Fig. 5: Graphene nanoribbons (GNRs) on the semi-molten Cu substrates at different temperatures.

a–c 1200 K, d–f 1350 K and g–i 1450 K. GNR-3, GNR-5, and GNR-8 represent the ribbons with 3, 5, and 8 rows of hexagonal rings along the width direction, respectively. The Cu atoms of the metal step are highlighted in yellow.