We report the solid source molecular beam epitaxial growth of InAs/InP quantum dot (QD) superlattices and the effect of As/P exchange on the interface between InAs and InP. The InAs QDs were found to have an average lateral diameter of ∼40 nm and a density of 3–4×109 cm−2. The QDs superlattice has photoluminescence (PL) emission centred at 0.77 eV with a linewidth of 64 meV at low temperature (4 K). X-ray diffraction (XRD) spectra showed evidence of significant As/P exchange on the interface between InAs and InP during in situ annealing under P2 pressure before growing the spacer layer of InP. An average P composition of ∼30% in the resulting InAsP QDs in samples annealed for 50 s was deduced from dynamical simulations of the experimental XRD spectra. The QDs superlattice PL emission exhibits a blueshift following an increase in annealing time, and emission at 1.55 μm and at 300 K was achieved. This observation holds promise for possible telecommunication device applications at long wavelengths.