Radiative decay in type-II GaP/AlP/GaP quantum wells

We have studied time-resolved photoluminescence (PL) of type-II GaP/AlP/GaP quantum wells with different well widths and acquired detailed information concerning the mechanisms of the radiative recombination. At low temperatures, the PL spectra consist mainly of a no-phonon line. The decay of the no-phonon line was slow and nonexponential. The decay curves could be fitted to a model which assumes that the radiative recombination occurs as the result of both incoherent and coherent Γ-X scattering due to disorder at the interface. The fit revealed that the dominant Γ-X mixing mechanism was random scattering caused by fluctuations in the potential at the interface. Based on simple perturbation theory, the observed increase in the radiative decay rate with decreasing well width was explained by the increase of overlap of the electron envelope wave functions as well as the decrease of Γ-X energy separation. The model suggests that the magnitude of the potential responsible for the Γ-X mixing is considerably greater than those observed in the type II GaAs AlAs heterostructures.