Horizontally directional single-wall carbon nanotubes grown by chemical vapor deposition with a local electric field

Abstract

We studied the directional distribution of horizontally aligned single-wall carbon nanotubes (SWNTs) grown by thermal chemical vapor deposition (CVD) under an electric field. Electrodes formed on the sample surface were used to locally apply the electric field. We inserted spacer layers between the catalyst for the CVD and the substrate and investigated the spacer thickness dependence of the directional distribution width of the SWNTs. We found that a thicker spacer layer resulted in better alignment of the SWNTs. A sample having a 200-nm-thick spacer layer produced 7° of standard deviation along the electric field. The experimental results imply that suppression of the interaction between the substrate and the SWNT tips is important. We propose a simple model that describes this interaction during the growth. Based on this model, we explain our results and formulate a simple criterion for the experimental parameters to enable perfect controllability of the SWNTs direction.