Enhanced electron field emission from carbon nanotubes irradiated by energetic C ions

In this paper, the investigation on the electron field emission enhancement from carbon nanotubes irradiated by energetic C ions are reported. Multiwalled carbon nanotube arrays (MW-CNTAs) are synthesized on (100) silicon substrates by a thermal chemical vapor deposition (TCVD) at 750°C for 30 min. In this procedure, a Fe thin film with a thickness of 5 nm is used as a catalyst, and the mixing of hydrogen and acetylene with a H₂/C₂H₂ flow rate ratio of 3.3:1 is used as a reactive source. Energetic C ion irradiation is carried out by MEVVA ion implanter. The incidence angle of the ions is about 45°, and the average energy of C ions is about 40keV. The irradiation doses are 5.6x10¹⁶, 9.6x10¹⁶, 2.3x10¹⁷, 3.4x10¹⁷ and 5.6x10¹⁷ respectively. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS) and Raman are used to characterize the structures of as-grown and the irradiated CNTs. Field emission measurement is carried out in a bipolar measurement equipment with a base pressure of 1x10^-7Pa at room temperature.