Ultra-sensitive humidity sensors based on a MoS₂/graphene Schottky diode

The exceptionally high specific surface area of two-dimensional (2D) materials has significantly promoted the development of 2D thin-film-based electronic devices for gas and humidity sensing. This work demonstrates an ultrasensitive electronic humidity sensor based on a monolayer MoS₂/monolayer graphene Schottky diode. Within the relative humidity (RH) range of 15% to 55%, the MoS₂/graphene Schottky diode based humidity sensor exhibited a remarkable responsivity (ΔR/R₀) of approximately 1131.1%, which was three orders of magnitude higher than those of humidity sensors based on monolayer graphene (1.98%), graphene/MoS₂ heterostructures (1.69%), and MoS₂/graphene heterostructures (1.16%) and was over four times higher than that of monolayer MoS₂ based sensors (271.1%). The ultra-sensitive humidity sensing mechanism was attributed to the modulation of the built-in electric field within the MoS₂/graphene Schottky diode by adsorbed water molecules. These findings provide valuable insights for promoting the development of 2D material-based electronic devices in humidity sensing applications.