How does quantum confinement influence the electronic structure of transition metal sulfides TmS2

TL;DR

This paper investigates how quantum confinement affects the electronic properties of transition metal sulfides TmS2, revealing size-dependent transitions from metallic to semiconducting behavior in certain compounds.

Contribution

It demonstrates through first principles calculations that quantum confinement can tune the electronic structure of layered TmS2 materials at the nanoscale.

Findings

Monolayer MoS2 becomes a direct bandgap semiconductor.

WS2 exhibits similar electronic properties across sizes.

NbS2 and ReS2 remain metallic regardless of size.

Abstract

Bulk MoS2, a prototypical layered transition-metal dichalcogenide, is an indirect band gap semiconductor. Reducing its size to a monolayer, MoS2 undergoes a transition to the direct band semiconductor. We support this experimental observation by first principles calculations and show that quantum confinement in layered d-electron dichalcogenides results in tuning the electronic structure at the nanoscale. We further studied the properties of related TmS2 nanolayers (Tm = W, Nb, Re) and show that the isotopological WS2 exhibits similar electronic properties, while NbS2 and ReS2 remain metallic independent on size.