Transport Properties of a MoS₂/WSe₂ Heterojunction Transistor and Its Potential for Application

TLDR

The study investigates band‑to‑band tunneling in both transverse and lateral directions of MoS₂/WSe₂ van der Waals heterojunctions. Strong interlayer coupling between MoS₂ and WSe₂ layers induces charge‑density and band‑modulation effects that drive the observed tunneling behavior. At room temperature the heterojunction diode exhibits negative differential resistance with an average conductance slope of 75 mV/dec and a curvature coefficient of 62 V⁻¹, while the induced transconductance reversal enables a multivalued logic inverter that achieves three distinct logic levels using a single pair of p‑type transistors.

Abstract

This paper studies band-to-band tunneling in the transverse and lateral directions of van der Waals MoS2/WSe2 heterojunctions. We observe room-temperature negative differential resistance (NDR) in a heterojunction diode comprised of few-layer WSe2 stacked on multilayer MoS2. The presence of NDR is attributed to the lateral band-to-band tunneling at the edge of the MoS2/WSe2 heterojunction. The backward tunneling diode shows an average conductance slope of 75 mV/dec with a high curvature coefficient of 62 V–1. Associated with the tunnel-diode characteristics, a positive-to-negative transconductance in the MoS2/WSe2 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.