Quantum tunneling in two-dimensional van der Waals heterostructures and devices

Quantum tunneling with band-structure engineering has been feasibly developed for many applications in electrical, optoelectrical, and magnetic devices. It relies on layer-by-layer design and fabrication, which is an interdisciplinary research field covering material science and technology. Ever since the discovery of two-dimensional (2D) layered materials, tunneling devices based on 2D van der Waals (vdW) heterostructures have been extensively studied as potential next-generation devices. 2D materials are thin at the atomic scale and extremely flat without surface dangling bonds. Because of these unique characteristics, 2D vdW heterostructures offer superior tunneling performance that reaches the benchmark of traditional Si technology and possess additional ability to scale down device size. Here, we comprehensively review quantum tunneling in 2D vdW heterostructures, in addition to their unique mechanisms and applications. Moreover, we analyze the possibilities and challenges currently faced by 2D tunneling devices and provide a perspective on their exploitation for advanced future applications. The investigation of technology- and performance-control of 2D tunneling devices is at their beginning stages; however, these devices should emerge as competitive candidates for realizing low-power supply, fast-speed capability, and high-frequency operating devices.