Nanosecond time-resolved photoluminescence (PL) and the temperature dependence of continuous wave PL from high fluence ((0.3-3) x 10(17) cm(-2)) Si-4 implanted thermal SiO2 layers after annealing at high temperature (T = 1 000 degrees C) are reported. A green-blue light and a near-infrared signal are detected; we observed a transition from the green-blue to the near-infrared signal at the critical ion fluence 1 x 10(17) cm(-2). The green-blue light emission is very fast, characterized by 0.4, 2 and 6 ns decay times, and has decreasing intensity with the increase of measurement temperature. The near infrared light signal is peaked at approximately 800 nm and has a decay time longer than 250 ns. The intensity of the near-infrared signal grows with annealing time and shows a non-monotone behaviour with measurement temperature.