Metal Deposition Using Solutions on High-Density and Well-Aligned CNTs

The preparation processes of Co-Cu and Au-Ag electrodeposited films and electroless Au films, using high-density and highly orientated CNTs on a SiC substrate, were investigated. The attachment via electrochemical reduction of PVP to the CNTs/SiC resulted in a hydrophilic CNTs surface the water contact angle reduced from 110° to 70°. After Co-Cu electrodeposition, the D-band shifted to a lower wavenumber, that indicated an increase in the mass number as Co-Cu metals deposited on the CNTS/SiC. However, the morphology of this Co-Cu electrodeposited film was not related to its hydrophilicity. The CNTs worked well as cathode electrodes because of their high conductivity. During the Co-Cu electrodeposition process, high pH and a complex agent were used. This did not affect the nucleation generation rate, however, the diffusion velocity affected the reaction velocity. Meanwhile, the Au-Ag particle sizes formed with a Pt seed layer were smaller than with the CNTs/SiC substrate. The nucleation generation rates were also different since CNTs/SiC conductivity was smaller than that of Pt. The deposition bath constitution was also thought to be connected to the deposition mechanism. Therefore, to obtain small-sized particles, a higher conductivity of CNTs was needed. Lastly, to obtain more precise metal particles, electroless Au deposition was carried out. After oxygen plasma treatment, the oxidized surface and inner CNTs were displaced by deposited Au ions. The deposition of Au, with particle size approximately 5 nm, was confirmed by TEM analysis and EDS mapping. CNTs mixed electrodeposition and electroless deposition of metals were also investigated. It was confirmed that metal nanoparticles enhanced the deposition of well aligned and high-density CNTs/SiC, with a diameter of 5 nm.