Selenium Interface Layers Boost High Mobility and Switch Ratios in van der Waals Electronics

Achieving high mobility while minimizing off-current and static power consumption is critical for applications of two-dimensional field-effect transistors. Herein, a selenium (Se) sacrificial layer is introduced between the rhenium sulfide (ReS₂) semiconductor and source/drain electrode. With the Se layer and postannealing process, the ReS₂ transistor significantly decreases the off-state current with a substantial increase in the on-state current density. Notably, the mobility reaches 237 cm² V^-1 s^-1, which is accompanied by an extraordinary current on/off ratio of 10¹¹ at 7 K. The theoretical calculations and noise analysis show that the improvement in device performance is ascribed to the Se protective layer, which effectively shields the semiconductor from direct exposure to high-energy metal particles, reducing the Schottky barrier and the number of defect states at the interface. Finally, Se sacrificial ReS₂ transistor-based versatile logic circuits including NAND and NOR logic are executed, which can be widely applied in integrated circuits.