Growth of a Single Freestanding Multiwall Carbon Nanotube on each Nanonickel Dot

摘要

Patterned growth of free-standing carbon nanotubes on submicron nickel dots on silicon was achieved using plasma-enhanced- hot-filament-chemical- vapor deposition (PE-HF-CVD). A thin film nickel grid was fabricated on a silicon wafer by standard microlithographic techniques, and the PE-HF-CVD was done using acetylene (C2H2) gas as the carbon source and ammonia (NH3) as a catalyst and dilution gas. Well separated, single carbon nanotubes were observed to grow on the grid. The structures had rounded base diameters of approximately 150 nm, heights ranging from 0.1 to 5 micrometers, and sharp pointed tips. A transmission electron microscopy (TEM) cross-sectional image clearly showed that the structures are indeed hollow nanotubes. The diameter and height depend on the nickel dot size and growth time, respectively. This nanotube growth process is compatible with silicon integrated circuit processing. Using this method, devices requiring free-standing vertical carbon nanotubes, such as scanning probe microscopy, field emission flat panel displays, etc., can be fabricated without difficulty.