Growth of Graphene on a Liquified Copper Skin at Submelting Temperatures

In chemical vapor deposition of graphene, crossing over the melting temperature of the bulk catalyst is an effective approach to heal the defects and thus improve the crystallinity of the lattice. Here, electromagnetic absorption (the capability of metals to absorb radiated thermal energy) yields a thin skin of liquid metal catalyst at submelting temperatures, allowing the growth of high quality graphene. In fact, a chromium film initially deposited on one side of a copper foil absorbs the thermal energy radiated from a heating stage several times more effectively than a plain copper foil. The resulting migration of the chromium grains to the other side of the foil locally melts the copper, improving the crystalline quality of the growing graphene, confirmed by Raman spectroscopy. The process duration is therefore dramatically minimized, and the crystallinity of the graphene is maximized. Remarkably, the usual annealing step is no more necessary prior to the growth which together with unlocking the direct healing of defects in the growing graphene, will unify growth strategies between a range of catalysts.