Two-dimensional transition metal dichalcogenides under electron irradiation: defect production and doping

TL;DR

This study combines simulations and experiments to understand how two-dimensional transition metal dichalcogenides respond to electron irradiation, revealing defect formation and doping methods to engineer their electronic properties.

Contribution

It provides the first comprehensive analysis of defect production and doping in 2D TMDs under electron irradiation, validated by experimental observations.

Findings

Displacement threshold energies for 21 TMD compounds calculated.

Vacancy formation observed at 80 keV electron beam in MoS2.

Doping of TMDs achieved by filling vacancies with impurity atoms.

Abstract

Using first-principles atomistic simulations, we study the response of atomically-thin layers of transition metal dichalcogenides (TMDs) - a new class of two-dimensional inorganic materials with unique electronic properties - to electron irradiation. We calculate displacement threshold energies for atoms in 21 different compounds and estimate the corresponding electron energies required to produce defects. For a representative structure of MoS2, we carry out high-resolution transmission electron microscopy experiments and validate our theoretical predictions via observations of vacancy formation under exposure to a 80 keV electron beam. We further show that TMDs can be doped by filling the vacancies created by the electron beam with impurity atoms. Thereby, our results not only shed light on the radiation response of a system with reduced dimensionality, but also suggest new ways for engineering the electronic structure of TMDs.