Influence of temperature and excitation density on carrier dynamics in CdZnTe quantum dots

This study investigates the carrier dynamics of self-assembled CdZnTe quantum dots (QDs) using time-resolved photoluminescence measurements, specifically focusing on the effects of temperature and excitation density. Thermally activated transitions with a localization energy of approximately 8 meV are observed at low temperatures, shedding light on the quantum dynamical trajectories of carriers within the QDs. Our results demonstrate that quantum confinement influences both exciton-acoustic phonon and exciton-longitudinal optical (LO) phonon interactions, even under resonant conditions where the average occupancy is less than one electron-hole pair per dot. Multi-phonon absorption processes, particularly those involving LO phonons with energies around 19.2 meV, are identified as key contributors to carrier dynamics, alongside Auger recombination at high excitation densities. The Auger recombination coefficient (C_a) confirms the critical role of phonon-assisted mechanisms in Auger processes. These findings deepen our understanding of the optical behavior of CdZnTe QDs and provide valuable guidance for optimizing their applications in electronic and optoelectronic devices.