Field emission from camphor–pyrolyzed carbon nanotubes

Vertically aligned nanotubes, grown on various substrates by thermal decomposition of a botanical hydrocarbon––camphor, were investigated for field emission application. In a parallel plate (∼500 μm apart) field emission device, as-grown nanotubes exhibited a turn-on field as low as 2.6 V/μm, whereas the maximum current density observed was 14 mA/cm2 at an applied field of 7.7 V/μm. Utilizing such an emission efficiency of camphor-grown nanotubes, a model field emission microscope was fabricated with isolated nanotube emitters and informative emission patterns were observed on a fluorescent screen (placed at a working distance of 1–5 cm) at low applied voltages of 300–1000 V. Presence of localized density of states corresponding to pentagonal defects at the emitter tip was identified and discussed.