The Attempt of Using GaN(Cs) Cathodes for Photo Injectors

There are a lot of opportunities to improve the electron source quality. Especially for the high average power gun producing up to mA level of average current, the searching for the better photo cathodes is a principal challenge. Gallium nitride (GaN) is a novel III-V semiconductor with the wide band gap close to the Cs2Te. As photo emitter material, GaN has a number of interesting characteristics. It has high QE and the negative electron affinity (NEA) on its surface can be achieved only with cesium; GaN (Cs) is more robust against contamination than GaAs and multi-alkali photocathodes. Thus GaN(Cs) has the chance to be a candidate for a high average current source. In this paper, the result of the first activation experiment in HZDR and the next plan will be presented.