Carbon nanotube growth from catalytic nano-clusters formed by hot-ion-implantation into the SiO2/Si interface

We have studied growth of chirality-controlled carbon nanotubes (CNTs) from hot-implantation-formed catalytic nano-clusters in a thermally grown SiO2/Si substrate. This procedure has the advantage of high controllability of the diameter and the number of clusters by optimizing the conditions of the ion implantation. In the present study, Co+ ions with ion dose of 8 × 1016 cm−2 are implanted in the vicinity of the SiO2/Si interface at 300 °C temperature. The implanted Co atoms located in the SiO2 layer has an amorphous-like structure with a cluster diameter of several nm. In contrast, implanted Co atoms in the Si substrate are found to take a cobalt silicide structure, confirmed by the high-resolution image of transmission electron microscope. CNTs are grown by microwave-plasma-enhanced chemical vapor deposition. We have confirmed a large amount of vertically-aligned multi-walled CNTs from the Co nano-clusters formed by the hot-ion-implantation near the SiO2/Si interface.