Torsional strain engineering of transition metal dichalcogenide nanotubes: An ab initio study

TL;DR

This study uses ab initio calculations to explore how twisting transition metal dichalcogenide nanotubes alters their electronic properties, revealing potential for tunable device applications.

Contribution

It provides a detailed analysis of torsional effects on TMD nanotubes' electronic structure, highlighting the transition from semiconducting to metallic behavior due to orbital rehybridization.

Findings

Semiconducting nanotubes experience bandgap reduction with twist.

Metallic nanotubes remain metallic after deformation.

Torsion induces semiconductor to metal transitions.

Abstract

We study the effect of torsional deformations on the electronic properties of single-walled transition metal dichalcogenide (TMD) nanotubes. In particular, considering forty-five select armchair and zigzag TMD nanotubes, we perform symmetry-adapted Kohn-Sham density functional theory calculations to determine the variation in bandgap and effective mass of charge carriers with twist. We find that metallic nanotubes remain so even after deformation, whereas semiconducting nanotubes experience a decrease in bandgap with twist -- originally direct bandgaps become indirect -- resulting in semiconductor to metal transitions. In addition, the effective mass of holes and electrons continuously decrease and increase with twist, respectively, resulting in n-type to p-type semiconductor transitions. We find that this behavior is likely due to rehybridization of orbitals in the metal and chalcogen atoms, rather than charge transfer between them. Overall, torsional deformations represent a powerful avenue to engineer the electronic properties of semiconducting TMD nanotubes, with applications to devices like sensors and semiconductor switches.