Si (100) wafers were implanted at 500 °C with 250 keV As ions and 350 keV In ions in this order. The implantations were carried out with three different fluences, namely 1 × 1016, 2 × 1016, and 5 × 1016 cm−2. The samples were annealed with rapid thermal annealing (RTA) for 30 s at temperatures ranging from 800 up to 1000 °C. Different techniques like photoluminescence (PL) and Rutherford backscattering spectrometry (RBS) were employed to characterize the samples. Finally, scanning and transmission electron microscopy (SEM and TEM, respectively) provided further structural information of the InAs nanoclusters. The results indicate that InAs nanoprecipitates are formed after RTA treatment. Moreover, a broad photoluminescence peak was observed in all samples submitted to RTA. RBS results reveal that losses of implanted ions due to diffusion processes can be minimized through the use of RTA, depending of the fluence of ion implantation. Finally, the present results suggest that the photoluminescence yield depends on the degree of the radiation damage induced in the Si matrix during the implantation process.