Revealing Growth Schemes of Nanoparticles in Atomic Resolution: Mapping Stacking Fault Formation and Distribution

Abstract

Controlling the growth process of inorganic nanoparticles, especially the kinetically driven ones, is crucial for designing tailor-made nanoparticles for various applications. Specifically, controlling the formation of stacking faults in semiconductor quantum dots is necessary, since stacking faults were associated with inferior optical performance. Ensemble techniques, such as XRD powder diffraction and optical absorption, can be insensitive to the formation of stacking faults and in certain cases might produce misleading information. Using as a model the thoroughly studied CdSe system, we exploited the well-known unidirectional growth of the Wurtzite phase in order to follow the structural evolution of two different batches of CdSe nanoparticles. We were able to get insight on the crystal growth stages, step by step, employing high resolution electron microscopy and focal series reconstruction. The different kinetics of the two variants were monitored using a statistical approach. The same approach can be used to provide atomic-scale information for any system exhibiting unidirectional growth.