First-principles simulation of local response in transition metal dichalcogenides under electron irradiation

Electron beam irradiation by transmission electron microscopy (TEM) is a common and effective method for post-synthesis defect engineering in two-dimensional transition metal dichalcogenides (TMDs). Combining density functional theory (DFT) with relativistic scattering theory, we simulate the genera...

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Bibliographic Details
Published in:Nanoscale 2018-02, Vol.10 (5), p.2388-2397
Main Authors: Yoshimura, Anthony, Lamparski, Michael, Kharche, Neerav, Meunier, Vincent
Format: Article
Language:English
Subjects:
Activation energy
Chalcogenides
Crystal defects
Density functional theory
Electron beams
Electron irradiation
Electrons
First principles
Migration
Molybdenum disulfide
Relativism
Relativistic effects
Relativistic theory
Selenides
Sputtering
Temperature dependence
Transmission electron microscopy
Tungsten disulfide
Vacancies
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Summary:Electron beam irradiation by transmission electron microscopy (TEM) is a common and effective method for post-synthesis defect engineering in two-dimensional transition metal dichalcogenides (TMDs). Combining density functional theory (DFT) with relativistic scattering theory, we simulate the generation of such defects in monolayer group-VI TMDs, MoS , WS , MoSe , and WSe , focusing on two fundamental TEM-induced atomic displacement processes: chalcogen sputtering and chalcogen vacancy migration. Our calculations show that the activation energies of chalcogen sputtering depend primarily on the chalcogen species, and are smaller in selenides than in sulfides. Meanwhile, chalcogen vacancy migration activation energies hinge on the transition metal species, being smaller in TMDs containing Mo. Incorporating these energies into a relativistic, temperature-dependent cross section, we predict that, with appropriate TEM energies and temperatures, one can induce migrations in all four group-VI TMDs without simultaneously producing vacancies at a significant rate. This can allow for the formation of complicated defects and extended patterns, and thus, for the controlled manipulation of TMD crystals for targeted functionality, without the risk of substantial collateral damage.
ISSN:2040-3364
2040-3372
DOI:10.1039/c7nr07024a