Effect of metal electrodes on rubrene single-crystal transistors

The authors herein have investigated the effect of the metal work function on the performance of rubrene single-crystal transistors using gold and calcium metal electrodes. The current-voltage characteristic is controlled by the metal work function, which offers the possibility of controlling the Schottky barrier height by the choice of the metal. In the process of the study of metal-rubrene contacts, the authors have realized an ambipolar transistor and a Schottky diode in an identical single-crystal device with asymmetric electrodes. These data provide direct evidence of the weak Fermi level pinning and formation of depletion layer on metal-rubrene contacts.