Properties of photoluminescence in type-II ZnTe/ZnSe quantum dots

Abstract

Temperature and time evolution of the photoluminescence (PL) intensity of bimodal ZnTe/ZnSe type-II quantum dots (QDs) were investigated. A particular temperature dependence of PL was observed in large QDs. PL decay of small QDs is composed of a faster initial component and a slower tail component whereas PL decay of large QDs simply comprises a fast component. All phenomena could be understood consistently by considering charge carrier transfer mechanism, band-bending effect, and the existence of nonradiative centers in the bimodal type-II QD array. We show that excitons play an important role in the emission properties of a self-assembled type-II QD system.