Shape-mediated anisotropic strain in self-assembled InP/In_0.48Ga_0.52P quantum dots

InP quantum dots grown on (001) InGaP/GaAs exhibit a pronounced size anisotropy with respect to the [110] and [11¯0] directions. This asymmetry leads to a remarkable polarization dependence of photoluminescence spectra and to different elastic relaxation in these directions. The strain distribution is investigated by x-ray diffuse scattering along with respective kinematical simulations using linear elasticity theory. The geometric aspect ratios of island height and island base widths are evaluated with high accuracy and the influence of these ratios on the strain field inside the quantum dots is discussed.