Healing Atom Vacancy and Oxidation Suppression in Solution-Processed MoS 2 through Sulfur Vapor Annealing

High Resolution Image Download MS PowerPoint Slide Sulfur vacancies and interface oxidation are the major challenging issues causing degradation of the structural and electronic properties of molybdenum disulfide (MoS 2 ). This study demonstrates a sulfur vapor annealing technique to restore sulfur vacancies and suppress oxidation in solution-processed MoS 2 films on Si 3 N 4 surfaces. MoS 2 films deposited with precursor concentrations ranging from 5 to 40 mM were annealed at 700 °C under argon (Ar) and sulfur vapor (S-vapor) atmospheres. High-resolution transmission electron microscopy (HRTEM) reveals enhanced crystallinity and a well-ordered layered structure with an interlayer space of ∼0.65 nm in S-vapor-annealed films, compared to disordered and defect structures in Ar-annealed counterparts. X-ray photoelectron spectroscopy (XPS) confirms a near-stoichiometric S/Mo ratio (∼2:1) and a consistently low Mo 6+ /Mo 4+ ratio (∼0.1–0.15), suggesting minimal oxidation and stable Mo 4+ states in S-vapor-annealed films. Thermal desorption spectroscopy (TDS) analysis displays increased SO ( m / z = 48) and SO 2 desorption ( m / z = 64) in S-vapor-annealed films, especially at higher precursor concentrations, indicating increased sulfur incorporation. The results demonstrate sulfur vapor annealing to be a very effective post-treatment technique to improve the structural integrity and chemical stability of solution-processed MoS 2 films for high-performance electronic devices.