Atomic structure of intrinsic and electron-irradiation-induced defects in MoTe2

Abstract

Studying the atomic structure of intrinsic defects in two-dimensional transition metal dichalcogenides is difficult since they damage quickly under the intense electron irradiation in transmission electron microscopy (TEM). However, this can also lead to insights into the creation of defects and their atom-scale dynamics. We first show that MoTe 2 monolayers without protection indeed quickly degrade during scanning TEM (STEM) imaging, and discuss the observed atomic-level dynamics, including a transformation from the 1H phase into 1T', three-fold rotationally symmetric defects, and the migration of line defects between two 1H grains with a 60° misorientation. We then analyze the atomic structure of MoTe2 encapsulated between two graphene sheets to mitigate damage, finding the as-prepared material to contain an unexpectedly large concentration of defects. These include similar point defects (or quantum dots, QDs) as those created in the non-encapsulated material, and two different types of line defects (or quantum wires, QWs) that can be transformed from one to the other under electron irradiation. Our density functional theory simulations indicate that the QDs and QWs embedded in MoTe2 introduce new midgap states into the semiconducting material, and may thus be used to control its electronic and optical properties. Finally, the edge of the encapsulated material appears amorphous, possibly due to the pressure caused by the encapsulation.

arXiv comment33 pages, including 7 figures in manuscript and 9 figures in the supplementary information

References in corpus (16)

• A Higher-Accuracy van der Waals Density Functional
• Grains and grain boundaries in highly crystalline monolayer molybdenum disulfide
• A real-space grid implementation of the Projector Augmented Wave method
• Experimental observation of topological Fermi arcs in type-II Weyl semimetal MoTe2
• Prediction of the Weyl semimetal in the orthorhombic MoTe2
• Van der Waals density functional: an appropriate exchange functional
• Structural Semiconductor-to-Semimetal Phase Transition in Two-Dimensional Materials Induced by Electrostatic Gating
• Control of Radiation Damage in MoS2 by Graphene Encapsulation
• Van der Waals pressure and its effect on trapped interlayer molecules
• Manipulating low-dimensional materials down to the level of single atoms with electron irradiation
• The pristine atomic structure of MoS2 monolayer protected from electron radiation damage by graphene
• Raman signatures of inversion symmetry breaking and structural phase transition in type-II Weyl semimetal MoTe2
• Defect-induced conductivity anisotropy in MoS2 monolayers
• Line Defects in Molybdenum Disulfide Layers
• Phonon Anharmonicity in Bulk $T_d$-MoTe${}_2$
• The dynamics of copper intercalated molybdenum ditelluride

Cited by in corpus (6)

• Deep Learning Enabled Strain Mapping of Single-Atom Defects in 2D Transition Metal Dichalcogenides with Sub-picometer Precision
• Tunable spin-polarized edge currents in proximitized transition metal dichalcogenides
• Magnon valley Hall effect in CrI3-based vdW heterostructures
• In situ Imaging of an Anisotropic Layer-by-Layer Phase Transition in Few-Layer MoTe2
• Novel 2D vanadium sulphides: synthesis, atomic structure engineering and charge density waves
• Atomic-scale Oxygen-mediated Etching of 2D MoS${}_2$ and MoTe${}_2$