Energy of excitons and acceptor–exciton complexes to explain the origin of ultraviolet photoluminescence in ZnO quantum dots embedded in a SiO2 matrix

Assuming finite depth and within the effective mass approximation, the energies of exciton states and of the acceptor–exciton complexes confined in spherical ZnO quantum dots (QDs) embedded in a SiO2 matrix are calculated using a matrix procedure, including a three-dimensional confinement of carrier in the QDs. This theoretical model has been designed to illustrate the two emission bands in the UV region observed in our experimental Photoluminescence spectrum (PL), with the first emission band observed at 3.04 eV and attributed to the bound ionized acceptor–exciton complexes, and the second one located at 3.5 and assigned to the free exciton. Our calculations have revealed a good agreement between the matrix element calculation method and the experimental results.

► The nature of the UV photoluminescence from ZnO QDs itself is not fully understood.
► Numerical calculations performed to explain the origin of the UV PL in our ZnO QDs.
► We demonstrated a strong tunability of the optical properties of ZnO QDs with size.