Study of the conversion of the VO to the VO2 defect in silicon heat-treated under uniform stress conditions

Abstract

The VO defect is one of the major defects produced by irradiation in Cz-grown Si. Its presence in the infrared spectra is manifested by a localized vibration mode (LVM) band at 829 cm−1. Upon annealing, the decay of this band is accompanied by the emergence in the spectra of another LVM band at 890 cm−1 generally attributed to the VO2 defect. The annealing of the VO center is discussed in the literature by considering mainly two reaction processes in neutron irradiated material, that is, VO+SiI→Oi and VO+Oi→VO2, which could occur in parallel. There are some points, however, which cannot be explained within the above reaction scheme. In this article we report infrared, x-ray, transmission electron microscopy and selective etching investigations on the annealing behavior of the VO defect, in neutron-irradiated Cz-grown Si samples, subjected to various high temperature–high pressure (HTHP) treatments prior to the irradiation. The contribution of each of the above two reactions to the whole annealing process of the VO defect and its conversion to the VO2 defect is studied. The results are discussed by taking into account that the state of the self-interstitials, adjacent to the oxygen precipitates and the structural defects formed due to the HTHP treatment, is different for each sample because of the different treatments.