Fabrication of YH3 thin film using Pd/Ni co-capping layer: Ni thickness effect

Abstract With an aim of decreasing the temperature at which metallic Y reacts with H 2 to form the semiconductor phase YH 3 ( γ phase), we employed Pd and Ni co-capping layers as catalysts. For this purpose, various types of Pd/Ni co-capping layers having different Ni thicknesses varied from 5 to 80 nm while having a Pd thickness of 80 nm were prepared as a catalytic capping layer on metal Y. We achieved an onset temperature ( 50 ° C ) of the γ phase formation, which is approximately independent of Ni thickness except for 40 nm. A directing principle for decreasing the onset temperature of the γ phase formation was discussed in terms of crystal texture and crystallite size of dihydride phase ( β phase).