▎ 摘　　要

A single-crystalline graphene monolayer is grown on a Ru(0001) surface by thermal annealing of a ruthenium single crystal containing carbon. The layer is highly ordered, continuous, and exhibits perfect crystallinity, with good long-range order on the order of millimeters (see figure). These findings offer high-quality graphene layers for fundamental research as well as large-scale graphene wafers for device fabrication and integration.