Site-selectively generated photon emitters in monolayer MoS2 via local helium ion irradiation

Abstract

Quantum light sources in solid-state systems are of major interest as a basic ingredient for integrated quantum photonic technologies. The ability to tailor quantum emitters via site-selective defect engineering is essential for realizing scalable architectures. However, a major difficulty is that defects need to be controllably positioned within the material. Here, we overcome this challenge by controllably irradiating monolayer MoS 2 using a sub-nm focused helium ion beam to deterministically create defects. Subsequent encapsulation of the ion exposed MoS 2 flake with high-quality hBN reveals spectrally narrow emission lines that produce photons in the visible spectral range. Based on ab-initio calculations we interpret these emission lines as stemming from the recombination of highly localized electron–hole complexes at defect states generated by the local helium ion exposure. Our approach to deterministically write optically active defect states in a single transition metal dichalcogenide layer provides a platform for realizing exotic many-body systems, including coupled single-photon sources and interacting exciton lattices that may allow the exploration of Hubbard physics.

Towards the evaluation of defects in MoS2 using cryogenic photoluminescence spectroscopy

“…Classifying the nature of defects using chemical means is rather inconsistent. However, Mo vacancies should result in the creation of quantum emitters 31 and S vacancies should contribute to the creation of bound defect states. As no signature of quantum emitters was observed one can exclude the Mo vacancies.…”

“…30 A vacancy at the site of a transition metal (Mo or W) also results in the creation of a quantum emitter that can emit photons with a very well-defined energy band. 31 Dramatic changes in the PL spectra with temperature thus allow temperature-dependent and spatially resolved Raman and PL spectroscopy techniques to be great tools to explore the types and location of defects in TMDs.…”

In-situ visualization of hydrogen evolution sites on helium ion treated molybdenum dichalcogenides under reaction conditions

“…An alternative explanation of the basal activity is the generation of defects with a larger formation energy, such as Mo-vacancies and defect complexes, in the basal plane, as a recent photoluminescence study suggests for monolayer MoS 2 . 55 The Mo-vacancies are less mobile than S-vacancies, such that they can additionally contribute to the HER. We point that we do not observe a shift in the sulfur 2p core region at 162 eV after the defect engineering (cf.…”

Wigner crystals in two-dimensional transition-metal dichalcogenides: Spin physics and readout

“…To date, atomic and charge defects in TMDs still prevent the realization of systems with sufficiently low disorder [32]. However, both sample quality and deterministic control over defects [33] have been improving rapidly in recent years and defect densities around n cr can already be achieved. Moreover, WCs require sufficiently low temperature.…”