Mechanically reliable and electronically uniform monolayer MoS₂ by passivation and defect healing

Monolayer molybdenum disulfide (MoS₂), a two-dimensional transition metal dichalcogenide (2D TMD), is at the forefront of logic device scaling efforts due to its semiconducting properties, good carrier mobility, and atomically thin structure. However, the high defect density of monolayer MoS₂ hinders its reliability for long-term, device-scale applications. Here, we show that a superacid treatment, previously shown to enhance the photoluminescence efficiency of sulfur-based 2D TMDs by two orders of magnitude, also improves the mechanical reliability and electronic uniformity of monolayer MoS₂. Treated samples exhibit a ~2× increase in static fatigue reliability, a ~10× improvement in cyclic wear reliability, and no premature failure during mechanical testing. X-ray photoelectron spectroscopy confirms reduced defect density, while ab initio molecular dynamics and density functional theory suggest that passivation delays failure propagation and reduces vacancy-induced stress. Finally, atomic-resolution conductive atomic force microscopy shows a drastically more uniform current distribution due to elimination of midgap states.