Growth of Carbon Nanotubes on Diamond with a Robust Structural Connection via Microwave Plasma Chemical Vapor Deposition

In this paper, we present a novel method for growing carbon nanotubes (CNTs) via microwave plasma chemical vapor deposition (MPCVD) on diamond and silicon substrates. Scanning electron microscopy (SEM) and Raman spectroscopy analyses revealed dense, multi-walled carbon nanotubes growing on the diamond substrate. Optical Emission Spectroscopy (OES) showed that in the process of growing carbon nanotubes with the MPCVD method, the CH4 introduced into the system is excited by microwaves and dissociated to form active radicals such as C2 and CH, which are considered the C source of the synthesized carbon nanotube. Observation with high-resolution transmission electron microscopy (HRTEM) showed that most Ni catalyst nanoparticles that catalyze the growth of carbon nanotubes are located close to the diamond surface. In contrast, on the Si substrate, Ni catalyst nanoparticles were randomly distributed. A unique transition layer was observed between the diamond and carbon nanotubes, with the Ni particles being immersed into this transition layer and acting as anchors to fix the carbon nanotubes, resulting in a robust connection between the diamond and the CNT coating.