Hole mobility in organic single crystals measured by a flip-crystal field-effect technique

We report on single crystal high mobility organic field-effect transistors prepared on prefabricated substrates using a flip-crystal approach. This method minimizes crystal handling and avoids direct processing of the crystal that may degrade the field-effect transistors' electrical characteristics. A chemical treatment process for the substrate ensures a reproducible device quality. With limited purification of the starting materials, hole mobilities of 10.7, 1.3, and 1.4 cm(2)/V s have been measured on rubrene, tetracene, and pentacene single crystals, respectively. Four-terminal measurements allow for the extraction of the intrinsic transistor channel resistance and the parasitic series contact resistances. The technique employed in this study shows potential as a general method for studying charge transport in field-accumulated carrier channels near the surface of organic single crystals. (C) 2004 American Institute of Physics.