In this paper, carrier kinetics in a type II multiple quantum well hetero-n-doped-intrinsic–p-doped-intrinsic are studied through optical measurements under continuous illumination. Both field measurement by photoreflectance and time measurement confirmed our hypothesis that the recombination time is a function not only of photocarrier density, but also of photocarrier distribution. A simple model is used for recombination time, assuming exponential dependence on the barrier height and nearest distance between recombining carriers. Quantum efficiency has also been determined. ©1997 American Institute of Physics.