The effects of helium, strontium, and silver triple ions implanted into SiC

The effects of helium (He), silver (Ag) and strontium (Sr) ions triple implanted into polycrystalline silicon carbide (SiC) were investigated. Ag ions of 360 keV were first implanted into polycrystalline SiC to a fluence of 2 x 10(16) cm(-2) at 600 degrees C, followed by implantation of Sr ions of 280 keV to a fluence of 2 x 10(16) cm(-2) also at 600 degrees C (Ag + Sr-SiC). Some of Ag + Sr-SiC samples were then implanted with 17 keV He ions to a fluence of 1 x 10(-17) cm(-2) at 350 degrees C (Ag + Sr + He-SiC). Some of the dual (Ag + Sr-SiC) and triple (Ag + Sr + He-SiC) implanted samples were annealed at 1000 degrees C for 5 h. Both dual and triple implantation resulted in the accumulation of defects without amorphization of SiC structure. Moreover, triple implantation also resulted in formation of elongated He nano-bubbles and cavities in the damaged SiC accompanied by the appearance of blisters and craters on the surface. Healing of some structural defects was observed after annealing at 1000 degrees C in both dual and triple implanted samples. Implantation of Sr caused pre-implanted Ag to form precipitates indicating some limited migration while implantation of He caused some migration of both Ag and Sr. The migration of Ag was accompanied by formation of bigger precipitates trapped in He-cavities. Annealing the triple implanted caused the migration of both Ag and Sr governed by trapping of both implanted species by cavities due to some exodiffusion of He. No migration was observed in the dual implanted samples annealed at 1000 degrees C. Hence, He bubbles assisted migration of implants and He cavities trap the implanted species.