We report a study of electrophotoluminescence in a biased shallowGaAs/AlxGa1−xAs(x=0.04)quantum well. It is shown that photocarriers escape from the well via direct tunneling, resulting in a drastic quenching of the photoluminescence at remarkably low fields(F<10 kV/cm).We develop a simple method to measure the field-induced escape time from a set of cw photoluminescence, photocurrent, and time-resolved photoluminescence experiments. Comparison with a semiclassical model shows that, in this regime, Coulomb interaction affects significantly the single electron direct tunneling scheme. ©1998 American Institute of Physics.