The electrical characteristics ofp+‐njunctions in undoped InP fabricated by using a deep Si implant and a shallow Be implant are reported. It proved advantageous to anneal the two implants separately. The influence of annealing, implantation temperature, and Si dose on leakage current is studied systematically. It is found that prolonged anneals and elevated temperatures reduce leakage currents and that raising the implantation dose increases junction leakage considerably. It is shown that junction behavior can be modeled by assuming a trap‐assisted tunneling mechanism. In this model the magnitude of the electric field at the junction is the most decisive parameter. For a 15‐min‐long anneal at 850 °C leakage current densities <10−7A/cm2are obtained for an electric field of 40 V/&mgr;m at the junction.