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

The optical and structural properties of a single array of 1.3 mum emitting quantum dots (QDs) grown by LP-MOVPE are presented after different thermal treatments (between 570 degreesC and 670 degreesC 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 mum line is not a ffected by a thermal treatment below 620 degreesC. Nevertheless, a drastic decrease of the 1.3 mum peak intensity occurs for higher anneal temperature (670 degreesC), together with an important blueshift of the PL spectrum (a pproximate to 40 meV). The structural modifications of the QDs were studied by TEM, showing an important In/Ga intermixing during the thermal treatmen t. A low thermal budget (< 620 degreesC) during the growth is clearly requi red to avoid the PL spectrum blueshift. (C) 2001 Elsevier Science B.V. All rights reserved.