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The influence of atomic vacancy defects at different concentrations on electronic properties of M... more The influence of atomic vacancy defects at different concentrations on electronic properties of MoS_2 and WS_2 monolayers is studied by means of Slater-Koster tight-binding model with non-orthogonal sp^3d^5 orbitals and including the spin-orbit coupling. The presence of vacancy defects induces localized states in the bandgap of pristine MoS_2 and WS_2, which have potential to modify the electronic structure of the systems, depending on the type and concentration of the defects. It is shown that although the contribution of metal (Mo or W) d orbitals is dominant in the formation of midgap states, the sulphur p and d orbitals have also considerable contribution in the localized states, when metal defects are introduced. Our results suggest that Mo and W defects can turn the monolayers into p-type semiconductors, while the sulphur defects make the system a n-type semiconductor, in agreement with ab initio results and experimental observations.
We theoretically explore the effect of metal and disulphur vacancies on electronic and optical pr... more We theoretically explore the effect of metal and disulphur vacancies on electronic and optical properties of MoS2 and WS2 monolayers based on a Slater-Koster tight-binding model and including the spin-orbit coupling. We show that the vacancy defects create electronic flat bands by shifting the Fermi level towards the valence band, indicating that both types of vacancies may act as acceptor sites. The optical spectra of the pristine monolayers show step-like features corresponding to the transition from spin split valence band to the conduction band minimum, whereas the defective monolayers exhibit additional peaks in their spectra arising from induced midgap states in their band structures. We find that Mo and W vacancies contribute mostly in the low-energy optical spectrum, while the S2 vacancies enhance the optical conductivity mainly in the visible range of the spectrum. This suggests that depending on the type of vacancy, the atomic defects in MoS2 and WS2 monolayers may increas...
Journal of Physics and Chemistry of Solids
The influence of atomic vacancy defects at different concentrations on electronic properties of M... more The influence of atomic vacancy defects at different concentrations on electronic properties of MoS_2 and WS_2 monolayers is studied by means of Slater-Koster tight-binding model with non-orthogonal sp^3d^5 orbitals and including the spin-orbit coupling. The presence of vacancy defects induces localized states in the bandgap of pristine MoS_2 and WS_2, which have potential to modify the electronic structure of the systems, depending on the type and concentration of the defects. It is shown that although the contribution of metal (Mo or W) d orbitals is dominant in the formation of midgap states, the sulphur p and d orbitals have also considerable contribution in the localized states, when metal defects are introduced. Our results suggest that Mo and W defects can turn the monolayers into p-type semiconductors, while the sulphur defects make the system a n-type semiconductor, in agreement with ab initio results and experimental observations.
We theoretically explore the effect of metal and disulphur vacancies on electronic and optical pr... more We theoretically explore the effect of metal and disulphur vacancies on electronic and optical properties of MoS2 and WS2 monolayers based on a Slater-Koster tight-binding model and including the spin-orbit coupling. We show that the vacancy defects create electronic flat bands by shifting the Fermi level towards the valence band, indicating that both types of vacancies may act as acceptor sites. The optical spectra of the pristine monolayers show step-like features corresponding to the transition from spin split valence band to the conduction band minimum, whereas the defective monolayers exhibit additional peaks in their spectra arising from induced midgap states in their band structures. We find that Mo and W vacancies contribute mostly in the low-energy optical spectrum, while the S2 vacancies enhance the optical conductivity mainly in the visible range of the spectrum. This suggests that depending on the type of vacancy, the atomic defects in MoS2 and WS2 monolayers may increas...
Journal of Physics and Chemistry of Solids