IOP PUBLISHING NANOTECHNOLOGY Nanotechnology 18 (2007) 235201 (4pp) doi:10.1088/0957-4484/18/23/235201 Current-carrying capacity of double-wall carbon nanotubes Sunkyung Moon 1,2 , Woon Song 1 , Nam Kim 1 , Joon Sung Lee 1 , Pil Sun Na 1 , Soon-Gul Lee 2 , Jongwan Park 3 , Myung-Hwa Jung 4 , Hyun-Woo Lee 5 , Kicheon Kang 6 , Cheol Jin Lee 7 and Jinhee Kim 1 1 Korea Research Institute of Standards and Science, Daejeon 305-600, Korea 2 Department of Applied Physics, Korea University, Chungnam 339-800, Korea 3 National Nanofab Center, Daejeon 305-806, Korea 4 Quantum Material Research Team, Korea Basic Science Institute, Daejeon 305-333, Korea 5 Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea 6 Department of Physics, Chonnam National University, Gwang-Ju 500-757, Korea 7 School of Electrical Engineering, Korea University, Seoul 136-713, Korea E-mail: jinhee@kriss.re.kr Received 26 January 2007, in final form 15 March 2007 Published 8 May 2007 Online at stacks.iop.org/Nano/18/235201 Abstract We have studied electrical transport characteristics of individual double-wall carbon nanotubes (DWNT) under high bias voltages. As the bias voltage applied to the carbon nanotubes increases, the outermost shell of the DWNTs broke down sequentially, which enabled us to determine the current-carrying capacity of each shell. The maximum current-carrying capacity per shell was about 150 μA, which is well above that of any other previous reports. (Some figures in this article are in colour only in the electronic version) One of the potential applications of carbon nanotubes (CNTs) is an interconnect for integrated circuits due to its large current- carrying capacity, which is larger than that of copper wires (10 6 A cm -2 )[1, 2]. A metallic single-wall carbon nanotube (SWNT) has two modes for electron propagation so that the low-bias conductance of an ideal SWNT is predicted to be twice the conductance quantum (2G 0 = 4e 2 / h )[2]. However, it was observed that the current through a SWNT became saturated at high bias voltages and that the conductance was far less than the theoretically predicted value, 2G 0 [3]. It was also found that the current-carrying capacity of an individual SWNT depends on the length of the SWNT [4]. For a long SWNT whose length is longer than the electron mean free path, its current saturates in the range of 20–25 μA at high bias voltages, which was attributed to electron–phonon scattering [3]. However, the current saturation is not so clear for a short SWNT whose maximum current can be as high as 70 μA[4]. Extensive studies on I –V characteristics of CNTs at high electric fields have revealed the role of phonon and substrate [5–8]. The total current-carrying capacity of an individual MWNT is, in general, larger than that of a SWNT. The maximum current per shell, however, is in the range of 10–60 μA and depends on the length and diameter of each shell [9]. Note that such values are comparable to the maximum current-carrying capacity of a SWNT. Since the diameters of the MWNTs used in previous experiments (∼10 nm) were about 10 times larger than that of SWNTs (∼1 nm), such experimental results suggest that the diameter of the CNT is not a key factor to limit current-carrying capacity of each shell in a MWNT. It is also found that the current saturation at high bias voltage, a usual behaviour of SWNT, is not so clear or even absent in the high bias characteristics of MWNTs [9]. In this paper we report the unusually large current- carrying capacity of a double-wall carbon nanotube (DWNT). By using the electrical breakdown method [10], we have broken down each shell individually and measured the maximum current of the inner and outer shells. Both shells of DWNTs were found to be able to carry a current as high as 150 μA. We also propose a method to determine whether each shell of a DWNT is metallic or semiconducting by analysing current–voltage characteristics. High-purity DWNTs, synthesized by a hydrogen-arc discharge method [11, 12], were used in our experiments. After the dispersion of DWNTs on a Si wafer, patterns for contact 0957-4484/07/235201+04$30.00 1 © 2007 IOP Publishing Ltd Printed in the UK