[3Ga01-10] Surface Science(SS1) Physical Property

[3Ga03] Zirconium diffusion on tungsten (100) surface of Schottky electron sources

*Soichiro Matsunaga¹, Aki Takei¹, Souichi Katagiri¹ (1. R&D group, Hitachi Ltd.)

We studied the diffusion of a Zr-O complex on a W substrate, which is one of the surface components of the Schottky electron source. The source is heated up to 1800K to lead the Zr-O diffusion to emission area at the source apex. We measured the amount of Zr on the surface by using Auger electron spectroscopy. The surface coverage of the Zr–O complex was almost constant up to 600 µm without any significant loss. However, when coverage of the Zr–O complex decreased, the observed trends changed drastically, which suggests that the balance of diffusion and evaporation cannot be described by a simple material balance equation. Additionally, the range with a saturated area of the Zr–O complex became narrower at temperatures higher than 1900 K. These features, however, varied depending on the vacuum level surrounding the sample. Based on these findings, the diffusion and evaporation model of Zr and O on the surface of the Schottky electron source is proposed.