Recent Advances in Low-Dimensional Heterojunction-Based Tunnel Field Effect Transistors

Since the continuous scaling down of the transistor channel length, extraordinary improvement is achieved in the switching speed. However, the rising leakage current degrades the power consumption seriously. In this regard, reducing supply voltage might be the most effective method. This requirement can be fulfilled well by tunnel field-effect transistors (TFETs), because carriers transport via a band-to-band tunneling manner in the TFETs. Relying on the special transport mechanism, the TFETs often require band structure modulations and steep interfaces without trap state, which are challenging for bulk materials. Therefore, these challenges have boosted TFET designs based on low-dimensional materials ranging from Si/Ge nanowires to state-of-art van der Waals heterostructures. Here, the key concepts of the currently developed TFETs are studied from the aspects of structure, material, transportation characteristic, and mechanism. According to the heterojunction bonding types, they can be divided into lateral and vertical TFETs in general. Furthermore, other related transistors based on tunneling are also included. Emerging problems and promotion methods toward these TFETs are introduced with the assistance of simulations. The main goal is to introduce the frontiers of TFET explorations and provide readers with a perspective on how to realize TFET applications in the future.