PHOTOCATHODE R&D AT CORNELL UNIVERSITY*

A broad-range R&D program is pursued at Cornell University aimed at preparation and characterization of high quantum efficiency photocathodes for the Energy Recovery Linac photoinjector. The currently investigated photoemitters include both positive and negative electron affinity materials such as bi-alkali antimonides and III-V semiconductors activated with Cs and either O or F. Analysis techniques such as Scanning Auger Spectroscopy, Low Energy Electron Diffraction, Reflected High Energy Electron Diffraction and work function measurements are used to characterize the surfaces properties of the specimens. Spectral response, photoemission uniformity, electron energy distributions are used to characterize the quality of the photoelectron beam and to relate it to the measured surface properties.