Contact resistance variation in top-contact organic thin-film transistors with the deposition rate of Au source/drain electrodes

We investigated the effect of the deposition rate of Au source/drain electrodes on the contact resistance of the top-contact organic thin-film transistors (OTFTs). For the formation of source/drain contacts, Au was thermally deposited at the different rates of 0.5, 1.0, 5.0, and 13.0 angstrom/s. With increasing the Au deposition rate, the contact resistance extracted at the gate voltage of -30 V could be reduced from 14 x 10(6) to 2.4 x 10(6) Omega, resulting in the characteristic improvements of the top-contact OTFT. It is also found that the contact resistance significantly affects the off-state currents of the device having the short channel length of 10 pm. The control of the deposition rate of source/drain electrodes is suggested to optimize the contact properties of the top-contact OTFTs as well as the device performance. (C) 2010 Elsevier B.V. All rights reserved.