Preferential Growth of Semiconducting Single-Walled Carbon Nanotubes on Substrate by Europium Oxide.

In this paper, we have demonstrated that europium oxide (Eu(2)O(3)) is a new type of active catalyst for single-walled carbon nanotubes (SWNTs) growth under suitable conditions. Both random SWNT networks and horizontally aligned SWNT arrays are efficiently grown on silicon wafers. The density of the SWNT arrays can be altered by the CVD conditions. This result further provides the experimental evidence that the efficient catalyst for SWNT growth is more size dependent than the catalysts themselves. Furthermore, the SWNTs from europium sesquioxides have compatibly higher quality than that from Fe/Mo catalyst. More importantly, over 80% of the nanotubes from Eu(2)O(3) are semiconducting SWNTs (s-SWNTs), indicating the preferential growth of s-SWNTs from Eu(2)O(3). This new finding could open a way for selective growth of s-SWNTs, which can be used as high-current nanoFETs and sensors. Moreover, the successful growth of SWNTs by Eu(2)O(3) catalyst provides new experimental information for understanding the preferential growth of s-SWNTs from Eu(2)O(3), which may be helpful for their controllable synthesis.