Temperature dependent field emission behavior of carbon nanotube emitters

• Temperature dependent field emission from carbon nanotubes was investigated.
• The defective layer formed by I–V annealing caused the abnormal field emission.
• The field emission current was increased with increasing temperature.
• At high temperature, non-linear Fowler–Nordheim behavior was observed.

Vertically aligned multi-walled carbon nanotubes (MWCNTs) were synthesized on Ni-coated Si substrates by thermal chemical vapor deposition, and then, the field emission behavior of the MWCNTs were investigated with increasing temperature. Before the field emission measurements, a high voltage annealing was carried out for the emitters, which resulted in the formation of defective layer at the emitting tips. We have observed largely increased emission currents and non-linear Fowler–Nordheim (F–N) plots at high temperatures. We propose that these unusual field emission behaviors are attributed to the defective layers formed on MWCNT tips by high voltage annealing.