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| The effects of fast neutron irradiation on oxygen in Czochralski silicon (CZ-Si) was investigated systemically by Fourier Transform Infrared Spectrometer (FTIR) and The Positron annihilation technique (PAT). Through isochronal annealing, it was found that the change trend of the interstitial oxygen ([Oi]) concentration in fast neutron irradiation CZ-Si fluctuated largely with increasing temperature, especially between 500℃ and 700℃. By annealing at 600℃, the appearance of V4 exists as three-dimensional vacancy clusters causes the formation of the molecule-like oxygen clusters and more importantly these dimmers having small binding energies (0.1-1.0eV) which can diffuse more easily in the Si lattice than single oxygen atom, causing strongly the oxygen agglomeration. When annealing at temperatures up to 700℃, three-dimensional vacancy clusters were observed to disappearing, oxygen agglomeration decompose into single oxygen atom (O) that returns to interstitial site. Results from FTIR and PAT provide an insight into the nature of the [Oi] at difference temperature between 500℃ and 700℃. The discrepancy of [Oi] after short time annealing from 500℃ to 700℃ is ultimately caused by transformation of fast neutron irradiation defects. |
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| Keywords:Neutron irradiation, Irradiation defects, FTIR, Vacancy, Positron lifetime |
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