Paper NS-ThP7
Synthesis and Control of Carbon Nanotubes using Diffusion Mechanism of Fe Catalyst

Thursday, October 18, 2007, 5:30 pm, Room 4C

Since electrical properties of single-walled carbon nanotubes (SWCNTs) are primarily determined by its diameter and chirality, control of diameter is the crucial issue for application of CNTs-based electronic device. Thus, the preparation of catalyst with small and uniform size is essential factor to grow the SWCNTs with narrow diameter distribution. In this work, we investigate the growth of SWCNTs with narrow diameter distribution using a sandwich-like structures (Al/Fe/Al) deposited on Si substrate by DC magnetron sputter. The Fe catalyst layer is 1nm and the Al top-layer has various thickness from 1 nm to 10 nm. All samples are pre-annealed at 800°C by furnace in Ar ambient. Then, CNTs are grown by thermal chemical vapor deposition with C₂H₂, H₂ at 850°C for 10 min. A sort of CNTs are determined using Raman spectroscopy, and after pre-annealing, the variety of catalyst size with the thickness of top-Al layer is checked by X-ray photoelectron spectroscopy, transmission electron microscopy and magnetic force microscopy. It shows that the density and the kind of CNTs are depend on the thickness of Al top-layer and pre-annealing conditions. From these results, we can consider the following: (1) The catalyst is out-diffused through the Al top-layer by pre-annealing process, and the exposed catalyst size will be controlled by the thickness of Al top-layer and the pre-annealing conditions. Thus, we can be control a sort of CNTs. (2) This technique can be used for the device application that employ SWCNTs.