Atomistic-Scale Simulations of the Graphene Growth on a Silicon Carbide Substrate Using Thermal Decomposition and Chemical Vapor Deposition

Molecular
dynamics (MD) studies of graphene growth at the atomistic
level can provide valuable insight for understanding its growth mechanism,
which is helpful to optimize the growth conditions for synthesizing
high-quality, large-scale graphene. In this work, we performed nanosecond
timescale MD simulations to explore the graphene growth on a silicon
carbide (SiC) substrate with the use of a newly developed ReaxFF reactive
force field. On the basis of simulation results at various temperatures
from 1000 to 3000 K, we identify the optimal temperature at which
the high-quality graphene might be produced. Based on this, we further
studied the graphene growth with the silicon thermal decomposition
method, and we propose different growth mechanisms on the C-terminated
(001̅) and Si-terminated (001) SiC surfaces. We also simulated
graphene growth on the Si-facet of SiC substrate using the chemical
vapor deposition (CVD) method through sequential C2H2 addition, in which the surface catalytic dehydrogenation
reactions are included. Furthermore, the temperature effect on catalytic
efficiency is discussed. The defect and grain boundary structures
of the grown graphene with these two growing strategies are investigated
as well. We also provide detailed guidelines on how our atomistic-scale
results can assist experimental efforts to synthesize layer-tunable
graphene with different growth methods.