Carrier capture and escape in ${\mathrm{In}}_x{\mathrm{Ga}}_{1-x}\mathrm{A}\mathrm{s}/\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}$ quantum dots: Effects of intermixing

We have investigated photoexcited carrier dynamics in as-grown and intermixed ${\mathrm{In}}_x{\mathrm{Ga}}_{1-x}\mathrm{A}\mathrm{s}/\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}$ quantum dots and quantum wells by time-resolved photoluminescence with subpicosecond temporal resolution. Experiments were performed at high excitation in the temperature range 60–300 K. At lower temperatures, carrier lifetime in the dots is determined by radiative recombination, while at temperatures over 150 K carrier thermal emission becomes dominant. Carrier capture into the dots was found to be fast and governed by carrier-carrier scattering. In particular, at room temperature and high-excitation intensity, the carrier capture time of 0.72 ps was observed for the intermixed dots.