"Carbon nanotube array" usually refers to nanotubes that have been grown in alignment, perpendicular to a substrate like a forest. In this case the correct term in Spanish is "matriz de nanotubos de carbono". "Conjunto" would refer to a grouping of nanotubes, so they are not necessarily aligned or organized in a particular way. "Red" would imply that it is a network, perhaps like a cobweb.

The URLs below show an English to Spanish translation of an article about nanotube arrays from MIT's Technology Review. Hope this helps!