Monovacancy type defects in fast neutron irradiated Czochralski silicon

The irradiation defects in neutron-irradiated Czochralski silicon (CZSi) were analyzed by positron annihilation spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The results show that there are the massive monovacancy-type defects (VO) and multi-vacancy-type defects (V2 and V2O) in irradiated CZSi. After heat-treatment at 200-450°C, the absorption bands at 720 and 919.6 cm-1 in measured FTIR spectra are associated with the monovacancy-type defects, and they have the same positron lifetime as VO (i.e., 290 ps). After heat-treatment at 450-600°C, the monovacancy-type is eliminated gradually, the V4-type defects are enhanced, and the concentration of the V4-type defects reaches a maximum of 70% after heat-treatment at 600°C.