The carbon's solubility into copper is amazingly low and thus mainly surface diffusion and nucleation of carbon atoms are involved. For that reason and also the growth kinetics, the graphene thickness is restricted to predominantly a monolayer. The large benefit would be that the graphene is often developed on Cu https://www.facebook.com/permalink.php?story_fbid=pfbid0ygWVm68Mh1ZJQ1dLdxpDjBuMP8Yyvfakp73QgWKGfcpV7RVJ9yeSp68mh2LhYrbrl&id=61562415773754&__cft__[0]=AZUPDIKb0yqG5-dT2CE3hT9KjX-oLkSfiXcz28Bs6kopRBOKX097z_9LiFCCyc98YbUzBrs8DLiYdVUrsXfIrLYE08-_9tbhkUUEm6DngblrB_OQgG2KcDXJ03sxi7f0wauDzjtTUtxW61VNZpoUG4EfLiEukM4u7U4FTqdY0Z5MwE0kTyhZtoiHpzo6wmO2IdtGWubaVGEdco8aEwtSLsLK&__tn__=%2CO%2CP-R