers. Surprisingly the current level kept changing for several minutes before it stabilized. These changes depended strongly on the polarity of the applied voltage during dipping and are interpreted as rearrangement of polymer chains under applied voltage. The effect of field strength and polarity on trapping efficiency as well as the dependence of current on the number of molecules and channel length will be discussed.