Oxygen-Defect Complexes in Neutron-Irradiated Silicon

Abstract

The growth and decay of infrared absorption bands in the spectra of oxygen‐doped silicon irradiated with fast neutrons or 2‐MeV electrons at −50°C have been studied. These bands at 836, 922, 932, and 936 cm⁻¹, are associated with defect impurity complexes, and previously have been observed after electron irradiation at temperatures as low as 80°K. The gradual growth of the 836‐cm⁻¹ band, associated with an oxygen‐vacancy complex, from the low‐intensity measured immediately after neutron irradiation to approximately four times that intensity upon annealing to 275°C is in contrast with the gradual decay of the band observed after electron irradiation over the same temperature range. The growth of the band is attributed to an increase in the concentration of the O‐V complex as additional vacancies are evolved from defect clusters produced by neutron irradiation. Shifts in the annealing curves of a band at 865 cm⁻¹, which appears upon annealing above 0°C, and the band at 936 cm⁻¹ suggest that the corresponding complexes also involve vacancies. The constant intensity ratio and identical annealing behavior for the 922 and 932 cm⁻¹ bands indicate that they belong to different vibrational modes of the same complex. No shift in the annealing curves for these bands was observed for the neutron irradiated sample, suggesting that the corresponding complex does not involve vacancies but rather may involve interstitial Si atoms.