Photoluminescence and Raman spectroscopies are employed to study undoped InGaP layers grown on GaAs (100) substrates at 750 °C by liquid phase epitaxy. There are four peaks in the photoluminescence spectrum in the energy range between 1.55 and 2.25 eV. Besides a bound exciton recombination, three longitudinal optical phonon replicas with one superimposed donor‐acceptor emission are identified based upon their dependences of emission energies on temperature and excitation intensity. ©1995 American Institute of Physics.