Retrapping of carrier emission in photoluminescence decay time in InAlAs quantum dots with different thickness

The effect of thickness have been investigated on the optical properties of InAlAs/GaAlAs quantum dots (QDs). The photoluminescence (PL) and time-resolved photoluminescence (TRPL) have been studied on temperature dependences. A sudden decrease in the PL energy emission with increasing InAlAs thickness indicates that the optical emission comes from the wetting layer to QDs, while the full width at half maximum (FWHM) abruptly increases due to the efficient relaxation process. The density of InAlAs QDs decreases as the InAlAs thickness increases from 4.2 to 6.4 monolayers (ML). With increasing excitation power, the QD emission energy was red-shifted for the highest ML, attributed to the carrier trapping. A strong decrease in the exciton lifetime with increasing ML has been observed on temperature dependence induced by the QD zero-dimensional confinement.