Sub 10 nm conjugated polymer transistors for chemical sensing

Chemical sensing responses of polythiophene transistors were investigated with various channel lengths down to sub 10 nm. To eliminate undesirable spreading currents, a novel four-terminal geometry was employed which ensures that the sensor active area is truly nanoscale. For the same analyte-semiconductor combination, the nanoscale devices exhibited drastically different responses compared with larger scale devices. In general, the nanoscale transistors experienced an increase in drain current upon exposure to analytes such as 1-pentanol and vanillin, whereas the larger devices showed a decrease. The chemical sensing mechanisms in both microscale and nanoscale transistors are briefly discussed.