Nonvolatile n-Type Doping and Metallic State in Multilayer-MoS₂ Induced by Hydrogenation Using Ionic-Liquid Gating

Manipulation of the carrier density of layered transition-metal dichalcogenides (TMDs) is of fundamental significance for a wide range of electronic and optoelectronic applications. Herein, we applied the ionic-liquid-gating (ILG) method to inject the smallest ions, H+, into layered MoS2 to manipulate its carrier concentration. The measurements demonstrate that the injection of H+ realizes a nonvolatile n-type doping and metallic state in multilayer-MoS2 with a concentration of injection electron of ∼1.08 × 1013 cm-2 but has no effect on monolayer-MoS2, which clearly reveals that the H+ is injected into the interlayer of MoS2, not in the crystal lattice. The H+-injected multilayer-MoS2 was then used as the contact electrodes of a monolayer-MoS2 field effect transistor to improve the contact quality, and its performance has been enhanced. Our work deepens the understanding of the ILG technology and extends its application in TMDs.