The radiative recombination processes in CuGaS2, deposited in vacuum by the co-evaporation of elemental sources, are investigated in order to understand the intrinsic defect levels in Cu-rich material. Steady state photoluminescence (PL) spectra at different excitation densities and the time-delayed PL response are studied in order to extract the nature of the radiative transitions in the material. It is shown that the 2 K PL response of Cu-rich layers is dominated by two donor-acceptor pair transitions. The three defect levels involved have ionization energies of similar to53, similar to210 and similar to250 meV (C) 2003 Elsevier Science B.V. All rights reserved.