Dresden 2006 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 21: SYMPOSIUM Functional Organic Thin Films II
CPP 21.6: Vortrag
Donnerstag, 30. März 2006, 15:45–16:00, ZEU Lich
The realization of a defect-free pentacene based organic semiconductor diode: dominance of n-conduction — •Carsten Busse1, Lars Ruppel1, Alexander Birkner1, Gregor Witte1, Christof Wöll1, and Gernot Paasch2 — 1Lehrstuhl für Physikalische Chemie I, Ruhr-Universität Bochum, 44780 Bochum, Germany — 2Leibnitz Institute for Solid State and Materials Research IFW Dresden, 01171 Dresden, Germany
We have fabricated an organic diode based on a defect-free organic semiconductor with two tunneling electrodes: Pentacene was deposited on an Au(111) surface, which was modified by an insulating self-assembled monolayer (SAM) of alkanethiols. High-resolution STM-data reveal the formation of virtually perfect pentacene islands. Using the tip of an STM and the Au-substrate as a pair of electrodes, we investigated the transport characteristics of this organic diode as a function of thickness of the pentacene layers and of temperature. In addition, the interface dipole at the pentacene / Au+SAM electrode was varied by changing the endgroups of the alkanethiols (-CH3, -CF3, -COOH). The results demonstrate that the transport properties are controlled by the built-up of a region with space-charge limited current just below the tip. The temperature dependence indicates that at room temperature and below the current in this model device is due to band-like transport. In addition, n-type behavior is seen in contrast to the commonly observed p-type behavior for polycrystalline pentacene.