STROBE Seminar: Dr. Gordana Dukovic Presents ‘Elemental distribution and local electronic structure in oxynitride nanocrystals’

Zinc-gallium oxynitride (Ga1-xZnx)(N1-xOx) exhibits visible absorption with a band gap that depends on composition (i.e., the value of x) and has been demonstrated to split water under visible irradiation. The origin of visible absorption in this solid solution material in this material is not understood. Furthermore, the local atomic-level distribution of the 4 elements, Ga, Zn, N, and O may play an important role in the optical properties of (Ga1-xZnx)(N1-xOx).

This presentation will focus on our use of scanning transmission electron microscopy (STEM) tools to characterize the local composition and electronic structure of these particles. I will describe the elemental distribution within (Ga1-xZnx)(N1-xOx) nanocrystals, measured by Energy Dispersive X-ray Spectroscopy (EDS) with sub-nm resolution, as well as the methods to control compositional disorder. Furthermore, I will describe our ongoing efforts to use Electron Energy Loss Spectroscopy (EELS) to correlate local composition with local electronic structure and elucidate the relationship between the two. Together, these tools allow us to postulate a comprehensive picture of the optical properties of (Ga1-xZnx)(N1-xOx) nanocrystals.