Effect of thermal cycles on microstructure of Er₂O₃ thin film on SUS316 substrate with Y₂O₃ buffer layer fabricated by MOCVD method

Erbium oxide (Er₂O₃) and Yttrium oxide (Y2O3) are the promising materials to realize an advanced breeding blanket system because of good electrical resistivity and effective hydrogen permeation suppression. In this report, Er₂O₃ thin film fabricated via MOCVD process with the Y2O3 layer formed on SUS316 substrate before and after thermal cycles to investigate the effect of thermal cycling. Their microstructure was confirmed by SEM, AFM, TEM and STEM. The surface morphology of samples after thermal cycling has small granular structure than samples before thermal cycling and without buffer layer. According to cross sectional observation by TEM and STEM, Er₂O₃ and Y2O3 have different columnar structure, while buffer layer did not avoid diffusing elements from SUS316 substrate to Er₂O₃ layer. The thermal cycling test had not been affected to the growth direction of Er₂O₃ and Y2O3 layers, which is mostly cube-cube relationship.