PHOTOLUMINESCENCE DARK SPOT DYNAMICS IN GAAS GROWN ON SI

It was found that DSs (dark spots) observed in room temperature PLI (photoluminescence images) of GaAs grown on Si substrates moved under certain conditions. The DS dynamics in planar GaAs on Si, UCGAS (undercut GaAs on Si), undercut structures on GaAs substrates and planar homoepitaxial GaAs are measured and compared. The number of moving DSs is larger and their speed is higher in the samples with higher stress and at higher excitation. The results are consistent with the dislocation dynamics in GaAs normally seen at elevated temperature.