Electrical characterization of metal/pentacene contacts

We report on the results of electrical characterization experiments on metal/ pentacene contacts. The metals explored were gold, silver, and platinum. Two kinds of devices were fabricated and tested: symmetric metal/pentacene/metal structures and nonsymmetric metal/pentacene/indium-tin-oxide structures. The rectification ratio of the latter devices was found to depend strongly on the metal and ranged between 2 and 10(3) for applied voltages of +/- 1 V. Schottky barrier heights were extracted from the reverse current activation energy measurements over the temperature range of similar to 240-340 K. Numerical device modeling using the experimentally determined Schottky barrier heights yielded results that are consistent with the experimental current-voltage characteristics, and indicated the presence of a non-negligible (trapped) positive space charge in the pentacene films. (c) 2007 American Institute of Physics.