Engineering the Luminescence and Generation of Individual Defect Emitters in Atomically Thin MoS₂

Abstract

We demonstrate the on-demand creation and positioning of photon emitters in atomically thin MoS2 with very narrow ensemble broadening and negligible background luminescence. Focused helium-ion beam irradiation creates 100s to 1000s of such mono-typical emitters at specific positions in the MoS2 monolayers. Individually measured photon emitters show antibunching behavior with a g 2(0) ∼ 0.23 and 0.27. From a statistical analysis, we extract the creation yield of the He-ion induced photon emitters in MoS2 as a function of the exposed area, as well as the total yield of single emitters as a function of the number of He ions when single spots are irradiated by He ions. We reach probabilities as high as 18% for the generation of individual and spectrally clean photon emitters per irradiated single site. Our results firmly establish 2D materials as a platform for photon emitters with unprecedented control of position as well as photophysical properties owing to the all-interfacial nature.

Position-controlled quantum emitters with reproducible emission wavelength in hexagonal boron nitride

“…All of them gave rise to small ensembles of similar emission wavelength. The ensemble distribution, inferred from the PL spectra of all 26 spots, has a full width at half maximum (FWHM) of 3 meV (see Supplementary note 3 ), which is an order of magnitude narrower than the state of the art in 2D materials 23 . We estimate the number of emitters per site to be of order of a few tens, as confirmed by photon correlation measurements (see Supplementary note 4 ).…”

“…Moreover, the latter method results in limited possibilities of subsequent integration. In the 2D material MoS 2 , deterministic positioning with high precision ( ~ 10 nm) has been achieved 22 , 23 using He ion beam, but at the current stage the generated SPEs suffer from low count rates and large linewidths, which constitutes a major drawback for applications to photonic quantum information.…”

The role of chalcogen vacancies for atomic defect emission in MoS2

“…The small exciton redshift in the He-ion treated sample can likely be attributed to the increased dielectric screening in the fully encapsulated samples 28 . Additionally, inhomogeneous broadening effects due to a locally varying dielectric environment near the defects may result in an uncertainty of the defect emission line on the order of several meV 29,30 . The improved inhomogeneous broadening agrees with previous studies of fully hBN encapsulated heterostructures 26 .…”

“…To independently corroborate the value of the thermal activation energy and to quantify the absolute number of defects generated at a given temperature, we conducted a Raman study of additional, thermally annealed samples (Supplementary Note 4). At large enough defect densities, the inter-defect distance, or equivalently the absolute value of the defect density, can be inferred from a shift of the characteristic Raman modes due to phonon confinement effects 30,37,38 . From these experiments we extract an activation energy of (0.48 ± 0.23) eV for thermal defect generation, which agrees well with our in-situ study within the experimental uncertainty.…”

“…These experiments are conducted on graphene/SiC heterostructures. The graphene substrate is essential as conductive support, but it quenches the defect emission, which is slow (100 ns-1 μs) 3,29,30 , and therefore the fast exciton emission (~10 ps) dominates on graphene (Supplementary Note 5) 16,39 . For STM, all samples were prepared in-vacuo by a mild annealing step in vacuum (T annealing < 500 K) to remove adsorbates.…”