Theory of emission noise from silicon field emitters

A calculation is made of the spectral density of emission fluctuations for silicon emitter tips for two emission mechanisms: emission mainly from surface states, and emission mainly from the conduction band edge. In both cases surface-state occupancy fluctuations, calculated from the generalized Nyquist formula, modulate the field emission current. The basic idea is that emission is likely to come from either surface states or from carriers in the conduction band, or both. If there are generation-recombination (G-R) fluctuations in the surface states at the emission surface, then there will be corresponding fluctuations from surface states. This G-R noise will also cause fluctuation in carrier concentrations in the emission area, and hence noise in emission from the conduction band. A discussion is given of whether the differing spectral densities for these two mechanisms may be compared with measurements to clarify which mechanism is dominant