First-principles calculation of 0th-layer graphene-like growth of C on SiC(0001)

We use a first-principles approach to analyze the clustering of C atoms during the initial stage of 0th-layer graphene-like growth on SiC(0001). We started the layer with the lowest-energy hexagonal C ring and then let it grow. The growth produced pentagonal rings with a heptagonal ring in a graphene-like (penta-heptagonal) structure. We also studied the chemical potential of C atoms on SiC(0001) and revealed that the C clustering begins at a surface coverage of 0.25-0.33 atom/SiC(0001)-(1×1). Finally, we confirmed that the energetic stabilities of penta-heptagonal clusters on SiC(0001) exceed that of single C rings (7-18 atoms), the lowest-energy structure of free-standing C _7-18 clusters. Hence, the results show that SiC(0001) acts as a template for graphene-like growth.