Rubidium intercalation in epitaxial monolayer graphene.

Area of Science:

• Materials Science
• Surface Science
• Condensed Matter Physics

Background:

• Alkali metal intercalation of graphene is key for electronics, energy storage, and catalysis.
• Rubidium (Rb) is an understudied alkali metal intercalant.

Purpose of the Study:

• Systematically investigate Rubidium (Rb) phase formation under epitaxial monolayer graphene on SiC(0001).
• Explore the effects of Rb density and sample temperature on intercalation.
• Understand the doping and structural consequences of Rb intercalation.

Main Methods:

• Multi-technique experimental approach.
• Controlled variation of Rb density (deposition time) and sample temperature (room and low temperature).
• Annealing studies to investigate structural evolution and desorption.

Main Results:

• Revealed (2 × 2) and R30° structures of intercalated Rb between graphene and the buffer layer.
• Demonstrated strong n-type doping of graphene by Rb intercalation.
• Observed Rb diffusion, enlargement of intercalated areas, and eventual desorption upon annealing.
• Confirmed reversibility of the intercalation process up to approximately 600 °C.

Conclusions:

• Rb intercalation under graphene on SiC(0001) forms ordered structures and induces significant n-type doping.
• The intercalation process is controllable via Rb density and temperature, and is reversible.
• Findings provide insights for designing graphene-based electronic and energy storage devices.