Emission dynamics of InAs self-assembled quantum dots with different cap layer structures

The emission dynamics properties of self-assembled InAs quantum dots with different cap layers are investigated by steady-state and time-resolved photoluminescence (PL). The uniformity of the dots can be improved by the proper cap layer structure. It is found that the InGaAs and InAlAs combination cap layer structure could more effectively release the strain in QDs, suppress the indium segregation, enhance the confinement effect on carriers and reduce the thermally induced carrier escape from QDs. This has led to QDs with narrower emission, above 1.3 mu m, and to improved temperature stability of PL intensity and has resulted in an increase of the PL decay time to 10 ns at 160 K.