Carrier dynamics of single InAs quantum dots in a high density sample

Abstract

Summary form only given. There is inhomogeneous broadening due to fluctuations in size, strain, and composition in quantum dot (QD) ensembles. To overcome that single QDs spectroscopy has been done using low density samples. But the typical density of self-assembled InAs/GaAs QDs is high. It was shown that the carrier relaxation in QDs is strongly dependent on the carriers in the surrounding wetting layer. In high density QD ensembles the photoluminescence (PL) rise time is very small (<40 ps). But in low density single QDs there is delay as long as 2 ns, and it increases with excitation power. To solve this puzzle we did time-resolved PL experiments on single QDs in a high density sample. We present time-resolved PL of single QDs in a high density sample. The carrier capture and relaxation time is found to depend strongly on the QDs density and the generated carrier density.