Helium assisted migration of silver implanted into SiC

Abstract

The effects of helium (He) in the migration behaviour of silver (Ag) implanted into polycrystalline siclicon carbide (SiC) was investigated. Polycrystalline SiC wafers were first implanted with Ag ions of 360 keV to a fluence of 2 × 1016 cm−2 at room temperature (RT) followed by He ions of 17 keV to a fluence of 1 × 1017 cm−2 also at RT (Ag &He–SiC), all under vacuum. The Ag&He–SiC samples were then annealed at 1100 °C for 5 h under vacuum. The Ag&He–SiC and annealed samples were characterized by transmission electron microscopy (TEM), Raman spectroscopy and elastic recoil detection analysis (ERDA). The results of this study were compared with published results of Ag-only implanted SiC, which was then annealed at 1100 °C for 5 h. Nanosized He bubbles in the amorphized SiC around the projected range of the implants were observed in the Ag&He–SiC samples. Annealing the Ag&He–SiC at 1100 °C caused appearance of cavity network mostly parallel to the surface but sometimes branching into the bulk and the surface. No migration of implanted Ag was observed in Ag-only implanted SiC while Ag migrated towards the surface and the bulk in Ag&He–SiC samples after annealing at 1100 °C. We therefore conclude that helium bubbles have a role in the migration of Ag implanted in SiC.