ABSTRACT
Carbon nanotube (CNT) arrays have attracted particular interest in the recent few years because of their importance in developing novel functional devices for use as scanning probes and sensors (Keller, 1996; Kong et al., 2000), as field emitters (de Heer et al., 1995; Collins and Zettl, 1997), and in nanoelectronics (Tans et al. 1998; Frank et al., 1998; Collins et al., 1997). Ajayan et al. (1994) took the lead in producing aligned CNT arrays based on cutting thin slices of a nanotube-polymer composite. Subsequently, arrays of CNTs were prepared by using chemical vapor deposition (CVD) over catalysts embedded in mesoporous silica (Li et al., 1996), anodic porous alumina template (APAT) (Kyotani et al., 1999) or Fe-patterned porous silicon (Fan et al., 1999) above 700 °C. In addition, Rao et al. ( 1998) directly synthesized CNT arrays on quartz tube by the pyrolysis of ferrocene or ferrocene-acetylene mixtures at 1100°C. However, these synthesis temperatures are too high and unsuitable in some cases where the deforming temperature of the substrate is lower than 700 °C. For example, it is desirable to directly take the aluminum substrate of APAT as electrode for field emission, which entails the temperature for synthesizing CNT arrays on APAT to be much lower than 660 oc i.e., the melting point of metal aluminum. Therefore, the low-temperature synthesis of CNT arrays is a challenging issue and is worth exploring.
