Enhancement of the activation energy due to coupling effects in Cd _xZn_1-xTe/ZnTe double quantum dots

Temperature-dependent photoluminescence measurements show that the activation energy of Cd0.6 Zn0.4 TeZnTe double quantum dots (QDs) increases with decreasing ZnTe separation layer. At a separation-layer thickness of 6 nm, this behavior can be attributed to enhancement in the tunneling probability of carriers from the smaller Cd0.6 Zn0.4 Te 1.5-monolayer (ML) QDs to the larger 3.0-ML QDs due to the coupling effect between the upper and the lower Cd0.6 Zn0.4 Te QDs. The present results indicate that the activation energy in Cd0.6 Zn0.4 TeZnTe double QDs is significantly affected by the ZnTe separation layer.