Field emission properties and synthesis of carbon nanotubes grown by rf plasma-enhanced chemical vapor deposition

Plasma-enhanced chemical vapor deposition (PECVD) method was employed to grow the Fe-catalyzed carbon nanotubes (CNTs). The grown CNTs with a uniform diameter in the range of about 10–20 nm and the typical lengths beyond 1 mm resulted in a very high aspect ratio. The Raman and TEM results showed that the grown CNTs contained a large amount of carbonaceous particles and crystal defects, such as pentagon–heptagon pair defects. XPS measurement indicated that the CNTs had C–H covalent bonds. Field emission characteristics exhibited the low turn-on threshold field of 2.75 V/mm and the maximum emission current density of 7.75 mA/cm2 at 6.5 V/mm. The growth mechanism of CNTs and the effects of hydrogen plasma on their structure were discussed.