Synthesis of hybrid multiwall carbon nanotubes and their enhanced field emission properties

We synthesized hybrid multiwall carbon nanotubes (CNTs) by consecutive growth with plasma enhanced chemical vapor deposition (PECVD) and thermal CVD. PECVD-grown CNTs contained the fragmented catalytic nanoparticles on their sidewalls. Subsequent thermal CVD resulted in the secondary growth of CNTs on these catalytic nanoparticles. The CNTs grown by PECVD and thermal CVD showed the turn-on electric fields of about 4.5 and 3.5 V/μm for electron emission, respectively, whereas the hybrid CNTs exhibited the low turn-on field of about 3 V/μm. Such an improvement of field emission characteristics seems to be attributed to strong field enhancement at the secondary grown CNTs.