Type-II excitons in ZnTe/ZnSe quantum dots

We present the photoluminescence and time resolved photoluminescence properties of an ensemble of ZnTe quantum dots embedded in a ZnSe matrix. Those heterostructures exhibit a type-II band alignment with holes confined within the dots and electrons kept in the close vicinity of the dots by coulomb attraction. We show that the structural and optical features of the samples, grown by molecular beam epitaxy, are highly sensitive to the growth conditions. Depending on the Se to Zn flux ratio, the ZnTe islands can disappear and lead to a thin 2D quantum well, or be preserved and localize excitons, as evidenced by photoluminescence experiments. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)