Photoactive defect-related Iv luminescence line observed in layers grown by molecular beam epitaxy

Intensity of a photoluminescence line named I V observed at the near band-edge region for undoped ZnSe/GaAs is found to increase exponentially with the time duration of photoexcitation. The rise time is unexpectedly long, i.e. several hundreds of seconds under low excitation intensity and at low temperatures, and decreases with increasing excitation intensity or temperature. Experimental results lead us to suggest that the luminescence center responsible for the I V line is the Se vacancy which captured one or two electrons.