Nanoscale polymer field-effect transistors

Regioregular poly thiophene has been successfully used in large-area FET'S on account of its excellent self-assembly properties. We describe the characteristics of regioregular polythiophene FET's with various geometry configurations and channel lengths down to 4 nm. The effects of shrinking channel length were investigated for 100 nm 40 nm channel length FET's with source and drain patterned by a special design of large W/L ratio. Nanometer scale gaps down to 4 nm were formed by electrostatic trapping followed by electro migration processes. The impact of gap geometry was discussed. To suppress the spreading current effects, we employed a pair of guarding electrodes near the two sides of the channel which were kept at the same potential as the drain. The true responses of these nanometer scale FET's exhibit pronounced short-channel effects due to the thick gate insulator used (100 nm) relative to the channel lengths. Our home-developed numerical model simulated the behavior of a 5 nm channel FET and reasonable agreement with the experimental data was obtained.