Highly carbon‐doped Ga0.47In0.53As layers grown by chemical beam epitaxy have been exposed to a deuterium plasma. Deuterium diffusion profiles reflect very strong C–D interactions. Concerning electronic transport properties, fromp‐type when as‐grown, these GaInAs samples turn ton‐type after plasma exposure. Annealings of deuterated layers have also been performed. They show that temperatures as high as 450 °C must be reached beforep‐type conductivity is fully restored in the material. ©1996 American Institute of Physics.