Rapid thermal annealing (RTA) of Sn‐implanted InP has been investigated with a variety of analytical techniques including electrical measurements, Rutherford backscattering spectrometry, transmission electron microscopy and secondary‐ion‐mass spectrometry. RTA is shown to yield high electrical activation with negligible dopant diffusion. Incomplete electrical activation can result from dopant/defect complexes, native defect compensation, nonstoichiometry and dopant precipitation where the relative contribution of a given factor is dependent on both ion dose and annealing temperature. P coimplantation is shown to increase electrical activation through an increase in the number of ionized donors via a decrease in the number of dopant/defect complexes (in contrast to lattice site switching characteristic of dopant amphoteric character). ©1995 American Institute of Physics.