The effect of annealing at <EQ 1000 K under enhanced argon pressure, HP, up to 1.6 GPa on photoluminescence, PL, and electrical properties of Cz-Si was investigated. The PL lines, related to presence of thermal donors, TDs, were detected at 2 K at (1.08 - 1.09) eV for the samples with interstitial oxygen concentration, co, in the (8 - 11) X 1017 cm-3 range, treated at 720 K - HP, whereas at 300 K the PL band at about 0.79 eV was observed. The 0.79 eV PL band intensity increased with co but decreased with HP; the treatment at HP - 720 K for 10 h of the samples with before-created TDs also resulted in decreased intensity of the 0.79 eV band PL at 0.9 eV was observed at 2 K for the sample pre-annealed at 1000 K and afterwards pressure-treated at 920 K - 1.6 GPa, whereas at 300 K, this sample indicated the broad Pl peak at 0.86 eV. Presence of `additional' defects in Cz-Si (introduced by hydrogen implantation) caused suppression of PL after annealing at 720 K -105/1.2 X 109 Pa for 10 h, whereas the hydrogen plasma etched samples indicated detectable band-to-band PL at about 1.1 eV. Qualitative explanation of observed effects was proposed.
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