The carbon's solubility into copper is extremely minimal and so mostly surface area diffusion and nucleation of carbon atoms are concerned. Because of this and also the growth kinetics, the graphene thickness is restricted to predominantly a monolayer. The massive edge is that the graphene might be grown on Cu https://www.facebook.com/permalink.php?story_fbid=pfbid029zKqEVYfb1SDyhK5uN1vHY2PMjdtwswmbXzJs4kvyZo8UKLf7xhxPEisosAacav7l&id=61562415773754&__cft__[0]=AZXZzicXrDrcoFUXR62i7tAH-rEAxnPN4IYr2-kS_y2aB2kDRZRZoFP8m0tZwwgbtzQjrDKHIUcx-xbgd4E1T7GjDzQs3kaBxGSANEeCPsZA5rMmzsrET7dGnxgnC0_Nlp-Zy_WrFgEaeBdXSd79mq0ZJ7sOu14-eUaCNPJ9EVk60eNNViglRmacuvWdCuhzgGjDbB9awN0KTWcP5Uu2QZjr&__tn__=%2CO%2CP-R