Molecular Doping of Multilayer ${\rm MoS}_{2}$ Field-Effect Transistors: Reduction in Sheet and Contact Resistances

For the first time, polyethyleneimine (PEI) doping on multilayer MoS₂ field-effect transistors is investigated. A 2.6 times reduction in sheet resistance and 1.2 times reduction in contact resistance have been achieved. The enhanced electrical characteristics are also reflected in a 70% improvement in ON-current and 50% improvement in extrinsic field-effect mobility. The threshold voltage confirms a negative shift upon the molecular doping. All studies demonstrate the feasibility of PEI molecular doping in MoS₂ transistors and its potential applications in layer-structured semiconducting 2-D crystals.