Thermal escape of carriers out of CdTe/ZnMgTe nanostructures

We report on time-resolved photoluminescence (PL) measurements up to room temperature of CdTe/Zn1−xMgxTe narrow quantum wells (QWs) and quantum dots (QDs). Whereas the low-temperature dependence of the PL decay time τ is characteristic of systemʹs dimensionality, the Arrhenius plot of its high-temperature dependence directly gives the thermal activation energy of the loss channel limiting the emission in these nanostructures. By varying the Mg-content of the barriers, we unambiguously identified the unipolar escape of the less confined carriers, namely heavy holes, to be the main non-radiative mechanism. With increasing Mg-barrier composition, both CdTe QWs and QDs show a radiative regime extended to higher temperatures together with a non-radiative regime exhibiting a higher activation energy.