Photoluminescence decays fromn‐GaAs/Na2S contacts following picosecond pulse excitation are presented. Decays measured at several different potentials from depletion to accumulation regimes all exhibit a strong dependence on excitation power when the photon flux is greater than 1010photons/cm2/pulse. Using a flux of 4×1012photons/cm2we model the potential dependence of the decays by adjusting only the value of the surface minority trapping velocity. These results are used to evaluate the applicability of the modified dead layer model in the analysis of photoluminescence intensity versus potential measurements as a means of measuring surface minority trapping velocities in photoelectrochemical cells.