Ultrafast carrier capture and relaxation in modulation-doped InAs quantum dots

Abstract

We report investigations on carrier capture and relaxation processes in undoped and modulation-doped InAs/GaAs self-assembled quantum dots (QDs) by using time-resolved spectroscopy technique with a time resolution of similar to 200 fs. We find that carrier capture and relaxation in the ground state of the charged QD are faster compared to the undoped dots even at an excitation level as low as 1x10(10) cm(-2). It is attributed to the triggering of the vibrating polarization field induced by the presence of cold carriers in the doped dots. The rate of an electron been captured by a positively charged QD is also calculated based on our proposed model. (c) 2006 American Institute of Physics.