We have performed density-functional tight-binding simulations mimicking the thermal decomposition of the SiC (000 (1) over bar) surface to reproduce the experimentally observed growth of either graphene or carbon nanotubes. A graphene-like network was obtained from a layer-by-layer decomposition of the SiC surface. The interaction between graphene and SiC was found to be relatively weak. Meanwhile, carbon nanotubes grew when a five-membered ring was initially formed together with a carbon chain. The simulation results suggest that growth selectivity depends on the overall carbon network connectivity and carbon aggregation speed at the very initial stage of the decomposition process. (C) 2014 Elsevier B.V. All rights reserved.