Neutron irradiation defects in Czochralski silicon

In this paper the influence of neutron irradiated on the defects and oxygen precipitation in Czochralski silicon were investigated. The vacancy-oxygen complex (VO, A-center) is one of the main defects formed in neutron-irradiated Czochralski silicon (CZ-Si). In this defect, the oxygen atom shares a vacancy, it is bonded to two silicon neighbours. Annealing of the A-center in varied neutron-irradiated CZ-Si consists of two processes. The first is trapping of VO by interstitial oxygen (O-j) in low-dose neutron-irradiated CZ-Si and the second is capturing of the wandering vacancy by VO, etc, in high-dose neutron-irradiated CZ-Si. With the increase of the irradiation dose, the annealing behavior of the A-center is changed and the formation of the VO2 is depressed. It is found that V-2 and V-4 abound in high-dose irradiated CZ-Si. With the increase of the annealing temperature the monovacancy type defect is annihilated. The results show that the formation of V-4 is enhanced when the annealing temperature ran up to 400-600 degrees C and with the FTIR absorption peak at the wave number of 829 cm(-1) (VO) disappearing, five absorption peaks appear. It can be concluded that these defect-impurity complexes prolong the lifetime of positrons. It is found that the high-dose irradiated greatly accelerates the oxygen precipitation which leads to a sharp decrease of the interstitial oxygen with the increase of the annealing time. At room temperature, the 1107 cm(-1) infrared absorption band of interstitial oxygen becomes weak and broadens to low energy side. The bulk micro-defects, including stacking faults, dislocations and dislocation loops, were observed by the optical microscopy. New or large stacking faults grow up when the silicon self-interstitial atoms are created and aggregate with oxygen precipitation. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim