Temporal cross-section for carrier capture by self-assembled quantum dots

Time-resolved studies of the wetting layer photoluminescence is combined wi th state-filling spectroscopy of the quantum dot emission to obtain carrier transfer rates from the wetting layer to the quantum dot states. This meth od allows us to obtain the capture rates as a function of wetting layer car rier concentration, a result that cannot be obtained from a time-dependent measurement of the quantum dot emission itself. The results show unambiguou sly that the capture efficiency increases significantly with the carrier co ncentration in the wetting layer, indicating the dominant role of Auger pro cesses in the capture dynamics. In the analysis the concept of capture cros s section per unit time is introduced to take into account possible changes in capture times for different dot areal densities.