Reduced contact resistances in organic transistors with secondary gates on source and drain electrodes

Secondary-gate electrodes under source and drain electrodes are introduced in organic thin-film transistors to reduce carrier-injection barriers into air-stable organic semiconductors. The additional gate electrodes buried in the gate insulators form carrier-rich regions in the vicinity of the source and drain electrodes with the application of sufficiently high local electric fields. Fabricating the structure with dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene, known for its excellent air stability, the contact resistance is drastically reduced especially at low gate voltages in the main channel. The result demonstrates carrier injection from the same material realizing a minimized potential barrier in the absence of interfacial trap levels for metal-to-semiconductor junctions. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3231927]