Time-resolved and temperature-dependent photoluminescence studies on CdTe/ZnTe quantum dots with different ZnTe capping layer thicknesses

We investigate the effects of the capping layer thickness on the optical properties of CdTe/ZnTe quantum dots (QDs). The time-resolved photoluminescence (PL) measurements used to study the carrier dynamics show a shorter decay time for CdTe/ZnTe QDs with decreasing thickness of the ZnTe cap layer due to an increase in the nonradiative surface recombination rate. The activation energy of the electrons confined in the CdTe/ZnTe QDs, as obtained from the temperature-dependent PL spectra, decreases with the thickness of the ZnTe cap layer. These results indicate that the carrier dynamics and activation energy of CdTe/ZnTe QDs are affected by the thickness of the ZnTe cap layer.

► Optical properties of CdTe/ZnTe quantum dots (QDs) are investigated. ► Different ZnTe capping layer thicknesses are used for the QDs. ► QD photoluminescence peak shifts to a higher energy with cap layer thickness increase. ► Decay time of QDs decreases with cap layer thickness decrease. ► Activation energy of QDs increases with cap layer thickness increase.