Real time evolution of antimony deposition for high performance alkali photocathode development

The development of X-ray techniques opens new opportunities for real-time in-situ study of photocathode growth process in details. The initial ultra thin Sb films during photocathode process were investigated on multiple substrates based on different applications. The real-time X-ray scattering and post-growth X-ray reflectivity and diffraction measurement were performed and analyzed. Experiment results indicate that Sb deposition performs a phase change from amorphous to crystalline, the critical thicknesses are different on B33 float glass, Si and Mo. Two methods were applied for film thickness calculation from X-ray scattering data, and they agree well with thickness monitor result. Sb films deposited on different substrates show similar final film roughnesses. The real time x-ray study indicates that the initial Sb layer deposition process on different substrate has different structure during deposition, the optimized thickness of the initial Sb layer may varies depends on the substrate. This study also paved the road for further study of the more complex alkali metal vapor diffusion process in photocathode growth.