Catalytic Growth of Multi-walled Carbon Nanotubes by IPC-CVD and Their Field Emission Properties

Abstract

The metals nickel (Ni) and cobalt (Co) are deposited on TiN/Si substrates by RF magnetron sputtering and employed as catalysts for carbon nanotubes (CNTs). The effects of both catalysts on the structural and electron-emission properties of CNTs are investigated. CNTs are grown by inductively coupled plasma chemical vapor deposition (ICP-CVD) using a gas mixture of NH3 and C2H2. The scanning electron microscopy (FESEM) analysis shows that Ni catalyst grains are easily agglutinated after the NH3 treatment, whereas this is not the case with the Co catalyst grains. Raman spectroscopy was used to analyze the graphitic structures and crystal qualities of CNTs. In addition, the electron-emission characteristics of diode-type field emitters show that at an identical electric field of 5.5 V/μm the maximum emission current density is higher for the CNTs grown on Ni catalysts (11.67 mA/cm2) rather than those grown on Co catalysts (1.5 mA/cm2).