Spatially Enhanced Electrostatic Doping in Graphene Realized via Heterointerfacial Precipitated Metals

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Highly-doped 2D materials are crucial for advanced electronic devices and heterostructures.
• Controlling doping in 2D materials like graphene at the nanoscale remains a challenge.

Purpose of the Study:

• To present a selective-area approach for tuning the work-function and carrier density in monolayer graphene.
• To demonstrate precise control over doping levels and types (n-type and p-type) in graphene.

Main Methods:

• Spatially synthesizing sub-monolayer metallic gallium beneath graphene via precipitation from an ion-implanted diamond-like carbon (DLC) film.
• Controlling the interfacial precipitation using annealing temperature.
• Utilizing in situ and ex situ measurements for confirmation.
• Performing theoretical studies to understand charge transfer mechanisms.

Main Results:

• Achieved spatially precise ambipolar tuning of graphene's work-function, stable at ambient conditions.
• Realized tunable charge carrier densities ranging from 1.8 × 10^10 cm^-2 (hole-doped) to 7 × 10^13 cm^-2 (electron-doped).
• Demonstrated that sub-monolayer gallium facilitates heavy n-doping in graphene.

Conclusions:

• The presented selective-area doping strategy enables precise control over graphene's electronic properties.
• This method offers a new pathway for exploring the physics and chemistry of heavily-doped 2D materials.
• The approach is extendable to other implantable elements in DLC for broader applications in 2D material research.