Photoluminescence investigation of InAs quantum dots in quantum well with different strain reducing layer

The emission dynamics properties of InAs self-assembled quantum dots (QDs) embedded in InGaAs/GaAs quantum well with different strain reducing layer (thin InAlAs and GaAs) were systematically investigated by time-resolved and temperature dependent photoluminescence (TR and TD PL) measurements. We observe that a thin 10 monolayer (ML) GaAs layer may increase the emission wavelength, and 1 nm additional InAlAs layer results a significant nonlinear red-shift of above 1.3 mu m photoluminescence (PL) peak, which can be explained from the strain analysis. TDPL spectra display an anomalous enhancement behavior of the integrated PL intensity around 150 K for the InAs QD structures without the InAlAs layer, which may be described by the reduced carrier transition at higher temperature for the higher energy barrier of the InAlAs layer. We study systematically PL decay time of the InAs with different structures. The PL lifetime of quantum dots grown on a 10 ML GaAs layer is a littler longer than those without the layer, and a more InAlAs layer may result in a greatly increase of PL lifetime, which implies that the InAlAs layer with higher energy barrier may enhance the quantum restriction of carriers in InAs QDs. The above phenomena also approve the facts that the main mode of carrier migration is quantum tunneling effects at lower temperature, while it is the quantum transition at the higher temperature. We explained these measuring results from the competition between the carrier recombination, escape and redistribution.