Optical anisotropy of excitons and biexcitons in InP quantum dots

A single-quantum dot spectroscopy enabled us to observe exciton, biexciton and triexciton in the s-shell, p-shell and d-shell structures in InP quantum dots. Polarized luminescence spectroscopy of the single-quantum dots showed optical anisotropy of excitons and biexcitons. Exciton and biexciton luminescence are co-linearly polarized but polarization is oriented towards different directions dot by dot depending on the local order of the surrounding In0.5Ga0.5P matrix. Anisotropic exchange energy splitting was seen in the polarized luminescence of single-quantum dots.