pubs.acs.org/cm Published on Web 01/13/2010 r 2010 American Chemical Society 1782 Chem. Mater. 2010, 22, 1782–1787 DOI:10.1021/cm903287u Patterned Growth of Boron Nitride Nanotubes by Catalytic Chemical Vapor Deposition Chee Huei Lee, Ming Xie, Vijaya Kayastha, Jiesheng Wang, and Yoke Khin Yap* Department of Physics, Michigan Technological University 1400 Townsend Drive, Houghton, Michigan 49931, USA Received October 27, 2009. Revised Manuscript Received December 21, 2009 For the first time, patterned growth of boron nitride nanotubes is achieved by catalytic chemical vapor deposition (CCVD) at 1200 °C using MgO, Ni, or Fe as the catalysts, and an Al 2 O 3 diffusion barrier as underlayer. The as-grown BNNTs are clean, vertically aligned, and have high crystallinity. Near band-edge absorption ∼6.0 eV is detected, without significant sub-band absorption centers. Electronic transport measurement confirms that these BNNTs are perfect insulators, applicable for future deep-UV photoelectronic devices and high-power electronics. The unique structural, mechanical, electronic, and opti- cal properties of carbon nanotubes (CNTs) have attracted tremendous research interest. 1,2 CNTs can be semicon- ducting or semimetallic, depending on their structures. The small band gap of CNTs makes them applicable for optical devices in the long visible wavelengths and near-IR regions. 3 On the other hand, boron nitride nanotubes (BNNTs) exhibit extraordinary mechanical property like CNTs because of their hexagonal boron nitride (h-BN) network, which is similar to the graphene shells on CNTs. BNNTs therefore become attractive as insulating nano- composites for mechanical and reinforcement applica- tions. In addition, BNNTs are wide band gap materials (theoretically ∼5.0 eV), which are insensitive to the num- ber of walls, diameters, and chiralities. 4 This means they are uniform in electronic properties. Theories predict that BNNTs could have tunable band gap by doping 5 or by applying the Stark effect. 6 These unique electronic proper- ties making BNNTs useful in many applications, such as deep-UV photoelectronic devices, high-temperatures, and high-power electronics. However, the synthesis of BNNTs is much more difficult as compared to that of CNTs. For example, the growth of BNNTs requires high temperatures and the growth location and growth orientation of BNNTs are still uncontrollable. These problems have prevented progressive investigation on the properties and applica- tions of BNNTs. BNNTs have been synthesized by various methods, including arc-discharge, 7 laser vaporization, 8,9 BN sub- stitution method from CNT templates, 10 chemical vapor deposition (CVD) using borazine, 11,12 induction heating boron oxide CVD (BOCVD), 13,14 ball milling, 15 com- bustion of FeN/B powders, 16 and templating polymer thermolysis. 17 Among these synthesis techniques, a signi- ficant progress has been produced by BOCVD for the mass production of multiwall BNNTs and has led to potential applications. 18,19 BOCVD requires an induc- tion furnace with specific design for achieving high growth temperature (usually 1300-1500 °C) and high temperature gradient. Si-based substrates cannot be used for the coating of BNNTs using this BOCVD approach. Recently, we show that BNNTs can be directly grown on substrates by a plasma-enhanced pulsed-laser deposition *Corresponding author. E-mail: ykyap@mtu.edu Tel: (906) 487-2900. Fax: (906) 487-2933. (1) Harris, P. J. F. 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