Competition between confinement potential fluctuations and band-gap renormalization effects inIn0.53Ga0.47As/In0.525Ga0.235Al0.25Assingle and double quantum wells

We present the results of our studies on the emission properties of ${\text{In}}_{0.53}{\text{Ga}}_{0.47}\text{As}/{\text{In}}_{0.525}{\text{Ga}}_{0.235}{\text{Al}}_{0.25}\text{As}$ single and coupled double quantum wells (CDQWs) with different degrees of potential fluctuation. We have verified that the curve of the temperature $(T)$ dependence of the emission peak energy $({E}_{\text{PL}})$ is significantly influenced by the potential fluctuations (which are magnified by the presence of the internal barrier in the CDQW) as well as by the excitation density used in the photoluminescence (PL) measurements. As the excitation power increases, two effects occur simultaneously: the filling of the band-tail states related to potential fluctuations and the band-gap renormalization (BGR) caused by the increase in the density of photogenerated carriers. As the optical density increases, the ${E}_{\text{PL}}$ can shift to either higher (blueshift) or lower (redshift) energies, depending on the temperature at which the measurements are carried out. The temperature at which the displacement changes from a blueshift to a redshift is governed by the magnitude of the potential fluctuations and by the variation of BGR with excitation density.