Oxidation-induced modulation of photoresponsivity in monolayer MoS 2 with sulfur vacancies.

Two-dimensional transition metal dichalcogenides (TMDs), such as MoS ₂ , hold great promise for next-generation electronics and optoelectronics due to their unique properties. However, the ultrathin nature of these materials renders them vulnerable to structural defects and environmental factors, which significantly impact their performance. Sulfur vacancies (V _S ) are the most common intrinsic defects in MoS ₂ , and their impact on device performance in oxidising environments remains understudied. This study investigates the impact of V _S defects on the photoresponsivity of CVD-grown monolayer MoS ₂ devices, when exposed to oxidising environments at high temperatures. Our findings reveal a dynamic process of defect generation and healing through oxygen passivation, leading to a significant difference in photocurrent between environments. Temperature-dependent analysis shows defect healing and a notable reduction in defect density upon cooling. This study provides crucial insights into the stability and performance of 2D materials-based devices under varying environmental conditions, essential for designing and controlling the performance of TMD-based devices. Our results pave the way for the development of robust and reliable 2D materials-based electronics and optoelectronics.