From point to extended defects in two-dimensional MoS<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>2</mml:mn></mml:msub></mml:math>: Evolution of atomic structure under electron irradiation

Komsa, Hannu‐Pekka; Kurasch, Simon; Lehtinen, Ossi; Kaiser, Ute; Krasheninnikov, Arkady V.

doi:10.1103/physrevb.88.035301

Cited by 449 publications

(371 citation statements)

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“…3f) that results in a migration barrier of about 1.4 eV. This energy barrier is considerably lower than the diffusion energy barrier for a single S vacancy (V S ), which is estimated to be 2.3 eV for MoS 2 of the same lattice 28 , highlighting the important role of the dislocations and their interaction with S vacancies in mediating both the dislocation and S migration in TMDs through the coupled displacement of W atoms. Without the S vacancy in the dislocation core (Fig.…”

Section: Resultsmentioning

confidence: 95%

Dislocation motion and grain boundary migration in two-dimensional tungsten disulphide

et al. 2014

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Dislocations have a significant effect on mechanical, electronic, magnetic and optical properties of crystals. For a dislocation to migrate in bulk crystals, collective and simultaneous movement of several atoms is needed. In two-dimensional crystals, in contrast, dislocations occur on the surface and can exhibit unique migration dynamics. Dislocation migration has recently been studied in graphene, but no studies have been reported on dislocation dynamics for two-dimensional transition metal dichalcogenides with unique metal-ligand bonding and a three-atom thickness. This study presents dislocation motion, glide and climb, leading to grain boundary migration in a tungsten disulphide monolayer. Direct atomic-scale imaging coupled with atomistic simulations reveals a strikingly low-energy barrier for glide, leading to significant grain boundary reconstruction in tungsten disulphide. The observed dynamics are unique and different from those reported for graphene. Through strain field mapping, we also demonstrate how dislocations introduce considerable strain along the grain boundaries and at the dislocation cores.

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Section: Resultsmentioning

confidence: 95%

Dislocation motion and grain boundary migration in two-dimensional tungsten disulphide

et al. 2014

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“…On the other hand, the low-energy response of MoS 2 flakes might be advantageous for photocatalysis [20]. Similar optical properties might also be exhibited by the metallic states on defect lines [63] and domain boundaries [64][65][66]. All in all, our study emphasizes the rich optical response of MoS 2 nanoflakes, simultaneously illustrating the importance of powerful analysis tools for extracting information on the optical response.…”

Section: Discussionmentioning

confidence: 95%

Effect of edge plasmons on the optical properties of MoS2 monolayer flakes

et al. 2017

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Finite MoS 2 nanoparticles are known to support metallic edge states that are responsible for their catalytic activity. In this work we employ time-dependent density-functional theory (TDDFT) to study the influence of such edge states on the optical properties of triangular MoS 2 monolayer flakes. We find that the edge states support collective plasmon-like excitations that couple strongly to the optical field leading to pronounced absorption peaks below the onset of interband transitions on the basal plane. Additionally, structural relaxation of the flakes can significantly distort the edge states. Thus, we observe that while an evenly-spaced edge configuration supports one-dimensional (1D) plasmon modes similar to those of an ideal 1D electron gas, the relaxed structures show mixed plasmon and single-electron excitations in the low-energy response. Our findings illustrate the sensitivity of the optical response of MoS 2 nanostructures to the details of the edge configuration.

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“…The energies should be compared to those of isolated vacancies or the most favorable types of vacancy clusters. While staggered vacancy lines were found to be the preferred vacancy cluster in MoS 2 , [38,46] the situation seems to be different in tungsten chalcogenides where isolated double vacancies are lower in energy. Moreover, in MoS 2 the staggered vacancy line configuration has lower energy than any of the inversion domains.…”

Section: Wwwadvelectronicmatdementioning

confidence: 93%

“…Upon increase of the vacancy concentration, they agglomerate to form vacancy line structures. [31,38,46] The agglomeration is enabled by the diffusion of the vacancies, which is further driven by kinetic energy obtained from collisions with the energetic electrons. [46] When concentration of vacancies increases the atomic network becomes unstable with regard to the formation of line defects.…”

Section: Progress Reportmentioning

confidence: 99%

“…[31,38,46] The agglomeration is enabled by the diffusion of the vacancies, which is further driven by kinetic energy obtained from collisions with the energetic electrons. [46] When concentration of vacancies increases the atomic network becomes unstable with regard to the formation of line defects. An example of the double-vacancy line structure in the staggered configuration, which is the lowest energy configuration in many TMDs, is shown in Figure 2b, and the corresponding atomic structure is illustrated in Figure 2c.…”

Section: Progress Reportmentioning

confidence: 99%

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Engineering the Electronic Properties of Two‐Dimensional Transition Metal Dichalcogenides by Introducing Mirror Twin Boundaries

Komsa

Krasheninnikov

2017

Adv Elect Materials

Self Cite

100

109

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Grain boundaries in 2D materials can have marked influence on the material properties. The effects can be not only detrimental, but also beneficial in transition metal dichalcogenides (TMDs), so that controlling the density and type of the boundaries in these systems should be important for engineering their properties. However, this is often possibly only during the growth stage. Molybdenum and tungsten dichalcogenides feature a particular set of 60° mirror twin boundaries, which are reported to occur upon merging of the growing flakes, to appear during growth to accommodate for the nonstoichiometry of the sample, or to be produced a posteriori by electron irradiation or thermal annealing. Furthermore, different preparation conditions lead to different atomic structure of the boundary, which consequently exhibit different electronic properties. This has obviously garnered interest for the ability to control grain boundary types and densities. In this progress report, the recent experimental and theoretical work related to the characterization of mirror twin boundaries is reviewed. A consistent set of formation energies for the mirror twin boundaries is provided, which then allows a coherent picture on the formation mechanisms under different conditions to be drawn. Finally, the electronic structure of these boundaries is analyzed and their potential applications are discussed.

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From point to extended defects in two-dimensional MoS2: Evolution of atomic structure under electron irradiation

Cited by 449 publications

References 62 publications

Dislocation motion and grain boundary migration in two-dimensional tungsten disulphide

Dislocation motion and grain boundary migration in two-dimensional tungsten disulphide

Effect of edge plasmons on the optical properties of MoS2 monolayer flakes

Engineering the Electronic Properties of Two‐Dimensional Transition Metal Dichalcogenides by Introducing Mirror Twin Boundaries

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