Growth of carbon nanotube forests on metallic thin films

Growing carbon nanotube (CNT) forests on metals for integrated circuits interconnections or active layers applications is currently a challenge. CNT forests easily develop on insulators but their growth on metallic substrates is subject to interdiffusion and wettability effects that hamper the formation of the catalyst nanoparticles. This paper reports the successful growth of dense CNT forests on some metallic layers (Mo, Ta, W, and Ir) in comparison to other metallic films (Au, Cu, and Ti) over which CNTs are hardly achieved. The CNT forests are grown by thermal decomposition of C2H2 diluted in NH3 and characterized by Raman spectroscopy and scanning electron microscopy. Stabilizing Al thin films placed between the metallic substrates and the Fe catalyst promote the formation of Fe nanoparticles. Metallic substrates, thickness of the Al stabilizer, and temperature and raise time during nanoparticles formation are all instrumental parameters in the growth and final structure of the CNT forests.