Temperature and excitation power dependence of the optical properties of InAs self-assembled quantum dots grown between two Al0.5Ga0.5As confining layers

We have investigated the temperature and excitation power dependence of photoluminescence properties of InAs self-assembled quantum dots grown between two Al_0.5Ga_0.5As quantum wells. The temperature evolutions of the lower- and higher-energy transition in the photoluminescence spectra have been observed. The striking result is that a higher-energy peak appears at 105 K and its relative intensity increases with temperature in the 105–291 K range. We demonstrate that the higher-energy peak corresponds to the excited-state transition involving the bound-electron state of quantum dots and the two-dimensional hole continuum of wetting layer. At higher temperature, the carrier transition associated with the wetting layer dominates the photoluminescence spectra. A thermalization model is given to explain the process of hole thermal transfer between wetting layer and quantum dots.