InGaAs/GaAs quantum-dot–quantum-well heterostructure formed by submonolayer deposition

The fabrication, characterization, and exploitation of self-assembled quantum dot heterostructures have attracted much attention not only in basic research, but also due to the promising device applications such as in QD lasers. Discrete emission lines from self-assembled InGaAs quantum dots (QDs) grown in the submonolayer (SML) deposition mode have been observed in micro-photoluminescence (PL) spectra at 10 K. For the first time, the SML-grown InGaAs/GaAs QD heterostructure is verified to be a quantum-dot-quantum-well (QDQW) structure, by using high power PL and selective PL with excitation energies below the band gap of the GaAs barriers and temperature dependent PL. As the temperature is increased from 10 to 300 K, a narrowing of the full width at half-maximum at intermediate temperatures and a sigmoidal behaviour of the peak energy of PL band of the SML QD ensemble are observed and attributed to thermally activated carrier transfer between QDs via QW states.