Electrical conduction of carbon nanotube forests through sub-nanometric films of alumina

We report both the growth of carbon nanotube forests and electrical conduction on W, Ti, and TiN substrates coated with an ultra-thin Al O support layer. Varying the AlO thickness, a good electrical contact and high nanotube density is possible for a 0.5 nm AlO layer as such an ultra-thin film allows tunnelling. X-ray photoelectron spectroscopy shows that, when using these non-continuous AlO films, Fe catalyst diffuses into the conducting substrates, eventually causing growth to stop. Forests grown on ultra-thin AlO are potentially useful for applications as interconnects, supercapacitors, and heat spreaders.