Time dependent emission from coated metals and semiconductors

Photoemission predictions are often based on a Three Step (absorption, transport, emission) model. The transport calculation therein generally assumes that scattering events are fatal to electron emission. Using Monte Carlo and material dependent scattering terms for metals and semiconductors, the “fatal approximation” is assessed. Photoemission data from cesiated tungsten dispenser photocathodes is reexamined with respect to the new models. The emitted current is segregated into two groups: electrons which do not scatter before emission and those that do. Each has a characteristic time response for which simple models are developed. A simple extension to semiconductors will be proposed in the presentation.