Lateral composition modulation induced optical anisotropy in InP/GaInP quantum dot system

GaInP lattice matched to GaAs (001) and InP/GaInP self-assembled quantum dots were grown by gas-source molecular beam epitaxy. Transmission electron microscopy and photoluminescence reveal that the composition-modulated lateral superlattice along the [110] direction dominates over Cu-Pt-B type long-range ordering on determining the strong spectral polarization of GaInP along the [<1(1)over bar>0] direction. InP dots embedded in GaInP with the lateral superlattice show the same polarization in the photoluminescence spectra, the degree of polarization of quantum dots increases with that of the surrounding GaInP matrix to as high as 40%. Although the shape elongation of InP dots along the [<1(1)over bar>0] direction is also observed, lateral composition modulation in the GaInP matrix is considered to be the major origin for the strong optical anisotropy in the InP/GaInP quantum dot system.