Monolayer molybdenum disulfide is considered an extremely promising two-dimensional material for innovative electronics due to its direct bandgap and high charge-carrier mobility. The optical and electronic properties of monolayer MoS₂ can, however, be strongly influenced by the specific synthesis route, posing challenges for industrial-scale production. In this study, we investigated the effects of moderate temperature thermal treatments under a controlled O₂ atmosphere on the properties of monolayer MoS₂ flakes. We found that the treatments can effectively tune the doping level of monolayer MoS₂. Notably, 225 °C was identified as the optimal temperature for enhancing its optical emission properties. Our findings suggest that the removal of sulfur vacancies and impurities underlies these effects, demonstrating a promising approach for tuning the properties of monolayer MoS₂ at mild temperatures.

Monolayer molybdenum disulfide is a semiconducting 2D material presenting very appealing characteristics for its incorporation into electronic flexible devices. At present, atomic vacancies in its structure are known to significantly affect its properties. Nonetheless, the effects of electron irradiation on it are still under investigation. In this work, the structural, electronic, and optical properties of monolayer molybdenum disulfide are studied before and after electron irradiation. By analyzing samples either obtained via a mechanical exfoliation process or grown via chemical vapor deposition, we show that following irradiation no significant change is present. This result indicates a strong resistance to the effect of electron irradiation at energies able to induce the formation of sulfur vacancies. By comparing our results to the current literature, we hypothesize that previously reported effects of electron irradiation are either due to the formation of molybdenum vacancies or to ionization of the electronic shell of this material. The presented results help to shed light on the role of atomic vacancies on the properties of this 2D material from a fundamental point of view and on its usage in extreme environment applications.