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.