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SYOF: Organische Festkörper

SYOF 1: Organic Semiconductor Devices

SYOF 1.4: Talk

Tuesday, March 27, 2001, 10:40–10:55, S6

Organic modified GaAs(100) Schottky contacts — •Th. Lindner, S. Park, T.U. Kampen, and D.R.T. Zahn — Institut für Physik, TU Chemnitz, D-09107 Chemnitz, Germany

We investigated the current-voltage-(I/V) and capacitance-voltage-characteristics (C/V) of Ag/n-GaAs(100) diodes with organic interlayers of various film thickness. The organic semiconductor 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) serves as the organic film. The I/V-characteristics can be fitted using a model including thermionic emission and space-charge-limited currents. At low current densities thermionic emission dominates, while at high current densities space-charge effects in the organic film govern the charge transport. From the I/V-characteristics an effective barrier height is determined which decreases with increasing organic film thickness and is constant for thicknesses above 100 monolayers. The C/V-measurements, on the other hand, show that the space charge region in the GaAs, i.e. the band bending, is not affected by the PTCDA. The physical origin of the difference in barrier heights determined by I/V and C/V-measurements is discussed.