Formation of Nanoporous Electrode on Aligned CNT Films Using Dealloying

Abstract

Eco-power systems and recyclable energy are in high demand in low-carbon societies for practical applications of power devices. In these power-device fields, there is a requirement for the development of electronic packages for the radiation of heat. Carbon nanotubes (CNTs) have high thermal conductivities, large electron mean free paths, and large maximum current densities, as compared to metals. For these reasons, the application of CNTs in semiconductor packaging and three-dimensional wires is expected. It is reported that CNTs that have high densities and are well aligned are formed by the surface decomposition of SiC, which is the substrate of the power transistor [1]. However, the contact resistance between the CNTs and the electronic circuit is high. On the other hand, metal nanoparticles have been known to possess various properties that are not present in the bulk and are expected to have applications in various fields such as electronics and biotechnology. Metal nanoparticles have achieved low melting points and high chemical reactivity. Lower temperatures for some processes are expected when using nanosized particles. Au is applied in micro/nano electrochemical systems and in biotechnology applications because it exhibits superior stability and conductivity over other metals. Dealloying is the method used to construct a nanoporous structure by the selective etching of the poor metal from a bimetal consisting of a noble metal and a base metal. We have attempted to form nanoporous structures of Au–Ag films using the electrochemical method and a low-temperature dealloying process [2]. We tried to form metal nanoparticles of Au–Ag on the CNTs to get good contact resistance by dealloying. The purpose of this study is to clarify the initial growth mechanism of the electrodeposited films and nanoporous structures on the aligned CNT films, and to propose an electrode structure with good thermal-emission characteristics.