Self-organized InAs quantum dots (QDs) on InP (1 0 0) substrate have been prepared by solid-source molecular-beam epitaxy (SSMBE). Atomic force microscopy (AFM) examination shows that the InAs QDs possess low aspect ratio(1 : 17) of height vs. diameter. The low-temperature photoluminescence (PL) behavior of the QDs is characterized by a 65 meV PL linewidth at - 0.8 eV, with three other emissions, which correspond to the various thicknesses of InAs wetting layers. It is deduced that the InAs wetting layers exceeded the intended InAs deposition, which is attributed to unintentional As/P exchange reaction. This excess material is further confirmed by XRD measurements, and indicates that effective exchange occurs even at low temperature (500 degrees C) for SSMBE growth. No significant change in the QD emission peak is observed in the sample grown at high temperature, indicating the absence of any significant As/P exchange reaction in the QDs.