Crack-Free Growth and Transfer of Continuous Monolayer Graphene Grown on Melted Copper

Monolayer graphene with large domain sizes can be grown by chemical vapor deposition using a Cu catalyst in its molten state. However, extending this to fully continuous sheets of graphene on the centimeter scale is challenging, because of cracks, rips, and tears that are induced upon rapid cooling. The various issues that prohibit fully continuous graphene sheets are identified and solutions presented. These include (i) developing a novel two-stage CVD growth process that fills in the cracks and holes formed upon cooling; (ii) appropriate choice of underlying wetting substrate of W, instead of Mo, which causes holes; and (iii) a new electrochemical transfer method that removes W and then Cu to enable the efficient transfer of crack-free graphene sheets onto silicon wafers. Our results provide important solutions to challenges related to the synthesis and transfer of high-quality monolayer graphene grown on molten Cu catalysts for electronic applications.