Stoichiometry Control and Automated Growth of Alkali Antimonide Photocathode Films by Molecular Beam Deposition

We report on a method of photoemissive film growth that controls stoichiometry in real time. We show that stoichiometry control using a feedback loop is possible because (a) photoemissive properties exhibit a distinct dependence on the stoichiometric composition and (b) stoichiometric composition strongly depends on the ratio of the incident fluxes. The reported results were obtained on Cs3Sb but are expected to be relevant to other alkali antimonides and tellurides.