Dual implantations of 150 keV Si+ions and 160 keV P+ions with the same dose of 1×1015/ cm2were performed at 200 °C. Si3N4encapsulated samples were annealed in a conventional furnace or a halogen tungsten lamp rapid thermal annealing system. The carrier concentration profiles show that the Si dopant is highly activated and its indiffusion is effectively reduced with the help of P+implantation and rapid thermal annealing. The highest carrier concentration of 5×1019/cm3, corresponding to an activation of 70%, an average electron mobility of 750 cm2/V s, and a sheet resistance of 11 &OHgr;/&laplac;, has been obtained in Si+and P+dually implanted InP after rapid thermal annealing at 850 °C for 5 s.