Optical properties of the InAs/InAlGaAs quantum dots subjected to thermal treatments

The inter-diffusion kinetics of group-III elements at the interface between self-assembled InAs quantum dots (QDs) and InAlGaAs barriers were investigated indirectly by post-growth annealing treatments and photoluminescence (PL) spectroscopy. The emission wavelength of the InAs/InAlGaAs QDs subjected to thermal annealing at 550 °C was 1444 nm at 10 K, which indicated a 57 nm red shift compared to the as-grown sample (1387 nm). The emission wavelength was blue-shifted with further increases in annealing temperature to 650 °C. Although there was a blue shift in the emission wavelength at an annealing temperature of 600 and 650 °C, the emission peak was still longer than that of the as-grown sample. These results were explained by the difference in inter-diffusion probability between group-III elements at the interface between the InAs QDs and InAlGaAs barrier.