Humidity-controlled interactions and lifting of MoS₂ on SiO₂

Fabrication of 2D material devices under ambient conditions faces challenges from humidity-dependent interfacial interactions and doping effects due to intercalated water layers. This study explores adhesion and force dynamics for a monolayer of molybdenum disulfide (MoS₂) on silicon dioxide (SiO₂) as a function of humidity, using atomic force microscopy (AFM). At low humidity (<10%RH), capillary forces dominate due to a liquid bridge forming between the AFM tip and sample. At intermediate humidity 40%RH, an additional water layer intercalates between the MoS₂ and the SiO₂ and the capillary force model alone is insufficient to describe the tip-sample interactions. Force-distance spectroscopy reveals additional force dynamics related to MoS₂-lifting and dynamics in the intercalated water. Above 60%RH, water condenses on the MoS₂ and the capillary interactions are reduced. Understanding and identifying these interactions is crucial for optimising deposition of 2D materials under humid conditions.