Subsurface Carbon Incorporation Controls Graphene Nucleation on Ir(111).

Area of Science:

• Materials Science
• Surface Science
• Nanotechnology

Background:

• Two-dimensional (2D) material growth via chemical vapor deposition (CVD) involves complex surface processes.
• On transition metal surfaces, adatom dissolution into the bulk adds a critical parameter.
• Understanding nucleation is key for controlling 2D material synthesis.

Purpose of the Study:

• To investigate the nucleation density and scaling behavior of graphene islands on Ir(111).
• To analyze the impact of temperature and dosing pressure on nucleation.
• To elucidate the role of bulk dissolution in graphene island formation.

Main Methods:

• Low-energy electron microscopy (LEEM) was used to observe graphene nucleation.
• Kinetic Monte Carlo (KMC) simulations were performed to model the growth processes.
• Experiments varied temperature and dosing pressure to study nucleation regimes.

Main Results:

• Graphene nucleation density on Ir(111) exhibited two distinct pressure-dependent regimes.
• At low pressures, nucleation was suppressed, consistent with incomplete condensation.
• At higher pressures, bulk dissolution became negligible, increasing nucleation density and altering scaling exponents.

Conclusions:

• Bulk dissolution significantly impacts 2D material nucleation on transition metals.
• A universal, temperature-independent scaling law governs nucleation, with a crossover reflecting finite solubility.
• This provides insights into generic nucleation behavior for 2D materials.