Controlled defect production in monolayer MoS2 via electron irradiation at ultralow accelerating voltages

Abstract

Control on spatial location and density of defects in 2D materials can be achieved using electron beam irradiation. Conversely, ultralow accelerating voltages (less than or equal to 5kV) are used to measure surface morphology, with no expected defect creation. We find clear signatures of defect creation in monolayer (ML) MoS2 at these voltages. Evolution of E' and A1' Raman modes with electron dose, and appearance of defect activated peaks indicate defect formation. To simulate Raman spectra of MoS2 at realistic defect distributions, while retaining density-functional theory accuracy, we combine machine-learning force fields for phonons and eigenmode projection approach for Raman tensors. Simulated spectra agree with experiments, with sulphur vacancies as suggested defects. We decouple defects, doping and carbonaceous contamination using control (hBN covered and encapsulated MoS2) samples. We observe cryogenic PL quenching and defect peaks, and find that carbonaceous contamination does not affect defect creation. These studies have applications in photonics and quantum emitters.

49 pages, 24 figures, 4 tables

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Cited by in corpus (4)

• Creation and Microscopic Origins of Single-Photon Emitters in Transition Metal Dichalcogenides and Hexagonal Boron Nitride
• Quantum light generation with ultra-high spatial resolution in 2D semiconductors via ultra-low energy electron irradiation
• Quantification of 2D Interfaces: Quality of heterostructures, and what is inside a nanobubble
• Quantum siphoning of finely spaced interlayer excitons in reconstructed MoSe2/WSe2 heterostructures