Control of stability in a dual-gate transistor based on WSe2/MoS2 van der Waals heterostructures

Two-dimensional semiconductor exhibits various advantages in building next-generation field-effect transistor based on van der Waals materials. However, due to the interaction between charge carriers in the semiconductor and the defects in the adjacent insulator, the trapped charges are generated and can cause substantial hysteresis and drifts of threshold voltage. This situation impedes the stable operation of the circuit. Much previous work has focused on enhancing device stability by carrier-defect energy decoupling. However, research on the stability of ambipolar transistors remains insufficient. In this work, we utilize the unique ambipolar property of WSe2, whose transport behavior can be switched between a p-type and n-type semiconductor simply by applying an external electric field. We demonstrate the control of stability in a WSe2/MoS2 dual-channel transistor with a double-gate device geometry. The transfer characteristics monitored by the hysteresis width is proved to be tuned by applying a top-gate voltage. The charge trapping at the interface between WSe2 and the oxide layer is found to be controlled by tuning the Fermi level of the WSe2 layer. This mechanism accounts for the controllable stability of the device. Our results provide a promising route toward constructing an energy-efficient two-dimensional transistor with controllable stability.