Interdependency of subsurface carbon distribution and graphene-catalyst interaction

Area of Science:

• Materials Science
• Surface Science
• Nanotechnology

Background:

• Graphene synthesis via chemical vapor deposition (CVD) is crucial for electronic applications.
• Understanding graphene-catalyst interactions is key to controlling growth.
• Nickel (Ni) is a common catalyst for graphene CVD.

Purpose of the Study:

• Investigate the dynamics of graphene-catalyst interactions during CVD.
• Elucidate the relationship between carbon distribution and interaction strength.
• Provide insights into self-limiting growth and multilayer formation.

Main Methods:

• In situ, time- and depth-resolved X-ray photoelectron spectroscopy (XPS).
• Grand canonical Monte Carlo (GCMC) simulations.
• Tight-binding (TB) model.

Main Results:

• Strong graphene-Ni(111) interaction depletes near-surface carbon, leading to self-limiting growth at low pressures (10⁻⁶–10⁻³ mbar).
• Increased hydrocarbon pressure (∼10⁻¹ mbar) weakens the interaction, promoting multilayer graphene via increased near-surface carbon.
• Weakly adhered, rotated graphene growth correlates with higher initial near-surface carbon levels.

Conclusions:

• Graphene growth dynamics on Ni(111) are governed by the interplay between interaction strength and near-surface carbon concentration.
• Results offer control strategies for graphene synthesis.
• Findings are relevant for understanding carbon nanotube growth mechanisms.