AlAs monolayer dependence of the radiative recombination rate in a type II GaAs–AlAs double quantum well

In a GaAs/AlAs/GaAs type II double quantum well with thickness gradient we study the ratio of photoluminescence intensities of the zero-phonon line and the phonon replica as a function of AlAs thickness. From the time-resolved photoluminescence we determine the radiative times due to the Γ–X coupling and to the phonon-assisted transition. Both time integrated and time-resolved results show clear evidence of the monolayer dependence of the Γ–X coupling matrix element on AlAs thickness.