Distinct termination morphologies for vertically aligned carbon nanotube forests

Vertically aligned carbon nanotube forests, including single-walled nanotubes, are imaged optically as they grow in situ from cobalt/alumina catalyst using water-assisted acetylene chemical vapor deposition. Three distinct termination morphologies are identified and investigated optically and via scanning electron microscopy. Quantitative growth dynamics are extracted and show gradual deceleration and sudden termination of growth. The termination morphology is discussed in terms of the balance of forces within the forest. We speculate that sudden termination is a collective effect arising from an imbalance in these forces.