Low‐Power Negative‐Differential‐Resistance Device for Sensing the Selective Protein via Supporter Molecule Engineering

Van der Waals (vdW) heterostructures composed of atomically thin two‐dimensional (2D) materials have more potential than conventional metal‐oxide semiconductors because of their tunable bandgaps, and sensitivities. The remarkable features of these amazing vdW heterostructures are leading to multi‐functional logic devices, atomically thin photodetectors, and negative differential resistance (NDR) Esaki diodes. Here, an atomically thin vdW stacking composed of p‐type black arsenic (b‐As) and n‐type tin disulfide (n‐SnS(2)) to build a type‐III (broken gap) heterojunction is introduced, leading to a negative differential resistance device. Charge transport through the NDR device is investigated under electrostatic gating to achieve a high peak‐to‐valley current ratio (PVCR), which improved from 2.8 to 4.6 when the temperature is lowered from 300 to 100 K. At various applied‐biasing voltages, all conceivable tunneling mechanisms that regulate charge transport are elucidated. Furthermore, the real‐time response of the NDR device is investigated at various streptavidin concentrations down to 1 pm, operating at a low biasing voltage. Such applications of NDR devices may lead to the development of cutting‐edge electrical devices operating at low power that may be employed as biosensors to detect a variety of target DNA (e.g., ct‐DNA) and protein (e.g., the spike protein associated with COVID‐19).