Study on the area ratio of Nb–Sn target for the preparation of Nb3Sn films

Abstract

Niobium is extremely important in SRF cavities because of its superconducting properties. However, there are some intrinsic limits of Nb cavities that cannot meet the requirements of future accelerators. It is therefore of utmost importance to look into materials offering SRF performances beyond niobium. Nb3Sn is the most promising material. In our work, the cathode target is cylindrical and rotatable, containing both Nb and Sn elements, which are simultaneously charged, aiming to explore the area ratios of the two elements required in the cathode target by simulation and experiments, respectively. This work will provide the basis for the subsequent Nb3Sn cathode target fabrication. In the simulation, we calculated stoichiometric ratio and sputtering yield to obtain the area ratios of Nb and Sn. In the experiment, we calculated the rotation rate of the target, deposition thickness of films on substrates and deposition rate to obtain the area ratio of Nb and Sn. In conclusion, we compared the simulation and experimental results and found that they are in good agreement. The simulation and experimental results also showed that the area ratio of Nb to Sn in the target is close to 9:1. These results lay the foundation for the subsequent Nb3Sn cathode target fabrication and multilayer deposition of Nb3Sn thin films.