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

GaInP lattice matched to GaAs (001) and InP/GaInP self-assembled quantum do ts were grown by gas-source molecular beam epitaxy. Transmission electron m icroscopy and photoluminescence reveal that the composition-modulated later al superlattice along the [110] direction dominates over Cu-Pt-B type long- range ordering on determining the strong spectral polarization of GaInP alo ng the [<1(1)over bar>0] direction. InP dots embedded in GaInP with the lat eral superlattice show the same polarization in the photoluminescence spect ra, the degree of polarization of quantum dots increases with that of the s urrounding 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 c omposition modulation in the GaInP matrix is considered to be the major ori gin for the strong optical anisotropy in the InP/GaInP quantum dot system.