Electrostatic tuning of transmission in NbS2/WSe2 Lateral Hetero-Structures: A computational study

We present a first-principles computational study of the NbS2/WSe2 junction between two transition metal dichalcogenide monolayers as a prototypical metal/semiconductor 2-dimensional (2D) lateral hetero-structure (LH) to investigate the effects of electrostatic perturbations on electron transport in 2D LH systems. In order to simulate electrostatic (charged or dipolar) defects in the substrate, we introduce ionic systems (LiF lines) properly positioned in two different configurations and study cases, corresponding to modeling two different phenomena: (i) an electrostatic defect in the middle of the semiconducting part of the hetero-structure (qualitatively analogous to a gate voltage opposing transmission), and (ii) an electrostatic perturbation re-aligning and flattening the electrostatic potential along the asymmetric LH junction. In the former case, we determine a substantial decrease of transmission even for small values of the perturbation (providing information that can be used to achieve a quantitative correlation between substrate-induced defectivity and device performance degradation in experiment), whereas in the latter we predict that electron transport can be significantly enhanced by properly tuning external electrostatic perturbations at the interface.