(A) study of branching structure on Metal Doped Carbon Nitride Nanotubes and its field emission properties

Abstract

Nanometer scale electronic devices have been attracting more attentions in miniaturization process in recent decades. Particularly, carbon nanotubes, which have unusually structure and electronic properties, are considered as excellent candidates in nanotechnology such as junctions, transistors and emitters. Further, beside linear architecture, multi-terminal carbon nanotubes were proved to be novel frameworks in microelectronics for their 2-D stem-branch configuration and also regarded as reliable field emission materials. However, the fabrication of carbon nanotubes with multi-branches remains a challenge because some of the key parameters (length, diameter, direction, etc) are still out of control. In this study, a two-step multi-branching carbon nanotube synthesis method has been successfully established in which the branch characteristics including diameter, number of walls, composition, direction and length have been well adjusted by tuning the conditions during preparation, namely, the stem nanotubes and branch nanotubes were produced separately. The stems were carbon nitride nanotubes doped by transition metal atoms which act as substrates and catalysts and the branches were actually the secondary nanotubes growth on the stems by micro plasma enhanced chemical vapor deposition. It was experimentally demonstrated that the field emission based on this branched carbon nanotubes was enhanced, and several critical factors were found to affect their field emission behavior efficiently. The $Fe_3$ $O_4$ nanoparticles doped carbon nanotubes were synthesized by a simple chemical approach with the incorporation of nitrogen. Since the defects on the carbon nanotubes play a significant role in the interaction of transition metal and carbon nanotubes, nitrogen atoms were induced into carbon nanotubes to make defects so as to enhance the $Fe_3$ $O_4$ doping ability. Experiment results showed $Fe_3$ $O_4$ nanoparticles with a narrow size distribution were unif...