Vacancy effects on the formation of He and Kr cavities in 3C-SiC irradiated and annealed at elevated temperatures

Highlights: • He and Kr cavities are formed in ion-implanted and 1600 °C annealed 3C-SiC. • A higher vacancy concentration leads to formation of cavities with a smaller size and higher density. • Presence of He in irradiated 3C-SiC can significantly promote cavity growth. • Small voids are formed in Kr ion penetrated 3C-SiC during thermal annealing at 1600 °C. • Local Kr migration and trapping at cavities in SiC are observed, but long-range Kr diffusion does not occur at 1600 °C. - Abstract: Polycrystalline 3C-SiC was sequentially irradiated at 400 and 750 °C with 120 keV He²⁺ and 4 MeV Kr¹⁵⁺ ions to 10¹⁷ and 4 × 10¹⁶ cm⁻², respectively. The Kr¹⁵⁺ ions penetrated the entire depth region of the He²⁺ ion implantation. Three areas of He²⁺, Kr¹⁵⁺ and He²⁺ + Kr¹⁵⁺ ion implanted SiC were created through masked overlapping irradiation. The sample was subsequently annealed at 1600 °C in vacuum and characterized using cross-sectional transmission electron microscopy and energy-dispersive X-ray spectroscopy. Compared to the He²⁺ ion only implanted SiC, He cavities show a smaller size and higher density in the co-implanted SiC. At 25 dpa, presence of He in the co-implanted 3C-SiC significantly promotes cavity growth; much smaller voids are formed in the Kr¹⁵⁺ ion only irradiated SiC at the same dose. In addition, local Kr migration and trapping at cavities occurs, but long-range Kr diffusion in SiC is not observed up to 1600 °C.