Investigation of lanthanum contamination from a lanthanated tungsten ion source

Tungsten is a material with distinctive advantages when used for ion sources, such as chemical resistance against common source feed gases or the very high melting point. In comparison to molybdenum, tungsten shows less sputter erosion and no obvious mass interference when BF₂⁺ is implanted. However, the machinability of pure tungsten is very poor. WL 10 is an alloy of tungsten and 1% La₂O₃ that combines the advantages of pure tungsten with a significantly increased machinability. In this paper, the contamination potential of lanthanum for B⁺, BF₂⁺, P⁺, and As⁺ implants, respectively, was studied by means of simulations and experiments.