Contact effects in polymer transistors

Abstract
Polymer thin film transistors based on the polyfluorene F8T2 exhibit a nonohmic contact resistance, particularly when in the coplanar device geometry. We show how to obtain the current–voltage relation for the contact from the transistor output characteristics measured with different channel lengths. The diode-type relation is attributed to the contact injection properties of the metal Schottky barrier. No significant increase in mobility with gate or drain field is observed.