Localized Excitons in Monolayer WSe₂ on Nano-Roughness Glass Substrates

Two-dimensional (2D) transition metal dichalcogenides (TMDs) materials are attractive systems with strong spin-valley coupling and excitonic effects. Nano-strain and defects engineering in TMDs play an important role in controlling their optical properties, particularly for generating atomic defect-based single-photon emitters, which are the platform to develop on-chip integrated single-photon sources for quantum information technology¹.<br/>Here, we have investigated optical and magneto-optical properties of a monolayer WSe₂ on Tb³⁺- borogermanate glasses with different Tb³⁺ concentrations. Our results show that by using a simple method of a lithography-free approach, it is possible to generate nano-roughness glasses to localize excitons by local strain in a monolayer WSe₂. Remarkably, the photoluminescence (PL) reveal several stable sharp doublet emissions with small line jittering effects and with typical fine-structure splittings of ≈ 760 μeV from the same quantum dot (QD)-like emitters which are associated with an anisotropic electron–hole exchange interaction. In addition, the correlation function was measured for some emission lines and displayed a clearly effect of photon antibunching. In order to investigate in more detail the nature of these emission peaks, we have also measured circularly polarization-resolved PL under magnetic field (Faraday and Voigt configurations). Under perpendicular magnetic field, the extracted g-factor values for these PL peaks are ∼8.4–9.8. Under parallel magnetic field, a clear red-shift for several emission peaks was observed for both circularly polarized PL detections. In general, our results suggest that nano-rough engineering on glass substrates is a promising tool for exploring single emitters for possible integration with photonics systems in quantum information technology¹.<br/><br/><b>References:</b><br/>1-Caique Serati de Brito et al, Applied Physics Letters 121, 070601 (2022).