In situ electron beam irradiation-driven formation of quantum dots

Abstract

Recrystallization of amorphous materials is a very interesting phenomenon, but some transformation details are still unknown. Here, we report the formation of ZnO quantum dots (QDs) under electron beam irradiation and a series of in situ consecutive observations on the formation processes. When suffering from the irradiation inside a transmission electron microscope, the amorphous hollow nanoparticles, fabricated through treating the Zn–ZnO core–shell samples, synthesized by laser ablation in liquid with tartaric acid, were found to gradually collapse, and crystallization occurred at the same time. These two isochronous processes collectively induced the formation of the QDs. Interestingly, the size of the QDs can be controlled by the applied precursor particles and beam energy. Numerical simulations demonstrated that the thermal shear stresses greatly stimulate the deformation process, resulting in QD formation.