Dynamics of photoexcited carriers in GaInAs/GaAs quantum dots

We present photocurrent and time-resolved photoluminescence investigations of AlGaAs/GaInAs/GaAs structures containing GaInAs/GaAs self-assembled quantum dots. The high electrical field in those devices significantly influences carrier dynamics. The photocurrent spectra show a double peak with maxima at 1.40 and 1.47 eV (at 80 K). These maxima are clue to the GaInAs wetting layer (higher) and the quantum dots (lower). The photoluminescence spectra comprise weak excitonic luminescence from GaAs at 1.504 eV (at 80 K) and stronger and broad emission from the Ga0.4In0.6As quantum dots. At 300 K, the quantum dots emission has a lifetime of 1.1 ns and has a maximum at an energy of 1.38 eV. By analysis of both experiments, we can separate the influence of different radiative and nonradiative recombination processes. So, the tunneling rate: r(T) = 0.5 ns(-1) and the radiative recombination rate in the quantum dots: r(RQD) = 0.4 ns(-1) have been determined. The high tunneling probability (due to the influence of the built-in electric field) reveals that the tunneling effect is important for the recombination and transport processes in our structures.