Electrical activation and dopant diffusion in Zn-implanted InP after rapid thermal annealing have been investigated. For an as-implanted Zn concentration of∼4×1019 cm−3,only ∼7&percent; of the implanted Zn atoms formed electrically active shallow acceptors following a 950 °C/5 s annealing cycle. The low activation was the result of rapid Zn out-diffusion—only ∼14&percent; of the implanted dopant was retained after annealing. A significant enhancement in electrical activation and a reduction in Zn loss were achieved inZn+Pco-implanted samples which yielded a net hole concentration of⩽6×1018 cm−3and >50&percent; Zn retention. The saturation of the free hole concentration inZn+Pco-implanted samples was attributed to the formation of Zn interstitial donors and Group-V-related donor-type native defects. For comparison,Zn+AlandZn+Al+Pco-implanted samples were also examined to distinguish the relative influences of implantation-induced disorder and nonstoichiometry on electrical activation and dopant diffusion. For the given implant conditions, we found that nonstoichiometry was the dominant influence. ©1998 American Institute of Physics.