Flexible nanoscale organic thin-film transistors

The transit frequency of organic thin-film transistors is limited mainly by the contact resistance and the critical dimensions (channel length, gate-to-contact overlaps). Decreasing the contact resistance to within three orders of magnitude of the theoretical limit has led to flexible organic TFTs with a transit frequency of 21 MHz at 3 V for critical dimensions of about 1 µm. Using electron-beam lithography, flexible organic TFTs with channel lengths and gate-to-contact overlaps well below 1 µm were recently demonstrated that display reasonable static characteristics, but suffer from a larger contact resistance that limits the transit frequency to 36 MHz for p-channel and 8 MHz for n-channel TFTs (at 3 V). One of the challenges in improving the transit frequency of flexible organic TFTs to 100 MHz and beyond will be to minimize all three TFT parameters (contact resistance, channel length, gate-to-contact overlaps) simultaneously.