Field-effect transistor with thin films of pentacene has been fabricated with Au electrodes modified by 1-hexadecanethiol (C16H33SH), and the hole-injection barriers have been determined from the temperature dependence of output properties on the basis of the thermionic emission model for double Schottky barriers. The large tunneling barriers are formed by the insulating C16H33SH at the interfaces between the Au electrodes and pentacene thin films. (c) 2007 American Institute of Physics.