High-temperature negative differential resistance in tungsten diselenide multilayers without heterojunctions

Abstract

Various exotic functional electronics devices have been proposed to address the limitations of conventional complementary metal oxide semiconductor devices. Among them, negative differential resistance (NDR) devices have been integrated with heavily doped n-type and p-type channel layers to form heterojunctions. However, undesired interfacial defects are unavoidable during heterojunction formation, and the selection of appropriate materials for type-III gap formation is constrained by the requirement for a desirable band alignment. Herein, we report the presence of NDR in WSe₂ multilayers without heterojunctions under high electrostatic drain and gate bias conditions of up to a temperature of 450 K. The peak-to-valley current ratio (PVCR) is approximately 1.2 at room temperature indicating enhanced thermal perturbation and carrier–carrier scattering. Despite an increase in the activation energy induced by enhanced drain bias in deep metallic regimes, the observed NDR can be primarily attributed to the self-heating effect rather than band-to-band tunneling. To further exclude undesired oxide trap effects originating from SiO₂ on NDR, hexagonal boron nitride is employed as the supporting dielectric substrate with different channel lengths, achieving a PVCR of ≈2.3 with a maximum peak current of ≈58.4 μA μm⁻¹ at room temperature. These findings promote the development of NDR-based multi-valued logic devices for next generation data processing and storage.