Accumulation and recovery of irradiation damage in He + implanted α-SiC

Abstract

In situ RBS/Channeling (RBS/C) has been used to investigate damage accumulation and subsequent annealing behavior in single-crystal wafers of 6H-silicon carbide (α-SiC) irradiated at temperatures from 160 to 300 K with 390 keV He + ions to fluences ranging from 7.5 × 10 18 to 1.0 × 10 20 He +/m 2. Damage recovery in the irradiated crystals was studied by isochronal annealing at temperatures up to 1170 K. The RBS/C results show that complete amorphization in α-SiC does not occur at 190 K for irradiation fluences up to 1.0 × 10 20 He +/m 2 (0.38 dpa at the damage peak). For a fluence of 4.5 × 10 19 He +/m 2, the relative amount of damage accumulated during irradiation at 190 K is a factor of 5 larger than that accumulated under irradiation at 300 K, which suggests a higher rate of simultaneous point defect recombination at 300 K. In post-irradiation isochronal annealing studies, the integrated damage profile for all irradiated samples decreased exponentially with increasing annealing temperature. At low relative ion fluences and comparable irradiation-induced defect concentrations, the defects produced by He + irradiation at 160 K are more difficult to anneal at 300 K than those produced by Si + irradiation at 160 K, which suggests that trapping of He atoms at defects may be inhibiting recombination.