Ultrafast carrier capture in charged InAs quantum dots

We report theoretical and experimental results of our investigation on carrier capture and relaxation processes in undoped and modulation-doped InAs/GaAs self-assembled quantum dots (QDs). We find that carrier capture and relaxation in the ground state is faster in the modulation-doped quantum dots compared to the case in neutral dots at an excitation level as low as one electron–hole pair per dot. The ultrafast photoluminescence (PL) transient rise time observed in the charged dots is attributed to the relaxing of strained field induced by the presence of cold carriers in the dots. The Hamiltonian of electron’s interaction with local vibrating field and carrier capture time are also calculated.