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

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Carrier density manipulation in layered transition-metal dichalcogenides (TMDs) is crucial for electronic and optoelectronic devices.
• Ionic-liquid gating (ILG) is a promising technique for tuning material properties.

Purpose of the Study:

• To investigate the effect of proton (H+) injection via ILG on molybdenum disulfide (MoS2) carrier concentration.
• To explore the potential of H+-injected MoS2 as contact electrodes in field-effect transistors.

Main Methods:

• Application of ionic-liquid gating (ILG) to inject protons (H+) into layered MoS2.
• Electrical characterization of monolayer and multilayer MoS2 before and after H+ injection.
• Fabrication and testing of MoS2 field-effect transistors using H+-injected MoS2 as contact electrodes.

Main Results:

• Proton injection resulted in nonvolatile n-type doping and a metallic state in multilayer MoS2 (electron concentration ~1.08 × 10^13 cm^-2).
• Protons were confirmed to intercalate between MoS2 layers, not substitute into the crystal lattice.
• The performance of monolayer MoS2 field-effect transistors was significantly enhanced when using H+-injected multilayer MoS2 as contact electrodes.

Conclusions:

• ILG with proton injection is an effective method for nonvolatile doping of multilayer MoS2.
• The intercalation of H+ into MoS2 layers improves contact quality and device performance.
• This study advances the understanding and application of ILG technology in TMDs.