Gate-Assisted Programmable Molecular Doping of Epitaxial Graphene Devices

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Precise control of carrier density in graphene is essential for electronic applications.
• Epitaxial graphene on silicon carbide (SiC) presents challenges for controlled doping.
• Existing methods often require multiple doping and characterization cycles.

Purpose of the Study:

• To demonstrate a novel method for precise programming of doping levels in epitaxial graphene.
• To enable reversible control of carrier concentration using gate voltage.
• To tune the carrier density across the charge neutrality point.

Main Methods:

• Exposure of top-gated epitaxial graphene devices to nitric acid vapor prior to gate deposition.
• Utilizing applied gate voltage to modulate nitric acid-induced carrier concentration changes.
• Stabilizing the tuned carrier density by cooling the sample below 200 K.

Main Results:

• Achieved precise programming of doping levels in epitaxial graphene.
• Demonstrated reversible control of carrier concentration via gate-assisted molecular doping.
• Tuned carrier density at zero gate voltage by over 4 × 10¹³ cm^-2 across the charge neutrality point.

Conclusions:

• The developed gate-assisted molecular doping offers accurate and reversible control of carrier density in epitaxial graphene.
• This method allows tuning the charge neutrality point to a desired gate voltage.
• The achieved tuning is stable at low temperatures (< 200 K).