Ambipolar Independent Double Gate FET (Am-IDGFET) for the Design of Compact Logic Structures

Abstract

Among potential candidates to replace the CMOS transistor channel, several materials such as CNTs, GNRs, and SiNW show an interesting behavior known as “Ambipolarity.” Ambipolarity, means that n- and p-type behavior can be observed in the same device. By adding a fourth terminal to control the ambipolarity, a new category of devices has seen the light under the name of Ambipolar Independent Double Gate FETs “Am-IDGFETs.” These devices are capable of operating as either n-type or p-type switches according to their back-gate bias voltage. As a result, more options are available with no counterparts in CMOS technology. Based on Am-IDGFETs, we propose a circuit design approach to achieve compact logic structures by merging every two transistors in series structure using the in-field controllability via the back-gate of ambipolar devices. The approach is demonstrated for two logic styles: with a complementary static logic design style, it demonstrates an efficiency that can improve the compactness of logic structure by a factor of 2x, while with a dynamic logic style, a gain of 30% in terms of transistors count is achieved for a variety of application scenarios. We evaluate the performances of circuits designed from this approach in a case study focused on double gate carbon nanotube FET technology. Simulations results show that, with respect to conventional CMOS-16 nm gates and for comparable power consumption, time delay and integration density can both be improved by a factor of 2x and 2.5x, respectively. The power-delay-product is improved by 30%.