A comparison of ion irradiation-induced intermixing in GaAs-Al0.54Gao46As quantum well structures with H, O and As ions is investigated by low temperature photoluminescence. Very large energy shifts are observed together with good recovery of the photoluminescence intensities after annealing in samples irradiated with protons. No saturation in the energy shifts is observed in samples irradiated even up to a dose of 4.3 x 1016 cm-2. Similar large shifts with low absorption are also observed in O and As implanted samples but at a significantly lower ion dose. However, both the heavier ions show a saturation effect in the degree of intermixng at higher doses. The degree of intermixing is believed to be a delicate balance among multiple competing processes that occurs across the interface.