Determination of the minimum island size for full exciton localization due to thickness fluctuations in Zn1−xCdxSe quantum wells

Fluctuations of the thickness of quantum wells (QWs) of few monolayers are one of the causes of exciton localization. Here, we present the results of the determination of the minimum lateral dimensions of islands produced by thickness fluctuations in Zn_1−xCd_xSe QWs, which cause full exciton localization. We have calculated the localization energy of excitons in the frame of the factorized-envelope approximation. We found that the excitons are well localized in the islands of the QW when their lateral dimensions are larger than ∼15 times the exciton Bohr radius.