Defect-mediated transport and electronic irradiation effect in individual domains of CVD-grown monolayer MoS2

The authors study the electrical transport properties of atomically thin individual crystalline grains of MoS2with four-probescanning tunneling microscopy.ThemonolayerMoS2domains are synthesized bychemical vapor depositionon SiO2/Si substrate. Temperature dependent measurements on conductance andmobilityshow that transport is dominated by an electron charge trapping and thermal release process with very lowcarrier densityandmobility.The effects of electronicirradiationare examined by exposing the film toelectron beamin thescanning electron microscopein an ultrahigh vacuum environment. Theirradiationprocess is found to significantly affect themobilityand thecarrier densityof the material, with the conductance showing a peculiar time-dependent relaxation behavior. It is suggested that the presence of defects in active MoS2layer and dielectric layer create charge trapping sites, and a multiple trapping and thermal release process dictates the transport andmobilitycharacteristics. Theelectron beamirradiationpromotes the formation of defects and impact the electrical properties of MoS2. Our study reveals the important roles of defects and theelectron beamirradiationeffects in the electronic properties of atomic layers of MoS2