Shell Phase and Morphology Control for Emission Tuning in III-V Core/Shell Quantum Dots.

Epitaxial growth of shells on III-V semiconductor quantum dot (QD) cores yields improved fluorescence quantum efficiency and stability toward their implementation in light emission technologies. Here, we control the shell morphology and crystal structure and investigate their effects on the emission properties of heterovalent III-V/II-VI core/shell QDs. This is achieved by tuning the ZnSe shell growth mode from kinetic to thermodynamic regimes via adjusting the precursor reactivity. When combined with high-temperature Ostwald ripening, this approach enables controlled tuning of shell morphology between tetrahedral and spherical-like, accompanied by a transformation of the shell crystal structure from zinc-blende to wurtzite. The position of the III-V cores within the III-V/ZnSe core/shell QDs varies under the different growth modes, being closer to the edge in the former. Moreover, the spherical architecture exhibits a higher photoluminescence quantum yield (PLQY) and improved stability. Such morphological and crystal-type differences directly affect the band alignment and exciton confinement, leading to tunable emission spectra and exciton dynamics, as confirmed by quantum mechanical simulations of the band gap exciton energies. This study deepens the understanding of heteroepitaxial growth and emission control in III-V/II-VI core/shell QDs, enabling advanced QD design toward optimization for diverse light emission applications.