Enhanced annealing of implantation-induced defects in 4H-SiC by thermal oxidation

Abstract

Annealing of the prominent Z1/2 defect in 4H-SiC has been studied after thermal treatment in N2 and O2 atmospheres at 1150 °C subsequent to implantation with MeV Si-ions to doses in the range of (1–4)×108 cm−2. The annealing rate is found to be significantly enhanced under oxidizing conditions, while in N2 atmosphere Z1/2 remains stable. Hence, a substantial lowering of the annealing temperature required for defect removal in 4H-SiC doped by ion-implantation may be expected using oxidizing annealing atmosphere. Concentration versus depth profiles of Z1/2 clearly show that it is annihilated by defect species injected from the SiO2/4H-SiC interface during oxidation. The injection rate of the in-diffusing species is found to be about (1.2±0.2)×106 cm−2 s−1, and the concentration ratio of the injected species relative to the native atoms originally present in the oxidized volume is ∼1×10−7. A model where the annihilating species are injected from the surface with a diffusion coefficient of about 10−8 cm2/s yields excellent agreement with the experimental data.