Enhanced Backgate Tunability on Interfacial Carrier Concentration in Ionic Liquid-Gated MoS₂ Devices

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Ionic liquid-gated devices exhibit periodic spatial modulation potentials due to ion distribution, similar to nanopatterning.
• The coupling between modulation potential and carrier concentration in these devices has limited their application.
• Exploring independent control over these factors is crucial for novel device functionalities.

Purpose of the Study:

• To demonstrate the decoupling of periodic modulation potential and carrier density in ionic liquid-gated devices.
• To investigate the role of a conventional backgate in achieving this decoupling.
• To enable new functionalities by overcoming inherent limitations in ionic liquid gating.

Main Methods:

• Utilizing a conventional backgate in conjunction with ionic liquid gating.
• Applying large gate voltages to induce periodic spatial modulation.
• Analyzing carrier concentration tunability through backgate modulation and bulk channel-mediated tunneling.

Main Results:

• Successfully demonstrated the feasibility of decoupling periodic modulation potential and carrier density.
• The backgate provided comparable tunability of carrier concentration to ionic gating, especially at high ionic liquid gate voltages.
• Bulk channel-mediated back tunneling was identified as the mechanism for this control.

Conclusions:

• Decoupling periodic potential modulation and carrier density is achievable in ionic liquid-gated devices using a backgate.
• This approach overcomes a significant hurdle, paving the way for advanced device designs.
• Independent control offers new avenues for exploring functionalities analogous to nanopatterning and moiré engineering.