Optical anisotropy and photoluminescence excitation density dependence for auto-organized Al0.28In0.72As/Al0.28Ga0.72As quantum dots

In this paper, we present a study of photoluminescence (PL) from Al0.28In0.72As/Al0.28Ga0.72As quantum dot (QD) structures grown by molecular beam epitaxy. We have found that the surface-emitted PL is linearly polarized with a polarization degree of 0.2. The study of the excitation-density-dependent PL spectra reveals an unusual behaviour of the full-width at half-maximum (FWHM), which increases, then decreases with increasing excitation density. On the other hand, the decay time decreases from 630 to 430 ps when the excitation density is varied from 140 to 5600 W cm−2.