Photoluminescence (PL) of Te-doped In0.5Ga0.5P epilayers grown by the liquid phase epitaxy technique has been investigated as a function of carrier concentration. The PL results are interpreted using a model taking into account nonparabolicity of the conduction band. Both the band filling as well as band tailing due to the Coulomb interaction of free carriers with ionized impurities and band shrinkage due to the exchange interaction between free carriers are considered in order to properly portray the observed features of the PL spectra. The theoretical calculations are in satisfactory agreement with the observed PL results. The PL line shape is well explained by a direct transition with a simplek-selection rule up to a carrier concentration of 2.0×1018cm−3. Above the carrier concentration of 2.0×1018cm−3, on the other hand, it is properly interpreted in terms of non-k-conserving transitions that arise from the indirect recombination of electrons in a highly filled conduction band. It was found that a concentration dependent gap shrinkage due to the exchange interaction in Te-doped In0.5Ga0.5P at 17 K is described by the relationEce=2.34×10−8n1/3(eV). The concentration dependent effective mass has also been calculated using Kane’s three band model. ©1997 American Institute of Physics.