Kinetically determined shapes of grain boundaries in CVD graphene

Abstract: Predicting the shape of grain boundaries is essential to control results of the growth of large graphene crystals. A global energy minimum search predicting the most stable final structure contradicts experimental observations. Here we present Monte Carlo simulation of kinetic formation of grain boundaries (GB) in graphene during collision of two growing graphene flakes. Analysis of the resulting GBs for the full range of misorientation angles $\alpha$ allowed us to identify a hidden (from post facto analysis such as microscopy) degree of freedom - the edge misorientation angle $\beta$. Edge misorientation characterizes initial structure rather than final structure and therefore provides more information about growth conditions. Use of $\beta$ enabled us to explain disagreements between the experimental observations and theoretical work. Finally, we report an analysis of an interesting special case of zero-tilt GBs for which structure is determined by two variables describing the relative shift of initial islands. We thereby present analysis of the full range of tilt GB ( $\beta\neq$ 0) and translational GB ( $\beta$ = 0). Based on our findings we propose strategies of controlling the GB morphology in experiments, which paves the way to a better control over graphene structure and properties for advanced applications.