High‐Resolution Microlens‐Assisted Tunable n‐Type Optical Doping in Monolayer MoS ₂

ABSTRACT Atomically thin two‐dimensional transition metal dichalcogenides (2D TMDCs), especially monolayer MoS ₂ , have garnered considerable attention as promising materials for next‐generation transistors. However, their large surface‐to‐volume ratio renders them highly sensitive to defects, underscoring the need for selective, localized, and precise control of their defect profiles. Here, we introduce a laser‐assisted microlens array processing (LAMP) technique that enables highly localized n‐type optical doping of monolayer MoS ₂ by utilizing self‐assembled polystyrene microspheres as microlenses to focus a 532 nm continuous‐wave laser below the diffraction limit. Under low laser powers (40–60 mW), sulfur vacancies are selectively generated without inducing global thermal damage, allowing systematic control of the vacancy concentration. Spectroscopic analyses reveal electron‐donor‐like defects and tunable vacancy density. MoS ₂ transistors treated by LAMP exhibit finely tunable doping, yielding up to a 51‐fold increase in field‐effect mobility and a 37‐fold increase in carrier density, with the enhanced n‐type characteristics remaining stable for several weeks. Unlike direct laser irradiation, LAMP offers high spatial resolution, low energy consumption, and reproducible vacancy engineering while minimizing thermal damage. This complementary metal–oxide–semiconductor‐compatible strategy provides a robust post‐fabrication approach for precise electronic property tuning in two‐dimensional transition metal dichalcogenide devices.