Carbon nanotubes and ZnO based functional coaxial heterostructured nanotubes have been fabricated by using atomic layer deposition. An irregular structured shell composed of ZnO nanocrystals was deposited on pristine nanotubes, while a highly defined ZnO shell was deposited on the tubes after its functionalization with Al₂O₃. Photoluminescence measurements of the ZnO shell on Al₂O₃/nanotube show a broad green band emission, whereas the shell grown on the bare nanotube shows a band shifted to the orange spectral range.