Atomistic defects as single-photon emitters in atomically thin MoS2

Abstract

Precisely positioned and scalable single-photon emitters (SPEs) are highly desirable for applications in quantum technology. This Perspective discusses single-photon-emitting atomistic defects in monolayers of MoS2 that can be generated by focused He-ion irradiation with few nanometers positioning accuracy. We present the optical properties of the emitters and the possibilities to implement them into photonic and optoelectronic devices. We showcase the advantages of the presented emitters with respect to atomistic positioning, scalability, long (microsecond) lifetime, and a homogeneous emission energy within ensembles of the emitters. Moreover, we demonstrate that the emitters are stable in energy on a timescale exceeding several weeks and that temperature cycling narrows the ensembles' emission energy distribution.

The role of chalcogen vacancies for atomic defect emission in MoS2

“…Vacancies introduce a deep center with sharp optical emission, markedly different from previously observed broad luminescence bands [4][5][6][7][8] . Comparing annealed vs. He-ion treated MoS 2 , we establish that the recently discovered single-photon emitters in He-ion irradiated MoS 2 originate from chalcogen vacancies 3 . The latter can be deterministically created with a precision below 10 nm 9 , underscoring the potential of defect engineering for twodimensional (quantum-) optoelectronics.…”

“…ontrol over atomic defects is the foundation of today's semiconductor technology. For two-dimensional van der Waals semiconductors, the term "defect engineering" has been coined to suggest that, by introducing defects, these materials can be engineered beyond the established concepts of doping or alloying 1 , enabling advanced functionality, such as single photon sources 2,3 or photocatalysis with chemical specificity 1 . Nevertheless, the microscopic understanding of defect-related modifications remains elusive due to a lack of thorough correlation between atomic structure and resulting macroscopic electronic and optical properties.…”

“…While these point-like emitters appear randomly in as-prepared samples, they can be generated deterministically via engineered nanoscale strain potentials 2 . Recently, our group has demonstrated that atomic point defects, which are created deterministically by focused He-ion irradiation using a helium ion microscope (HIM) 9 , act as narrow and reproducible singlephoton emitters, yet without a local strain potential 3,27 . Here, we disentangle broad defect emission due to adsorbates, which can be desorbed by in-vacuo annealing at moderate temperatures, and narrow defect emission via sulfur vacancies, which are generated both by annealing at high temperatures and He-ion irradiation.…”

Strategy and Future Prospects to Develop Room-Temperature-Recoverable NO2 Gas Sensor Based on Two-Dimensional Molybdenum Disulfide

“…In addition, these defects are susceptible to ambient environments conditions [ 271 , 272 ]. Defects can also be created through the irradiations, metal doping and functionalization [ 273 , 274 ]. Thus, MoS 2 structures unavoidably have various defects in terms of vacancies, dopants, adsorbates, adatoms, and impurities.…”

Remote Phonon Control of Quantum Dots and Other Artificial Atoms

“…[166] However, atomic defects can also be created on purpose in TMDCs, for example, by He ion irradiation which show single photon emission. [167,168] These rapid recent developments demonstrate that single photon emitters in TMDCs will establish a new class of artificial atoms in the solid state that can be interfaced with different kinds of strain sources. It has been shown that already excitons in plain mono-and bilayer TMDCs react to external strain tuning [169,170] and that even the exciton-phonon coupling can be controlled in this way.…”