Growth of Vertically Aligned Carbon Nanotube Arrays on Al Substrates through Controlled Diffusion of Catalyst

Atomic diffusion-induced catalyst evolution affects the iron catalyst lifetime and the collective termination of VACNT growth on a metal substrate. We demonstrated that controlled catalyst diffusion in the pretreatment stage is capable of extending the iron catalyst lifetime on an aluminum thin-film substrate to allow enhanced vertically aligned carbon nanotube (VACNT) growth by a conventional low-pressure thermal chemical vapor deposition. In adopting a fast-heating pretreatment to control the catalyst loss from diffusion, catalyst lifetime was extended, leading to the VACNT growth with heights up to 65% taller than those without the diffusion control strategy. Atomic diffusion of iron catalyst along the grain boundaries of aluminum thin films was found to play a critical role in the catalyst loss mechanism. This work provides the basic understanding of catalyst diffusion control to facilitate the growth of VACNT arrays on metallic substrates for various applications such as through silicon via interconn...