Study of the impact of electrode surface roughness on the field-emission properties of solid-state structures with a nanoscale vacuum gap

The effect of the electrode surface roughness on the field-emission current in a solid-state (metal or semiconductor) structure with a nanoscale vacuum gap has been studied. It was shown that as the vacuum nanogap width decreases from 100 to 10 nm and below, the roughness of the emitting surface becomes one of the key factors determining the stability of operation and reproducibility of the current-voltage characteristics of the field-emission structure at the nanoscale. It was numerically estimated that the field-emission current in the two-electrode quasi-vacuum (air) system drastically increases with increasing maximum roughness (MR) of the emitting cathode surface at the vacuum nanogap width of 10 nm and an applied voltage of 10 V. The current amplitude rises almost 300 times with a change in MR from 0.7 to 0.9 nm in the Au-air-Au structure and about 35 times with an increase in this parameter from 0.75 to 1 nm in the Si-air-Si structure, respectively. The MR values were found at which the calculated current-voltage characteristics of the field-emission structures indicated above agree quite well with the experiment. The obtained results can be applied in the development of a technology for creating an element base of field-emission devices with a nanoscale vacuum channel.