Self-assembled InAs quantum dots with two different matrix materials

The effects of matrix materials on the structural and optical properties of self-assembled InAs quantum dots (QDs) grown by a molecular beam epitaxy were investigated by atomic force microscopy, cross-sectional transmission electron microscopy (TEM), and photoluminescence (PL) spectroscopy. Cross-sectional TEM image indicated that the average lateral size and height of InAs QDs in a GaAs matrix on a GaAs substrate were 20.5 and 5.0 nm, respectively, which showed the PL peak position of 1.19 μm at room temperature. The average lateral size and height of InAs QDs buried in an InAlGaAs matrix on InP were 26.5 and 3.0 nm, respectively. The PL peak position for InP-based InAs QDs was around 1.55 μm at room temperature. If we only consider the size quantization effects, the difference in PL peak position between two QD systems with different matrices may be too large. The large difference in peak position can be mainly related to the QD size as well as the strain between the QDs and the matrix materials. The intermixing between the QDs and the matrix materials can partially change the In composition of QDs, resulting in the modification of the optical properties.