Optimization of the CuPc active layer thickness of static induction transistors

Static induction transistors find application in various organic devices owing to their low voltage and high current operation. Devices with layered structure consisting of Au(drain)/CuPc/Al(gate)/CuPc/ITO(source)/glass have been prepared. We report the static characteristics of devices with different edge features for the Al gate electrode. It is found that the geometry of the Al gate and the CuPc (copper phthalocyanine) active layer strongly affects the device properties. Devices of which the Al gate has been deposited with a spacer between the mask and the substrate show SIT characteristics and those without a spacer with a sharp edge for the Al gate show ohmic characteristics with no gate-effect, indicating that a thin transparent edge is necessary for the Al gate electrode to obtain SIT characteristics, resulting in the modulation of the drain current with the applied gate voltages.