Transfer‐Free, Large‐Scale Growth of High‐Quality Graphene on Insulating Substrate by Physical Contact of Copper Foil

High‐quality, large‐area, single‐layer graphene was directly grown on top of a quartz substrate by a low‐pressure chemical vapor deposition (CVD) process using Cu vapor as a catalyst. In this process, continuous generation and supply of highly concentrated Cu vapor is the key to the growth of large‐scale, high‐quality graphene. It was achieved by direct physical contact, or “touch‐down,” of a Cu foil with an underlying sacrificial SiO 2 /Si substrate, and the target quartz substrate was placed on top of the Cu foil, eventually having a quartz/Cu/SiO 2 /Si sandwich structure. To establish the reaction mechanism, a test growth was performed without the quartz substrate, which revealed that Cu is diffused through the SiO 2 layer of the sacrificial SiO 2 /Si substrate to form liquid‐phase Cu‐Si alloy that emits massive Cu vapor. This Cu vapor catalyzes thermal decomposition of supplied CH 4 gas.