Template-based carbon nanotubes and their application to a field emitter

Anodic aluminum oxide (AAO) templates were fabricated by anodizing Al films . After the Co catalyst had been electrochemically deposited into the botto m of the AAO template, carbon nanotubes (CNTs) were grown by the catalytic pyrolysis of C2H2 at 650 degreesC. Overgrowth of CNTs on the AAO templates was observed. The diameter of the CNTs strongly depends on the size of the pores in the AAO template. The electron field emission measurements on the samples showed a turn-on field of 1.9-2.1 V/mum and a field enhancement fac tor of 3360-5200. Our observation concerning the low turn-on field and high field enhancement factors is explained in terms of a low field screening e ffect. (C) 2001 American Institute of Physics.