Gate-tunable negative differential resistance in multifunctional van der Waals heterostructure

TL;DR

This paper demonstrates a gate-tunable negative differential resistance in a 2D heterostructure device, enabling multifunctional electronic behavior suitable for neuromorphic and energy-efficient applications.

Contribution

It introduces a novel dual-gated heterojunction device with highly tunable NDR behavior based on Type III band alignment in 2D semiconductors.

Findings

Achieved gate-tunable NDR with a peak-to-valley ratio of ~3 at 150K.

Demonstrated multifunctional rectifying behavior in a 2D heterostructure.

Identified interband tunneling as the mechanism behind NDR.

Abstract

Two-dimensional (2D) semiconductors have emerged as leading candidates for the development of low-power and multifunctional computing applications, thanks to their qualities such as layer-dependent band gap tunability, high carrier mobility, and excellent electrostatic control. Here, we explore a pair of 2D semiconductors with broken-gap (Type III) band alignment and demonstrate a highly gate-tunable p-MoTe$_{2}$/n-SnS$_{2}$ heterojunction tunnel field-effect transistor with multifunctional behavior. Employing a dual-gated asymmetric device geometry, we unveil its functionality as both a forward and backward rectifying device. Consequently, we observe a highly gate-tunable negative differential resistance (NDR), with a gate-coupling efficiency of $\eta \simeq 0.5$ and a peak-to-valley ratio of $\sim$ 3 down to 150K. By employing density functional theory and exploring the density of states, we determine that interband tunneling within the valence bands is the cause of the observed NDR characteristics. The combination of band-to-band tunneling and gate controllability of NDR signal open the pathway for realizing gate-tunable 2D material-based neuromorphic and energy-efficient electronics.