Interpreting the field emission equation for large area field emitters

Abstract

Both single emitters and large area field emitters (LAFEs) are generally characterized using the slope and intercept of a Murphy–Good (or Fowler–Nordheim) plot, which are used to extract the field enhancement factor and the emission area. Using a shielding model that has been developed recently for a LAFE, the validity of the underlying assumption is investigated. It is found that in the case of a LAFE, the slope has contributions from the enhancement factor as well as the rate at which the effective number of superemitters changes with the applied field. As a consequence, the emission area is related to both the slope and intercept in a LAFE. When the mean spacing in a LAFE is much larger than the height of the emitter, the usual interpretation of the slope and intercept is recovered.