Influence of the thermal treatment on the optical and structural properties of 1.3 μm emitting LP-MOVPE grown InAs/GaAs quantum dots

The optical and structural properties of a single array of 1.3 μm emitting quantum dots (QDs) grown by LP-MOVPE are presented after different thermal treatments (between 570°C and 670°C under arsine flux during 25 min) simulating the overgrowth of the confinement layers for broad area lasers. The photoluminescence (PL) efficiency of the 1.3 μm line is not affected by a thermal treatment below 620°C. Nevertheless, a drastic decrease of the 1.3 μm peak intensity occurs for higher anneal temperature (670°C), together with an important blueshift of the PL spectrum (≈40 meV). The structural modifications of the QDs were studied by TEM, showing an important In/Ga intermixing during the thermal treatment. A low thermal budget (<620°C) during the growth is clearly required to avoid the PL spectrum blueshift.