Thin epitaxial layers (< 1.5 μm) of Ga0.47In0.53As were grown by molecular beam epitaxy, very closely lattice-matched to InP, despite a nonrotating substrate holder. Hall mobilities were measured as a function of temperature in the dark and on illumination. At low temperature, the peak mobility of undoped layers lies between 35000 and 40000 cm2V−1s−1 in the dark and increases up to 45000 cm2V−1s−1 when measured in the light. Preliminary results obtained on slightly Sn-doped layers are also reported.