A Rapid Growth of Aligned Carbon Nanotube Films and High-Aspect-Ratio Arrays LINGBO ZHU, 1 JIANWEN XU, 2 YONGHAO XIU, 1 DENNIS W. HESS, 1 and C.P. WONG 2 1.—School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332. 2.—School of Materials Science and Engineering, Georgia Institute of Technology; e-mail: cp.wong@mse.gatech.edu The remarkable properties of carbon nanotubes (CNTs) make them attractive for microelectronic applications, especially for interconnects and nanoscale devices. In this paper, we report an efficient process to grow well-aligned CNT films and high-aspect-ratio CNT arrays with very high area distribution den- sity (>1600 m -2 ). Chemical vapor deposition (CVD) was invoked to deposit highly aligned CNTs on Al 2 O 3 /Fe coated silicon substrates of several square centimeter area using ethylene as the carbon source, and argon and hydrogen as carrier gases. The nanotubes grew at a high rate of ∼100 m/min. for nanotube films at 800°C, while the nanotube arrays grew at ∼140 m/min. even at 750°C, due to the base growth mode. The CNTs were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and x-ray photoelectron spectroscopy (XPS). The results demonstrated that the CNTs are of high purity and form densely aligned arrays with controllable size and height. The as-grown CNT structures have considerable potential for ther- mal management and electrical interconnects for microelectronic devices. Key words: Carbon nanotubes, chemical vapor deposition, high aspect ratio, electron microscopy, nanomaterials INTRODUCTION Carbon nanotubes (CNTs) have attracted great in- terest due to their extraordinary structural, electri- cal, and mechanical properties, and their wide range of potential applications. 1 The CNTs can be either metallic or semiconducting, depending upon how the graphite layer is wrapped into a cylinder. 2,3 Metallic CNTs show ballistic conductivity at room tempera- ture. 4 The electronic properties of perfect multi- walled carbon nanotubes (MWNTs) are similar to those of single-walled carbon nanotubes (SWNTs), 5 due to weak coupling between the graphite cylinders (layer distance is 0.34 nm). Electrons transport ballistically (without scattering) in metallic SWNTs and MWNTs over reasonable lengths ( ∼1 m), thereby enabling CNTs to carry very high currents (>10 9 A/cm 2 ) without electromigration failure. 6 Phonons also propagate easily along the nanotubes. 5 The measured thermal conductivity of an individual MWNT at room temperature is >3000 W/m·K, 7 which exceeds the conductivity of diamond (2000 W/m·K). Based on these advantageous properties of CNTs, researchers have reported the integration of CNTs into electrical interconnect applications. 8–10 However, the resistance of a single ballistic SWNT less than 1-m long is about 6.5 k with perfect contacts, 11 while ballistic transport in MWNTs with a resistance of 12.9 k has also been reported. 12 The high resistance of an individual CNT indicates that an array of thousands of parallel CNTs will be nec- essary for interconnect applications. Previous stud- ies have demonstrated the synthesis of aligned nanotubes. For instance, CNT arrays have been syn- thesized on porous silicon substrates. 13 However, the requirement of porous substrates restricts the applications in microelectronics. Ren et al. demon- strated that large areas of aligned carbon nanotubes could be grown on glass substrates using plasma- enhanced hot filament chemical vapor deposition (CVD). 14 However, the CNTs’ area distribution den- sity is not high enough to decrease the electrical (Received July 21, 2005; accepted August 29, 2005) Journal of ELECTRONIC MATERIALS, Vol. 35, No. 2, 2006 Special Issue Paper 195