Investigation of Chirality Selection Mechanism of Single Walled Carbon Nanotube
Abstract
This research involved investigation of two fundamental mechanisms of carbon nanotube (CNT) growth: chirality selection of single-walled CNT (SWCNT) and growth improvement of CNT arrays. For the chirality selection mechanism, attempts to use thin membrane TEM samples to clearly observe CNT/catalyst particle interfaces under optimized growth conditions was unsuccessful. Instead, in-situ CNT growth array experiments on rational design of catalyst layers using TEM holders showed significant advancement. This involved investigation of the effects of subsupportingSiO2 layer on the interaction between Fe particles and supporting Al2O3 layer for uniform and stable growth of CNT forests. The results show that catalyst particles with a higher number density are formed on the Al2O3 layer deposited on the sub-supporting SiO2 layer than that deposited directly on the Si(100) wafer. Based on the cross-sectional TEM images, liquid contact angle measurements, and ellipsometry analyses, the Al2O3 layer deposited on thermally grown SiO2 layer is found to have a lower porosity, resulting in a lower adhesion(higher wetting angle) between Fe and Al2O3. In addition, the sub-supporting SiO2 layer acts as a diffusion barrier to prevent the formation of a new phase with Si crystal. These factors help in maintaining a high number density of Fe catalyst particles. Therefore, in order to grow CNT forests with a high population density, it is desirable to use the SiO2 sub-supporting layer under the Al2O3 layer. In addition, in order to maintain the catalyst size and number distribution during CNT growth, a new catalyst preparation method has been developed via an Fe ion is implantation method.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 13, 2016
- Accession Number
- AD1027332
Entities
People
- Seun M. Kim
Organizations
- Korea Institute of Science and Technology