Comparative study of resonant and sequential features in electron field emission from composite surfaces

• The relationship between resonant and sequential field emission is studied.
• Sequential current–voltage characteristics show barrier-controlled undulations.
• Resonant characteristics depend mainly on the width/shape of the topmost well.
• The resonant and sequential total energy distributions differ widely.

A simple model of a layered hetero-structure was developed and used to simultaneously compute and compare resonant and sequential electron field emission currents. It was found that, while various slope changes appear in both current-field characteristics, for the sequential tunneling type of emission, such features are merely interference effects. They occur in parts of the structure, prior to the electrons' lingering in the quasi-bound states from which field emission proceeds. These purely quantum effects further combine with the flow effects resulting from the steady current requirement and give corresponding field variations of the electron population of the quasi-bound states, which further react on the resonant part of the current. A spectral approach of the two types of field emission is also considered by computing the total energy distribution of electrons in each case. The differences between these possible spectra are pointed out and discussed.