Voltage-Induced Oxidation for Enhanced Purity and Reproducibility of Quantum Emission in Monolayer 2D Materials
We report a voltage-induced oxidation technique using conductive atomic force microscopy to enhance the single-photon purity and reproducibility of quantum emitters in monolayer tung-sten diselenide (WSe2). By applying a controlled electric field across a monolayer WSe2/poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) on a silicon substrate, localized oxidation is induced around nanoindented emitter sites in the WSe2. This treatment selectively suppresses defect-bound exciton emissions while preserving emission from pristine regions within the indentations. Photoluminescence and second-order correlation measurements at 18 K demonstrate a substantial increase in single-photon purity when comparing emitters from untreated and voltage-treated regions. Emitters from untreated regions showed average values of g2(0) near or above the 0.5 threshold. In contrast, emitters from voltage-treated regions exhibited g2(0) values consistently below 0.14, with most falling near 0.05, demonstrating high-purity single-photon emission well below the g2(0) < 0.5 threshold. This enhancement results from the oxidation-induced suppression of spurious luminescence from the area around the quantum emitter site that is spectrally degenerate with the single-photon wavelength. This approach offers nonvolatile, spatially selective control over the emitter environment without degrading the emission intensity, improving both purity and stability. It provides a scalable route for integrating high-quality quantum emitters in two-dimensional materials into photonic platforms. Integration with spectral tuning strategies such as strain engineering, local dielectric patterning, or electrostatic gating could further enable deterministic, wavelength-selective single-photon sources for advanced quantum photonic applications