Origin of secondary-electron-emission yield-curve parameters

Abstract

From an analysis of the one‐dimensional constant‐loss theory of secondary electron emission, maximum yield (δ_m), primary electron energy at maximum yield (E_om), and both crossover energies E^I_oc and E^II_oc are shown to depend on the surface and bulk properties of the emitting material through simple relations. In particular, the results strongly suggest that the first crossover energy can be very dependent on surface properties, whereas the energy at maximum yield is entirely controlled by bulk properties. Refinement of the low‐energy part of the reduced yield curve by means of the results of the more realistic three‐dimensional theory leads to the development of the expression E^I_oc=0.51E_omδ_m^−1.32. Comparison between theory and experiment for several secondary‐emitting materials is presented to demonstrate the accuracy of this useful relation. Finally, the implications of these results for different classes of materials are discussed in terms of basic physical properties, such as density, electrical conductivity, work function, and band gap.