Fig. 1

Deterministically induced defect emitters in atomically thin MoS₂ realized by focused helium ions. a Schematic illustration of the exposed MoS₂/hBN van der Waals heterostructure. b Helium ion microscopy image taken at a dose of σ = 2.2 ⋅ 10¹² cm⁻². The scale bar is 10 μm. c Spatially resolved and spectrally integrated photoluminescence mapping. The colored pixels depict the occurrence of emitters within 500 μeV wide energy bins (highlighted by colored arrows in d). d Bottom panel: typical low-temperature (10 K) μ-PL spectra of the exposed (black) and unexposed (red) hBN/MoS₂/hBN heterostructure. The spectra of exposed MoS₂ feature emission from mobile excitons \(\,^0X_{1s}^A\) and trions \(\,^ - X_{1s}^A\), as well as single emission lines X_L (open triangle) at lower energies. Top panel: a histogram of the emission energies detuned by ΔE_L = E(\(\,^0X_{1s}^A\)) − E(X_L) below \(\,^0X_{1s}^A\). e Power dependence: \(\,^0X_{1s}^A\) shows an expected linear power dependence, while the X_L emission saturates for higher excitation powers (data for the emitter highlighted by open triangle in d). f–i DFT calculated spin-up (black) and spin-down (red) density of states (DOS) of the neutral \({\mathrm{V}}_{Mo}^0\), single negatively \({\mathrm{V}}_{Mo}^{1 - }\), double negatively \({\mathrm{V}}_{Mo}^{2 - }\), and triple negatively charged \({\mathrm{V}}_{Mo}^{3 - }\) molybdenum vacancy. The DOS of \({\mathrm{V}}_{Mo}^0\) shows doublet e-p, e-pd and singlet a₁-pd defect states inside the band gap. The a₁-p singlet state is situated within the valence band. The more electrons are added to the vacancy the closer the defect states and the DFT computed Fermi level energy \(E_F^{DFT}\) shift to the conduction band minimum (CBM) because of the on-site Coulomb repulsion