Pentacene organic field-effect transistors with doped electrode-semiconductor contacts

The contact resistance in pentacene organic field-effect transistors (OFETs) is found to be significantly reduced by selectively doping the organic semiconductor region beneath the source/drain electrodes. A 10 nm co-evaporated (1: 1 ratio) layer of molybdenum tris-[1,2-bis(trifluoromethyl) ethane-1,2-dithiolene] and pentacene was deposited under the metal electrodes for this purpose. The width-normalized contact resistance (varying channel lengths of 25-200 mu m used for the study) in contact-doped devices was lowered significantly (0.5 k Omega-cm) in comparison to reference devices (3.4 k Omega-cm) in the accumulation regime (V-GS = similar to 30 V). Doping of the contacts did not affect the stability of the devices under continuous bias stress significantly. (C) 2010 Elsevier B. V. All rights reserved.