InAsxP1−x has been implanted with sulphur and silicon with the view of forming low-resistivity n-type layers. Resulting activity from 1015 cm−2 implants indicate SiO2 to be an adequate encapsulant at the required 700–750°C annealing. Sheet resistivities down to 2.5 to 3, 4 and 8Ω/□, respectively, are obtained for the three compositions InAs0.75P0.25, InAs0.5P0.5 and InAs0.2P0.8 investigated.