Will We See Gigahertz Organic Transistors?

Despite the many advances in the materials and technology of organic transistors, the highest transit frequency reported for organic transistors has not been improved for more than half a decade and remains far below 1 GHz. One reason is that most contributions to the field have traditionally focused on parameters that have little or no impact on the high-frequency performance of organic transistors. By analyzing the fundamental equations for the transit frequency and the effective (or apparent) carrier mobility, the requirements under which organic transistors can be expected to show a transit frequency of 1 GHz are reiterated. Not surprisingly, it is found that the critical parameter in this quest is not the charge-carrier mobility in the organic semiconductor layer, but the contact resistance, along with the channel length and the parasitic gate-to-contact overlaps.