Effect of a silicon dioxide diffusion barrier layer and its sublimation on the migration of strontium implanted into SiC

Thin film diffusion barriers are inevitable in nuclear reactors for preventing the release of radioactive waste products. The combination of chemical stable silicon carbide (SiC) and silicon oxide (SiO2) layers has been considered being beneficial, thus, we studied the migration and stability of strontium implanted SiC upon annealing, owing an additional SiO2 surface layer. Our investigations show that annealing at 1100 and 1200 degrees C retained the Sr atoms in comparison to pure SiC and induced strong strontium segregation at the SiO2/SiC interface and SiO2 surface. However, this enhanced the sublimation of the SiO2 layer, while pure SiO2 layers (i.e., without impurities) showed no sublimation after annealing under the same conditions. On the other hand, higher temperatures at 1300 and 1400 degrees C, resulted also in significant sublimation of the pure SiO2 layer.