Interface Characteristics between Au Electrode and Pentacene Layer in Organic Thin-film Transistors

In order to investigate interfacial characteristics between top-Au and pentacene layers, devices with the structure of bottom-Au/pentacene/top-Au were fabricated on glass substrates at various deposition rates of top-Au of about 1.0, 3.0 and 15.0 Å/s. It was observed that electrical characteristics could be improved by increasing the deposition rate of top-Au, and the highest electrical conductivity value, 1.5×10 -6 S/cm, was obtained for the device with top-Au deposited at 15.0 Å/s. Auger electron spectroscopy (AES) results showed that the atomic content of Au is substantially increased with the deposition rate of top-Au, but there is no marked difference in the depth profile of Au atoms regardless of the deposition rate of top-Au. Likewise, field-emission scanning electron microscopy (FE-SEM) images did not reveal structural defects that might cause short circuit. We also fabricated top-contact organic thin-film transistors (OTFTs) at various deposition rates of the Au layer for source/drain electrodes. As a result, the performance of the OTFTs can be modified by the deposition rate of Au. These results will be discussed.