Polarization anisotropy of exciton in self-assembled elliptical InP/InGaP quantum dots

• Effective size anisotropy is addressed from the polarization dependence of elliptical InP quantum dots.
• The same polarization anisotropy is observed despite the large size inhomogeneity.
• The oscillator strength is enhanced by the dipole-dipole interaction between nearest quantum dots.

Optical anisotropy of self-assembled elliptical InP quantum dots has been investigated in terms of the polarization dependence of excitons. Although large size inhomogeneity is present, two kinds of characteristic quantum dots, which are classified into large and small quantum dots, were found in terms of the polarization anisotropy. We have confirmed that the large quantum dots are more pronounced in the polarization anisotropy, where the degree of linear polarization for the large quantum dots is significantly larger (∼60%) than that for the small ones (∼36%). The effective shape of quantum dots is also estimated by using the size dependence of oscillator strength, which is in agreement with the AFM image. We also suggest that the anisotropy of exciton oscillator strength can be modified via the dipole–dipole interaction between nearest exciton dipoles.