Spanning the “Parameter Space” of Chemical Vapor Deposition Graphene Growth with Quantum Chemical Simulations

Abstract

Graphene is a 2-dimensional allotrope of carbon with remarkable physicochemical properties. Currently, the most promising route for commercial synthesis of graphene for technological application is chemical vapor deposition (CVD). The optimization of this chemical process will potentially enable control over crucial properties, such as graphene quality and domain size. Such optimization requires a detailed atomistic understanding of how graphene nucleation and growth takeing place during CVD. This mechanism depends on a multitude of synthetic parameters: temperature, CVD pressure, catalyst type, facet and phase, feedstock type, and the presence of chemical etchants, to name only a few. In this feature article, we highlight recent quantum chemical simulations of chemical vapor deposition (CVD) graphene nucleation and growth. These simulations aim to systematically span this complex CVD "parameter space", towards providing the necessary understanding of graphene nucleation to assist the optimization of CVD graphene growth.

Ni2Csurface carbide to catalyze low-temperature graphene growth

“…5(b) and 5(c)]. Such a mechanism has already been observed in the case of graphene growth on Ni(111) [32,36]. Interestingly, some C atoms of the carbide layer can also be integrated into the graphene network, in agreement with the two-layer mechanism proposed in [10] (typically 1-3 C atoms from the 40 C atoms of the carbide layer).…”

“…This is problematic in the present case where a theoretical study of the Ni 2 C/Ni(111) substrate to grow graphene requires large supercells and finite-temperature calculations. Semiempirical (or tight-binding) [30][31][32] and empirical [33,34] interatomic potentials are, in principle, able to meet such requirements, but their ability to deal with the complex carbide surface structure should be carefully assessed. In the general context of carbon nanotubes and graphene growth, we developed an order-N tight-binding (TB) method to describe the Ni-C system [35].…”

A free energy study of carbon clusters on Ir(111): Precursors to graphene growth

“…General trends for the cluster stability obtained here broadly agree with previous zero temperature studies. 12,18,29,30 We have shown, therefore, for the first time, that the expected sequence of cluster transitions remains the same as the temperature is raised. This result is very important, especially considering the high temperatures required for graphene growth.…”

“…12 This suggests that clusters may prefer to nucleate at step edges rather than on terraces. 15,18 Nevertheless, the actual location of nucleation has been shown to depend on experimental conditions: depositing the hydrocarbon source at low temperatures, and then heating, results in growth that begins on terraces, to be compared with depositing at high temperatures which initiates the growth at step edges. 2 This is perhaps due to the increased mobility of species at higher temperatures.…”

“…The nucleation of graphene has also been considered with kinetics simulations. Molecular dynamics 16,17,[22][23][24][25][26] and Monte Carlo 27,28 simulations (see also reviews 18,[29][30][31] ) have been performed at high temperatures in order to determine the nucleation process during the growth of graphene and carbon nanotubes (CNTs). For instance, according to one theory, 18,30 on Cu(111), Ni(111), and Fe(111) surfaces, as well as on nanoclusters, graphene networks are formed by a distinct mechanism.…”