Interlayer coupling and exciton dynamics in vertically stacked CdZnTe/ZnTe quantum dots

We are happy to announce that Dr. Man Minh Tan and colleagues recently published their work entitled "Interlayer coupling and exciton dynamics in vertically stacked CdZnTe/ZnTe quantum dots" in the Journal of Luminescence.

Abstract:

We present a comprehensive investigation of carrier relaxation dynamics in vertically stacked CdZnTe/ZnTe quantum dots (QDs) with varying degrees of interlayer coupling. Using steady-state and time-resolved photoluminescence (PL) spectroscopy across a range of temperatures, we identify distinct recombination pathways that evolve from independent dot behavior to strongly hybridized excitonic states. In weakly coupled stacks, carrier transfer occurs via phonon assisted tunneling from the lower to the upper QD layer, resulting in spectrally resolved peaks with asymmetric linewidth evolution. In contrast, strongly coupled structures exhibit a single, broadened PL band with energy-dependent decay profiles indicative of miniband formation and wavefunction delocalization. To interpret these behaviors, we introduce a unified physical model that explicitly distinguishes tunnelling-in and tunnelling-out processes, each described by temperature-activated sigmoidal dynamics. This framework links key observables such as the interdot transfer rate k_T(T), the tunnelling-induced broadening parameters γ_in and γ_out, the effective recombination lifetime τ_eff(E,T), and the activation energy E_T across spectral, thermal, and temporal domains. These findings provide detailed insight into carrier behavior in semiconductor QD heterostructures when they are influenced by coupling.