In this work the incorporation of oxygen in Al0.2Ga0.3In0.5P:Be layers lattice-matched to GaAs grown by solid source molecular beam epitaxy (SSMBE) was studied by secondary ion mass spectrometry (SIMS) and photoluminescence (PL) spectroscopy. By increasing the temperature of the phosphorous cracking zone from 800 to 1000 degrees C the amount of oxygen was considerably raised by more than one order of magnitude as measured by SIMS. The increasing oxygen content resulted in the creation of radiative deep-defects in the samples, some of them identified as transitions between O-related moderately deep donor-like states and Be-acceptor levels (D(d)AP) as observed by low-ternperature PL spectroscopy. other observed lines were associated with Be-acceptor levels (A(0),X), shallow impurities (A,X) and the band-to-band transition (B,B). On the other hand, as the beryllium concentration increased the PL intensity of the A(0),X and DdAP lines increased, indicating that Be-incorporation it) the Al0.2Ga0.3In0.5P epilayers enhances the probability that A(0),X and D(d)AP transitions occur. After annealing the samples, the D(d)AP transition significantly increased due to further activation of O-related moderately deep donor-like states. Also the 15 K-PL spectra from annealed samples showed another lower-energy broad band located at 0.271 eV below the AlGaInP band edge, presumably related with oxygen deep-defect levels (O,DL). (C) 2008 Elsevier B.V. All rights reserved.