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

Abstract

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.