METAL-ASSISTED PATTERNED FOREST-ASSEMBLY OF SINGLE-WALL CARBON NANOTUBES

摘要

Carbon nanotubes (CNTs) are envisioned to greatly impact future science and technology particularly in the nanoscale range due to their unique one dimensional structure with tunable electrical conductivity. Thus they have received considerable attention in the development of nanodevices, field emitters and biosensors. The ability to place CNTs with controlled orientation at desired sites presents one major challenge in assembling these remarkable nanostructures into functional devices. This article reviews our present methods to fabricate uniform and patterned single-wall carbon nanotube (SWNT) forests based on Fe~(3+)-assisted self-assembly technique in which dense rope-lattice-like SWNT forests with upright direction are obtained by immobilizing carboxylated nanotubes from dimethylformamide (DMF) nonaqueous media onto the underlying substrates with the linkage of FeO(OH)/FeOCl crystallites. Since FeO(OH)/FeOCl crystallites act as linkers to bridge SWNTs onto the substrates, the appropriate placement of these iron deposits is pivotal to realize the desired SWNT patterns. To assist in localizing these FeO(OH)/FeOCl crystallites, three approaches on diverse substrates including Nafion, Si/SiO_x and Au were investigated with the aid of advanced low-energy electron-beam writing (on Nafion and Si/SiO_x) and photolithography (on Au) by creating preferential precipitation sites for FeO(OH)/FeOCl crystallites. Such differential deposition of FeO(OH)/FeOCl crystallites provided the basis for the patterned site-specific forest-assembly of SWNTs.