Negative Differential Resistance Effect in “Cold” Metal Heterostructure Diodes

Negative differential resistance (NDR) devices are significant for logic, memory and radiofrequency applications. Herein, we study the electronic and quantum transport properties of “cold” metals 2H MX₂ (M = Nb, Ta; X = S, Se) and their heterojunction (HJ) NDR diodes. Owing to the energy gaps of such 2H MX₂ close to the Fermi level, the broken-gap structure can be formed by the MSe₂/MS₂ HJs. A favorable peak current thus is achieved benefitting from the large conductivity of metallic 2H MSe₂/MS₂ HJs. The promising peak-valley ratio PVR (51) and peak current ( $5.1\times 10^{4} \mu \text{A}/\mu \text{m}$ ) is obtained by edge contact NbSe₂/NbS₂ HJ NDR device. The study of “cold” metal NDR performance provides a practical solution for NDR devices to achieve desired PVR and peak currents simultaneously.