Optical properties of epitaxial InAs/GaAs quantum dots overgrown under different V/III flux ratios

We study the optical properties of InAs/GaAs(001) quantum dots (QDs) overgrown under different V/III flux ratios using photoluminescence (PL) and excitation spectroscopy. When the V/III flux ratio is low, a series of pronounced QD-related peaks is observed in the $77-\mathrm{K}$ PL spectrum over a $200-\mathrm{meV}$ broad spectral interval with the brightest one located at 1.37 eV. With increasing V/III flux ratio, the PL spectrum is red-shifted (to 1.16 eV) and then blue-shifted again (to 1.26 eV), while becoming smoother. We explain this behavior in terms of enhanced QD decomposition, the mechanism of which is different in cases of deficiency and excess of arsenic during the overgrowth.