Transport Properties of a MoS sub(2)/WSe sub(2) Heterojunction Transistor and Its Potential for Application

This paper studies band-to-band tunneling in the transverse and lateral directions of van der Waals MoS sub(2)/WSe sub(2) heterojunctions. We observe room-temperature negative differential resistance (NDR) in a heterojunction diode comprised of few-layer WSe sub(2) stacked on multilayer MoS sub(2). The presence of NDR is attributed to the lateral band-to-band tunneling at the edge of the MoS sub(2)/WSe sub(2) heterojunction. The backward tunneling diode shows an average conductance slope of 75 mV/dec with a high curvature coefficient of 62 V super(-1). Associated with the tunnel-diode characteristics, a positive-to-negative transconductance in the MoS sub(2)/WSe sub(2) heterojunction transistors is observed. The transition is induced by strong interlayer coupling between the films, which results in charge density and energy-band modulation. The sign change in transconductance is particularly useful for multivalued logic (MVL) circuits, and we therefore propose and demonstrate for the first time an MVL-inverter that shows three levels of logic using one pair of p-type transistors. Keywords: Transition metal dichalcogenide; heterojunction transistor; band-to-band tunneling; negative differential resistance; multivalued logic