A new approach for capless rapid thermal annealing of ion implanted III‐V semiconductors, the enhanced overpressure proximity (EOP) technique, has been developed and applied to GaAs implanted with Si+. The EOP method relies on the use of a Sn‐coated GaAs wafer to provide a localized arsenic overpressure around the ion implanted wafer during the annealing cycle. The arsenic overpressure resulting from this arrangement is greater than the overpressure obtained with the conventional proximity method, which utilizes an untreated GaAs wafer as an arsenic source. This new annealing technique has yielded higher electrical activation and electron mobilities in GaAs than the conventional proximity method as well as an increased latitude in annealing times and temperatures. The EOP approach can be easily extended for capless rapid thermal annealing of other III‐V compounds such as InP and InGaAs.