MAGNETIC MESUREMENT OF NONMAGNETIC CATALYZED SWNTs
Zohreh Ghorannevis 1, Toshiaki Kato 2 , Toshiro Kaneko 2, Rikizo Hatakeyama 2
1 Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran, Iran
2 Department of Electronic Engineering, Tohoku University, Sendai 980-8579, Japan
Abstract. One dimensional single-walled carbon nanotubes (SWNTs) are potential materials for future nanoelectronics. Since the electronic and optical properties of SWNTs strongly depend on their diameter and chiral angle, the selective synthesis of SWNTs with desired chiralities is one of the major challenges in nanotube science and applications. Some progress has been made by silica supported CoMo and zeolite supported FeCo catalysts. FeRu and FeNi catalysts have also been developed for narrow chirality distribution. Noticeably, all of these results on the narrow chiraity distribution growth have been limited to the case of using magnetic catalysts. In spite of recent improvements in the SWNTs growth with nonmagnetic catalysts, the diameter and chirality (n,m) distribution control with the nonmagnetic catalysts is still highly required for the variety of applications. Here we demonstrate a narrow-chirality distributed growth of SWNTs from an Au catalyst. The chirality and diameter distribution is analyzed by photoluminescence excitation/emission (PLE) spectroscopy, UV-vis-NIR absorption spectroscopy, and Raman scattering spectroscopy with multi-lasers excitation. Based on the systematic investigation using the different combinations of catalyst types (magnetic or nonmagnetic) and chemical vapor deposition (CVD) methods (thermal CVD (TCVD) or plasma CVD (PCVD)), PCVD with the nonmagnetic catalyst under an appropriate H2 concentration is found to be critical. Electrical characteristics of thin films consisting of SWNTs produced under the different combinations of catalyst types and CVD methods are also investigated, which indicates the SWNTs grown from the nonmagnetic catalyst with PCVD show the best device performance. We have for the first time demonstrated the selective growth of (6,5) rich SWNTs from the nonmagnetic catalyst. This narrow-chirality distributed SWNTs selectively grown from the nonmagnetic catalyst could be attractive to both fundamental studies of intrinsic magnetic properties of SWNTs and industrial applications to nanoelectronics.
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