Interdependency of Subsurface Carbon Distribution and Graphene–Catalyst Interaction

Abstract

The dynamics of the graphene–catalyst interaction during chemical vapor deposition are investigated using in situ, time- and depth-resolved X-ray photoelectron spectroscopy, and complementary grand canonical Monte Carlo simulations coupled to a tight-binding model. We thereby reveal the interdependency of the distribution of carbon close to the catalyst surface and the strength of the graphene–catalyst interaction. The strong interaction of epitaxial graphene with Ni(111) causes a depletion of dissolved carbon close to the catalyst surface, which prevents additional layer formation leading to a self-limiting graphene growth behavior for low exposure pressures (10–6–10–3 mbar). A further hydrocarbon pressure increase (to ∼10–1 mbar) leads to weakening of the graphene–Ni(111) interaction accompanied by additional graphene layer formation, mediated by an increased concentration of near-surface dissolved carbon. We show that growth of more weakly adhered, rotated graphene on Ni(111) is linked to an initially higher level of near-surface carbon compared to the case of epitaxial graphene growth. The key implications of these results for graphene growth control and their relevance to carbon nanotube growth are highlighted in the context of existing literature.

Probing the role of carbon solubility in transition metal catalyzing single-walled carbon nanotubes growth

“…Local densities of electronic states are calculated using a recursion method, where the first four continued fraction coefficients only are calculated exactly. Applications of this model to the catalytic growth of graphene and carbon tubes have already been presented elsewhere 9,28,29 , showing the relevance and robustness of this model. A further advantage of our TB model is that it can be fairly easily generalized to other metal-carbon systems since we know qualitatively how the different parameters (transfer integrals, atomic energy levels, etc...) vary with the nature of the metallic element.…”

“…By combining MC simulations, DFT-based calculations and in-situ X-ray photoelectron spectroscopy, we could evidence this depletion effect and revealed an interdependency between the carbon distribution close to the catalyst surface and the strength of the graphene-Ni interaction. Epitaxial graphene formation on Ni(111) leads to a depletion of carbon close to the Ni surface 29 . In the present situation, this effect leads locally to the interaction of graphene with pure NP which depends on the metal-carbon interaction.…”

2D-MTJs: introducing 2D materials in magnetic tunnel junctions

“…Typically, the CVD processes on Ni or Co were known to give rise to multilayers being grown. The parameter space of these processes has only recently been investigated by in situ x-ray photoelectron spectroscopy (XPS) measurements during CVD growth, allowing careful understanding of the mechanisms at play [18,49]. Usually, growth is enabled at temperatures >600 °C, but a fine tuning of the processes allowed the growth to be limited to a monolayer and the temperature to be lowered down to 450 °C and below (thus compatible with the usual CMOS processing) [18,50].…”

Oxygen-activated growth and bandgap tunability of large single-crystal bilayer graphene

“…Oxygen is required for dehydrogenation of CH x so that atomic C can diffuse through the Cu foil for the 2 nd layer growth on the exterior surface. In other words, O opens up the kinetic pathway for BLG growth, a critical aspect that has been up to now completely overlooked [7][8][9][10][11][12][13][14][15][16][17][18][19] .…”