Influence of ZnTe separation layer thickness on optical properties in CdTe/ZnTe double quantum dots on Si substrates

•Influence of ZnTe separation layer thickness in double quantum dots were investigated.•Photoluminescence dynamic probed the electric field screening effects.•Separation layer thickness plays a key role in the intermixing and thermal escape effects.•Carrier dynamics of double quantum dots are evaluated by different models.•Thermal escape is assisted by multiple phonons with energy of 19.1–21.3 meV. We investigate the influence of the ZnTe separation layer thickness on the photoluminescence (PL) dynamics of CdTe/ZnTe double quantum dots (DQDs) on Si substrates. The results clarify that the DQD's structure effectively improves the limit of the carrier collection and the thermal stability of the corresponding single-layer QDs. The unusual temperature-dependent PL is explained using the single model for thermal redistribution of carrier states. This model indicates that the main nonradiative process at high temperatures is caused by scattering via multiphonons with longitudinal optical phonon energy of about 19–21.3 meV. The confinement-induced mixing and electron-carrier coupling effects cause blue-shift and enhanced PL intensity. We propose that the separation layer controls carrier dynamics in optoelectronic devices by modulating the thermal escape and e-h pairs in the intermixing layers.