Science and Technology of Tunnel Field‐Effect Transistors

Currently, the most used transistor technology is none other than metal-oxide-semiconductor field-effect transistor (MOSFET). It has been working well according to the Moore's law for nearly six decades. As the demand of miniaturization of electronic gadgets is increasing rapidly, the major concern is, will MOSFETs be able to cope with the growing demand? The answer is, No! MOSFET technology has served well, but now it needs a farewell, like every other technology used in present will become past in future. The increase in short-channel effects and subthreshold limit (Boltzmann's Tyranny) are two of the major reasons not favoring the use of this technology in near future. Tunnel field-effect transistor (TFET) has advantage of higher ON to OFF current ratio as well as steep subthreshold slope and faster switching characteristic owing to band-to-band tunneling mechanism. The focus of this chapter is on the same. The chapter starts with discussing the quantum physics approach of tunneling then short comings of MOSFET technology and finally move toward the TFET technology. Physics and working mechanism of the TFET in ON state, OFF state, and ambipolar state is explained in detailed manner. The factors influencing the performance of TFETs are discussed as well. Types of tunneling mechanism, i.e., line tunneling and point tunneling are discussed. Approaches to increase ON-state performance and reduce ambipolarity like pocket doping, Ge source, underlapping, and doping-less TFET are simulated with technology computer-aided design (TCAD) and direct current (DC) and radio frequency (RF) performance of all these configurations are discussed in detail manner. A brief comparison of some already available TFET devices and their DC and RF performance parameter's comparison is done. At last, applications of TFET devices in various fields like sensing and neuromorphic computing have been discussed.