Single-Walled Carbon Nanotube Growth with Narrow Diameter Distribution from Pt Catalysts by Alcohol Gas Source Method
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Single-Walled Carbon Nanotube Growth with Narrow Diameter Distribution from Pt Catalysts by Alcohol Gas Source Method Hiroki Kondo1, Ranajit Ghosh2,3, Shigeya Naritsuka1, Takahiro Maruyama1,2 and Sumio Iijima4,5 1 Department of Materials Science and Engineering, Meijo University, Nagoya 468-8502, Japan 2 Department of Applied Chemistry, Meijo University, Nagoya 468-8502, Japan 3 CSIR-Central Mechanical Engineering Research Institute, Durgapur-713209, West Bengal, India 4 Faculty of Science and Technology, Meijo University, Nagoya 468-8502, Japan 5 Nanotube Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565 ABSTRACT Single-walled carbon nanotube (SWCNT) growth were carried out on SiO2/Si substrates using Pt catalysts at different temperatures, from 400ºC to 700ºC, under various ethanol pressures by an alcohol gas source method, a type of cold-wall chemical vapor deposition (CVD). Raman measurements showed that the optimal ethanol pressure decreased as the growth temperature was reduced, and that SWCNTs grew even at 400ºC by optimizing the ethanol pressure to 1×10-5 Pa in a high vacuum system. Compared to the SWCNTs grown from Co catalysts, the diameters of SWCNTs grown from Pt were smaller, irrespective of the growth temperature. In addition, both the SWCNT diameter and the distribution became narrower by reducing the growth temperature and we obtained small-diameter SWCNTs of which the diameters were less than 1 nm using Pt catalysts. INTRODUCTION Since the discovery of single-walled carbon nanotubes (SWCNTs) in 1991 [1], they have been anticipated for application to various electronics devices in future, such as CNT FET (field effect transistor) and single electron transistor (SET). To fabricate SWCNT devices in a conventional LSI process, it is desirable to grow SWCNTs at low temperature under high vacuum. Thus far, we have reported SWCNT growth using Co catalysts in an alcohol gas source method, a type of cold-wall chemical vapor deposition (CVD) and succeeded in SWCNT growth at 400ºC by optimizing the growth condition [2]. Recently, by using Pt as a catalyst, we also attained SWCNT growth under an ethanol pressure of 10-3 Pa, while the SWCNT yield was larger than those grown from Co catalysts at the growth temperature of 700ºC [3]. However, for fabricating SWCNT devices using current CMOS processes, it is desirable to reduce the growth temperature below 500ºC. Further, it is also important to clarify the structural properties of SWCNTs grown from Pt for applications towards electronics devices. In this study, we carried out SWCNT growth on SiO2/Si substrates using Pt catalysts under various ethanol pressures at different temperatures. By optimizing the ethanol pressure, we succeeded in SWCNT growth even at 400ºC. In addition, the SWCNTs grown from Pt catalysts show fairly small diameters with narrow distributions. This indicates that Pt catalyst is suitable for SWCNT growth for electronics applications.
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EXPERIMENTAL PROCEDURE
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