Ohmic contacts are optimized on δ-doped lattice-matched (x=0.53) and pseudomorphic (x=0.80) lno.53Gao.47As/Alo.52Ino.48As/InxGa1-xAs/AI0.52ln0.48As layers grown on InP by molecular beam epitaxy (MBE). The layers are characterized by temperature-dependent Hall measurements (4-300 K) and Shubnikov-de Haas measurements at 1.2 K. Lowest specific transfer resistance (< 0.1 O.mm) is obtained with a Ni/AuGe/Ni/Au metal sequence alloyed at 280 °C for 1 min. The influence of the Ni content in the metallization is studied and AuGe layers evaporated from the eutectic composition (Au:Ge, 88:12 weight %) are compared with successively evaporated Au and Ge layers. It is shown that the resulting contact resistance is not very sensitive to changes in these parameters. The solid state reactions involved are studied by sputter Auger depth profiling.