Energy-Efficient Tunneling Field-Effect Transistors for Low-Power Device Applications: Challenges and Opportunities.

Conventional field-effect transistors (FETs) have long been considered a fundamental electronic component for a diverse range of devices. However, nanoelectronic circuits based on FETs are not energy efficient because they require a large supply voltage for switching applications. To reduce the supply voltage in standard FETs, which is hampered by the 60 mV/decade limit established by the subthreshold swing (SS), a new class of FETs have been designed, tunnel FETs (TFETs). A TFET utilizes charge-carrier transportation in device channels using quantum mechanical based band-to-band tunneling despite of conventional thermal injection. The TFETs fabricated with thin semiconducting film or nanowires can attain a 100-fold power drop compared to complementary metal-oxide-semiconductor (CMOS) transistors. As a result, the use of TFETs and CMOS technology together could ameliorate integrated circuits for low-power devices. The discovery of two-dimensional (2D) materials with a diverse range of electronic properties has also opened new gateways for condensed matter physics, nanotechnology, and material science, thus potentially improving TFET-based devices in terms of device design and performance. In this review, state-of-art TFET devices exhibiting different semiconducting channels and geometries are comprehensively reviewed followed by a brief discussion of the challenges that remain for the development of high-performance devices. Lastly, future prospects are presented for the improvement of device design and the working efficiency of TFETs.