Activation energy and carriers dynamics of multilayer CdTe/ZnTe quantum dots with different ZnTe separation layer thicknesses

Abstract

We studied the optical properties of multilayer CdTe/ZnTe quantum dots (QDs) with various ZnTe separation layer thicknesses on GaAs substrates. The low temperature photoluminescence (PL) spectra show that the excitonic peaks in multilayer CdTe/ZnTe QDs shift to higher energy levels, and PL peak intensities increase with increasing ZnTe separation layer thickness. This is because of increasing uncoupling and because there are many more carriers confined in the QDs with wider separation layers. Temperature-dependent PL measurements showed that the activation energies of the confined electrons in the multilayer CdTe/ZnTe QDs decreases with decreasing ZnTe separation layer thickness. The time resolved PL spectra show increasing carrier decay times with decreasing ZnTe separation layer thickness, due to increasing coupling between QDs with narrower separation layers. (C) 2017 Elsevier Ltd. All rights reserved.