Time-resolved temperature-dependent photoluminescence spectroscopy of InGaAs/GaAs quantum well-dots
The paper presents the results of a study of dynamic properties of InGaAs quantum well-dots (QWD) embedded in a GaAs matrix carried out by time-resolved photoluminescence (TRPL) in the temperature range of 10–300 K. The time dependence of the PL shows a long region of constant signal intensity. It was attributed to the filling of all available QWD states due to the fast exchange with the matrix and the relatively long time of radiative recombination. The experimental results are consistent with the calculations performed in the rate equation model for a two-level system. It turned out that there is no need for the residual 2D quantum well to be taken into account, which is not typical for Stranski-Krastanow quantum dots, where the wetting layer plays an important role in carrier exchange processes. Nonradiative recombination can also be ignored, which indicates a high quality of the structure. By fitting the simulation results, the microscopic properties of the electron and hole states in QWDs were obtained for the first time: the radiative lifetime is 700 ps, the barriers for electron and hole in QWDs are 50 and 150 meV, respectively. Carrier capture time was found to be in the range of 10-30 ps.