Investigation of Field Emission and Photoemission Properties of High-Purity Single-Walled Carbon Nanotubes Synthesized by Hydrogen Arc Discharge

摘要

Single-walled carbon nanotubes (SWCNTs) were directly synthesized by a hydrogen arc-discharge method by using only Fe catalyst.The synthesized carbon materials indicated high-purity SWCNTs without amorphous carbon materials from SEM observation.The SWCNTs had diameters of 1.5-2.0 nm from TEM and Raman observation.After a simple purification,TGA indicated that SWCNTs had a purity of ca.90.1 wt %.Field emission from the SWCNT emitters which were fabricated by using a spray method was measured by a diode structure.The vertically aligned SWCNT emitters showed the low turn-on voltage of 0.86 V/mu m and a high emission-current density of 3 mA/cm~2 at an applied field of about 3 V/mu m.From a Fowler-Nordheim plot,the vertically aligned SWCNT revealed a high field enhancement factor of 2.35 x 10~4.The photoemission measurements,excited by a photon energy of 360 eV,showed significantly delocalized graphite-pi:states at the purified SWCNTs.Here,we investigated that the field-emission properties of SWCNTs would be attributed to the high electronic density of states near Fermi energy,including the delocalized graphite-pi:states.