Journal of Crystal Growth, Vol.214, 660-664, 2000
Exciton localization in cubic CdS/ZnSe type-II quantum-well structures
We investigate the exciton localization in cubic CdS/ZnSe type-II superlattices using spatially integrated and spatially resolved photoluminescence spectroscopy. Spatially resolved photoluminescence images (intensity landscapes) show local reductions of the emission intensity. This can be attributed to potential profiles arising from fluctuations in layer thicknesses. Furthermore, narrow line emission (FWHM approximate to 300 mu eV) superimposed on a broad photoluminescence background (FWHM around 30 meV) is observed. Temperature-dependendent investigations reveal the contributions of the usual band-gap shift and phonon-assisted hopping processes to the non-monotonous shift of the spatially integrated luminescence maximum. When comparing the behaviour of the superlattices with the photoluminescence properties of single quantum wells we observe strong differences.