Optical anisotropy in self-assembled InP quantum dots

Strong optical anisotropy is observed in the photoluminescence (PL) bands o f both the InP self-assembled quantum dots and the Ga0.5In0.5P matrix. From the linearly polarized PL spectra measured under weak excitation, we found that large size quantum dots show strong anisotropy. The luminescence from a single quantum dot observed by the micro-FL technique revealed a doublet fine structure of the exciton levels that obey the linear polarization sel ection rule. The observed fine structure is shown to arise from an interpla y of the electron-hole exchange interaction and the asymmetric crystal stru cture of the InP/Ga0.5In0.5P system.