Convex-shaped decay curve of carriers in a vertically coupled InAs/GaAs quantum dot

Abstract

In a study using time-resolved photoluminescence (PL) to examine the carrier dynamics of a vertically coupled InAsGaAs quantum dot (QD) of 20 periods, we observed an initial slow carrier decay followed by a fast decay. The time at which the transition from slow to fast decay occurred increased on going to lower QD states at a fixed excitation power, and increased with increasing excitation intensity at a fixed QD state. This behavior is attributed to the relatively efficient vertical transfer of carriers in the vertically coupled InAsGaAs QD. In addition, this vertical carrier transfer makes the rise of the PL signal slower at lower-energy states. This peculiar carrier dynamics behavior was not observed in a single-layered QD or in a vertically uncoupled QD of 20 periods. © 2005 American Institute of Physics.