The composition of the CH4 plasma

Current Progress in the Chemical Vapor Deposition of Type-Selected Horizontally Aligned Single-Walled Carbon Nanotubes

Exciting electrical properties of single-walled carbon nanotubes show promise as a future class of electronic materials, yet the manufacturing challenges remain significant. The key challenges are to determine fabrication approaches for complex and flexible arrangements of nanotube devices that are reliable, rapid, and reproducible. Realizing regular array structures is an important step toward this goal. Considerable efforts have and are being made in this vein, although the progress to date is somewhat modest. However, there are reasons to be optimistic. Positive steps of being able to control not only the spatial location and diameter of the tubes but also their electronic type (chiral control) are being made. Two primary approaches are being exploited to address the challenges. Tube deposition techniques, on the one hand, and direct growth of the desired tube at the target location are being explored. While this review covers both approaches, the emphasis is on recent developments in the direct fabrication of type-selected horizontally aligned single-walled carbon nanotubes by chemical vapor deposition.

Selective etching of metallic carbon nanotubes by gas-phase reaction

Metallic and semiconducting carbon nanotubes generally coexist in as-grown materials. We present a gas-phase plasma hydrocarbonation reaction to selectively etch and gasify metallic nanotubes, retaining the semiconducting nanotubes in near-pristine form. With this process, 100% of purely semiconducting nanotubes were obtained and connected in parallel for high-current transistors. The diameter- and metallicity-dependent "dry" chemical etching approach is scalable and compatible with existing semiconductor processing for future integrated circuits.