Evaluation of field emission parameters in a copper nano-tip based diode

摘要

Copper nano-tip based diode structure with a gap of ～120 nm has been fabricated by milling of a thin metallic film with a 30 kV focused gallium ion beam at a current of 100 pA. Its current-voltage characteristics measured at a pressure of ～10~(-6) mbar is shown to follow the Fowler-Nordheim (F-N) field emission tunneling above ～40 V. A simple method has been proposed to evaluate parameters like effective area (A_(eff)), apparent work function (?), and field enhancement factor (β) of the nano-emitter. The extremely small A)_(eff), substantial lowering of ?, and high [i value observed have been explained in terms of changes occurring at the emitter tip with increasing applied field. The formation of metallic nanoparticles over the substrate by local evaporation of cathode material at high currents is also demonstrated.