High-Performance Tunnel Field-Effect Transistors (TFETs) for Future Low Power Applications

Abstract

From inception, the advent of electronics industry has been propelled by advancements made in the field of integrated circuit (IC) technology. In recent years, continuous miniaturization along with batch fabrication of ICs has resulted in high performance to cost index of modern electronics system. This tremendous growth in the semiconductor IC industry has been due to the expansion in the material set, novel device design, and innovations in circuit and architectural levels. Silicon (Si)-based metal oxide semiconductor field-effect transistor (MOSFET) has been the cornerstone device for the growth of IC industry, especially for commercial electronics application. Over the years, continuous scaling of Si MOSFET has resulted in the improvement in performance to cost index. However, in the sub-nano meter technology regime, the performance of MOSFET devices has been limited due to short-channel effects (SCEs) like subthreshold conduction, drain-induced barrier lowering (DIBL), high leakage current, to mention a few. Even though innovative MOSFET designs based on gate and channel engineering like double gate (DG) MOSFET, dual material gate (DMG) MOSFET, dual material surrounding gate (DMSG), etc. structures have been reported, a major performance limitation of such devices has been the limit of scale supply voltage due to the subthreshold swing of value 60mV/decade at room temperature. A solution to continue scaling and improve the performance of ICs is an alternative device, that is, tunnel field-effect transistor (TFET). Compared to a conventional MOSFET device, a TFET has advantages in terms of high ON current (ION) to OFF current (IOFF) ratio, faster switching times, improved subthreshold swing (SS), thereby low leakage current and low power consumption. The aforementioned characteristics of TFET devices provide them an edge over conventional MOSFET for high-speed and low power applications. In addition, in recent years, in the field of healthcare, TFET-based biosensors have been extensively explored as an alternative to micro/nano electro-mechanical systems (MEMS/NEMS)-based chemical/biological sensors. Compared to MEMS/NEMS sensors, TFET-based sensors hold advantages like better integration with CMOS process flow, simplicity of fabrication, relatively mechanical stability, to mention a few. This treatise encompasses examples of TFET devices with various configurations of TFET devices for numerous applications. In this chapter, we elucidate silicon (Si), germanium (Ge), and silicon-germanium (SiGe) materials-based TFET devices. The focus of this chapter is to explain the basic device operation of TFET with mathematical models. Further, a comparison of various TFET devices considering their geometry and material selection is performed. In the later sections, various device configurations and operations of Si TFET, Ge TFET, and SiGe TFET are analyzed, followed by the design challenges and future.