Transient luminescence of dense InAs/GaAs quantum dot arrays

Abstract

Carrier transfer between quantum dots (QDs) in very dense InAs/GaAs QD arrays is studied by means of steady state and time-resolved photoluminescence spanning a wide range of laser power from ${10}^{9}$ to ${10}^{13}$ $\mathrm{photons}/(\mathrm{pulse}\ifmmode\times\else\texttimes\fi{}{\mathrm{cm}}^{2}).$ Carrier transfer involves transitions from the ground state of small QDs into lower lying states of larger QDs, a relaxation channel that saturates at high excitation densities. The transition from saturation of the interdot carrier transfer to the unsaturated regime is identified by analyzing the temporal shape of the luminescence signal for decreasing excitation densities. The rate equation model is proposed to account the temporal evolution of photoluminescence in dense QD systems. Numerical simulations of the carrier transfer and relaxation including the interdot coupling are in good agreement with the experimental results.