High-mobility ambipolar transistors: Properties and function

We have fabricated high-mobility ambipolar polymer transistors and have integrated multiple transistors to demonstrate their implementation into CMOS-like logic circuitry. The performance of a selenophene-based polymer semiconductor PSeDPPBT is initially screened using standard long-channel field-effect transistors. The polymer exhibits high and balanced hole and electron mobilities of -0.5 cm2/Vs and 1.0 cm2/Vs, respectively. Next, exploiting the beneficial electronic properties of PSeDPPBT, we have fabricated ambipolar inverters, ring oscillators and logic NOR gates. Ambipolar inverters are shown to exhibit voltage inversion with proper noise margins and no voltage loss over multiple stages. The potential speed of ambipolar logic is demonstrated by the realization of ambipolar ring oscillators with unprecedented performance. The feasibility to perform logic operations is demonstrated by the fabrication of ambipolar NOR gates. The combined results, (i) no loss in voltage over multiple inverters, (ii) the unprecedented speed, and (iii) the accomplishment of a functionally complete logic operation, demonstrate the feasibility of ambipolar logic as a reliable substitute for complementary-based logic in order to realize cost-efficient electronics. © 2012 SPIE.