Lifetime Control in Irradiated and Annealed Cz n-Si: Role of Divacancy-Oxygen Defects

摘要

The behavior of the nonequilibrium charge carrier lifetime (tau) in Czochralski-grown (Cz) n-Si after a low-dose Co-60 gamma or 1 MeV electron irradiation and subsequent annealing are investigated. Irradiated samples with different doping levels (free-electron concentration n(0) approximate to 10(14)-10(16) cm(-3)) are isochronally annealed at temperatures between 20 and 380 degrees C. It is found that tau significantly decreases after annealing in the range approximate to 180-280 degrees C, and this effect is stronger in low-resistivity n-Si. It is shown that change in tau in the annealing range of 180-380 degrees C is caused by the divacancy-oxygen (V2O) complexes. The Shockley-Read-Hall (SRH) theory is used to describe the experimental data. It is determined that the V2O formation is characterized by the activation energy of 1.24 +/- 0.04 eV and the frequency factor of (1 +/- 0.5) x 10(9) s(-1), and their annealing is characterized by the activation energy of 1.54 +/- 0.09 eV and the frequency factor of (2.9 +/- 0.6) x 10(10) s(-1). The values of hole capture cross-section (sigma(p)) by the single- and double-charged acceptor states of V2O are obtained as (5 +/- 2) x 10(-13) and (8 +/- 4) x 10(-12) cm(2), respectively.