Abstract: Based on the equation of the current continuity, the analytical expression of carrier and current densities is presented. In the calculation, the boundary condition is determined by considering the injection current that can be easily measured in experiments. We discussed the distributions of electron density and electron current density, analyzed the influence of electric field on the electron density, electron current density and recombination efficeiency, and investigated the effect of the electric field and potential barrier on recombination efficiency. The theoretical values based on the model are basically in agreement with the results that have been reported in the literature.