Sulfur‐ (ntype) and magnesium‐ (ptype) doped InGaP layers grown by liquid‐phase epitaxy are investigated by low‐temperature photoluminescence (PL) measurements in the energy range between 1.55 and 2.25 eV (800–550 nm). The PL spectrum of nominally undoped InGaP epilayer shows four different peaks. Besides a bound exciton recombination peak, three longitudinal optical‐phonon replicas with one superimposed donor–acceptor emission are identified based upon their dependence of emission energies on temperature and excitation intensity. For heavily sulfur‐doped epilayers, the transition peak from the conduction‐band filling level shifts toward higher energy with increasing electron concentration. However, the near‐band‐edge emission peak shifts toward lower energy with increasing hole concentration due to band‐gap shrinkage in magnesium‐doped epilayers. A near‐band‐edge radiative emission mechanism is also proposed to explain the observed phenomena. ©1996 American Institute of Physics.