2D-Alloying-Mediated Passivation of Native Point Defects in Atomically-Thin Mo1–xWxS2 Ternary Monolayers

Atomically thin transition metal dichalcogenides inherently exhibit native point defects due to the low formation energy of chalcogen vacancies limiting the performance of nano optoelectronic devices. We thoroughly explore the nature of native defects in metal–organic chemical vapor deposited pristine MoS₂ and Mo_1–xW_xS₂ monolayers utilizing high-resolution transmission electron microscopy. Our findings suggest that W alloying induces a tensile strain of 2.32%, which significantly reduces the sulfur vacancy defect density, thereby dramatically enhancing the photoluminescence yield by 32 times for x ≥ 0.5. This work provides insights into the relationship between native sulfur vacancy defects and strain in Mo_1–xW_xS₂ for improved device performance.