InxGa1−xAsyP1−yepilayers lattice matched to InP were grown from the liquid phase at temperatures far above the commonly used temperature range. The goal was to get off the unstable region corresponding to compositions emitting in the wavelength range of 1.2 &mgr;m<&lgr;<1.5 &mgr;m at 650 °C. In0.71Ga0.29As0.65P0.35(&lgr;=1.35 &mgr;m) layers thus grown have the highest electron Hall mobilities ever obtained in this material: &mgr;300 K=7000 cm2/Vs and &mgr;77 K=23 200 cm2/Vs forND−NA=8.1014cm−3. We suggest that a contribution to mobility limitation might be related to the composition modulations present in epilayers grown in the usual temperature range.