Steep Slope Threshold Switching Field-Effect Transistors Based on 2D Heterostructure*

In dealing with the increasing power dissipation of electronic systems with increasing integration density, field-effect transistor (FET) with steep switching slope that overcomes the thermionic limit is vital to achieve low-power operations. Here, we report two types of threshold switching (TS) FETs based on 2D van der Waals heterostructures by virtue of the abrupt resistive switching of the hexagonal boron nitride (hBN) TS device. The common hBN dielectric layer functions as the switching medium for the TS device and the gate dielectric for the 2D FET enabling seamless integration of the hBN TS device and baseline 2D FET. TSFET in source configuration by connecting the TS device to the source terminal of the 2D FET offers an ultralow subthreshold swing (SS) of 2.2 mV/dec across six decades of drain current at room temperature and suppressed leakage current. In addition, the threshold voltage can be modulated by changing the drain voltage due to voltage division between the FET and TS device. TSFET in gate configuration by connecting the TS device to the gate terminal of the 2D FET also exhibits steep switching slope with ultralow SS of 3.5 mV/dec. The proposed compact device structures integrating 2D FET and TS device provide a potential approach of monolithic integration toward next-generation low-power electronics.