Codeposition of ultrasmooth and high quantum efficiency cesium telluride photocathodes

Cesium telluride (CsTe) photocathodes have been the primary choice for electron sources by worldwide accelerators, due to their high quantum yield, stable performance in complex operation environments and long lifetime. In this paper we compared the traditional sequential and the newly developed coevaporation growth of CsTe photocathodes by describing the chemical and structural evolution of each growth method, using in situ, real time x-ray characterization. From the codeposition method, we were able to achieve similar to 2 nm surface roughness, high crystallinity and a quantum efficiency of 19% at 266 nm wavelength.