Bilayer

Sediment

Chemical physics

Stacking

Biology

Metallurgy

Materials science

Deposition (geology)

Biochemistry

Molecule

Pulsed laser deposition

Grain boundary

Paleontology

Laser

Physics

Nanotechnology

Organic chemistry

Membrane

Crystallite

Optics

van der Waals force

Microstructure

Pulsed laser

Thin film

Condensed matter physics

Monolayer

Heterojunction

Crystallography

Chemistry

Crystallographic defect

Optoelectronics

ACS Nano

Pulsed laser deposition (PLD) can be considered a powerful method for the growth of two-dimensional (2D) transition-metal dichalcogenides (TMDs) into van der Waals heterostructures. However, despite significant progress, the defects in 2D TMDs grown by PLD remain largely unknown and yet to be explored. Here, we combine atomic resolution images and first-principles calculations to reveal the atomic structure of defects, grains, and grain boundaries in mono- and bilayer MoS2 grown by PLD. We find that sulfur vacancies and MoS antisites are the predominant point defects in 2D MoS2. We predict that the aforementioned point defects are thermodynamically favorable under a Mo-rich/S-poor environment. The MoS2 monolayers are polycrystalline and feature nanometer size grains connected by a high density of grain boundaries. In particular, the coalescence of nanometer grains results in the formation of 180° mirror twin boundaries consisting of distinct 4- and 8-membered rings. We show that PLD synthesis of bilayer MoS2 results in various structural symmetries, including AA′ and AB, but also turbostratic with characteristic moiré patterns. Moreover, we report on the experimental demonstration of an electron beam-driven transition between the AB and AA′ stacking orientations in bilayer MoS2. These results provide a detailed insight into the atomic structure of monolayer MoS2 and the role of the grain boundaries on the growth of bilayer MoS2, which has importance for future applications in optoelectronics.

Intrinsic Defects in MoS<sub>2</sub> Grown by Pulsed Laser Deposition: From Monolayers to Bilayers

Intrinsic Defects in MoS2 Grown by Pulsed Laser Deposition: From Monolayers to Bilayers

Intrinsic Defects in MoS₂ Grown by Pulsed Laser Deposition: From Monolayers to Bilayers