The capture and emission dynamics of deep levels inGaAs/Ga1−xAlxAsmultiple quantum well structures are investigated by using the photoinduced transient spectroscopy technique. In nominally undoped samples three trapping levels with activation energies in the range between 0.4 and 0.8 eV are observed. These are compared with the observations based on other conventional techniques. Large capture cross sections associated with the trapping centers implies that the presence of these can be detrimental for the high speed operation of optoelectronic devices based onGaAs/Ga1−xAlxAsquantum well structures. ©1997 American Institute of Physics.