The role of chalcogen vacancies for atomic defect emission in MoS2

Abstract

For two-dimensional (2D) layered semiconductors, control over atomic defects and understanding of their electronic and optical functionality represent major challenges towards developing a mature semiconductor technology using such materials. Here, we correlate generation, optical spectroscopy, atomic resolution imaging, and ab initio theory of chalcogen vacancies in monolayer MoS2. Chalcogen vacancies are selectively generated by in-vacuo annealing, but also focused ion beam exposure. The defect generation rate, atomic imaging and the optical signatures support this claim. We discriminate the narrow linewidth photoluminescence signatures of vacancies, resulting predominantly from localized defect orbitals, from broad luminescence features in the same spectral range, resulting from adsorbates. Vacancies can be patterned with a precision below 10 nm by ion beams, show single photon emission, and open the possibility for advanced defect engineering of 2D semiconductors at the ultimate scale.

Growth of highly conducting MoS2-xNx thin films with enhanced 1T' phase by pulsed laser deposition and exploration of their nanogenerator application

“…The low-temperature resistivity data can be best fitted with the Mott-variable range hopping (Mott-VRH) model (i.e. ln σ∝ 1/T 1/( d +1) ) where σ is the conductivity and d the dimension, signifying the important role of Anderson localization due to intrinsic disorder effect (possible structural defects, vacancies, and dislocations to lower the strain energy) for this insulating-like behavior ( Figure S10 ) ( Cho et al., 2021 ), ( Zhou et al., 2016 ) In addition, much lower activation energy of MoS 2-x N x (∼30.6 meV) is observed over that of pristine MoS 2 (∼91.3 meV) ( Figure S11 ) which also indicates the modification in the electronic correlation and consequent enhancement in electrical conductivity ( Mitterreiter et al., 2021 ). Moreover, reported theoretical calculations reveal that the structural distortion-induced changes in crystal field splitting opens up a gap of ∼100 meV for the semiconducting 1Tʹ phase ( Pal et al., 2017 ).…”

Deterministic and Scalable Generation of Exciton Emitters in 2D Semiconductor Nanodisks

“…The dangling bonds generated during external treatments like focused ion beam or plasma etching may also induce broadening for emitter peaks. [56,57] To reveal the size effect to confine the excitons and promote the isolated emitter-like PL features, we performed PL measurements on nanodisks with various diameters. As shown in the fluorescence image and PL map (Figure 2a), both flake and disk samples show the bright PL at RT and 4.2 K, without signs of quenching or degradation after fabrication.…”

Nanomaterials for Quantum Information Science and Engineering

“…Like hBN, arrays of defect-based QEs can be deterministically created in TMDs using a Helium ion FIB [450,452,463] or e-beam irradiation [460] . The optically active defects have been shown to be chalcogen vacancies [451] . Barthelmi et al used a He-ion beam to create sulfur vacancies in hBN-encapsulated MoS2 (Fig.…”