Enhancement of On-State Current in Two-Dimensional Tunnel Field-Effect Transistors by Computational Design of Interfacial van der Waals Defect States

Tunnel field-effect transistors (TFETs), as an important class of low-power devices, are usually constrained by the high resistivity of band-to-band tunneling at the electrode/channel interfaces (ECI), which results in limited on-state current. Here, we propose a strategy to enhance the on-state current of TFETs based on two-dimensional (2D) materials by designing van der Waals defect state (vdW-DS) at the ECI. Taking WTe2-based 2D TFETs as a platform, we perform first-principles calculations and quantum-transport modeling to study how various types of vdW-DS impact the device performance. We demonstrate that the on-state current of the 2D TFETs with vdW-DS can be increased by over 40-fold compared to the pristine device. The underlying mechanism can be understood as the enhanced tunneling through the ECI mediated by the vdW-DS, significantly different from the detrimental effects of defect states in conventional 2D devices. This study provides insights into improving the performance of 2D TFETs by exploiting vdW-DS via interfacial engineering.