Investigating Local Disorder in ZnSnN₂ with X-ray Absorption Spectroscopy

In this work, we investigate the local bonding environment in sputtered ZnSnN₂ thin films using X-ray absorption near-edge spectroscopy (XANES). ZnSnN₂ has recently shown promise for photovoltaic applications, offering potentially groundbreaking optoelectronic properties with the use of cation site disorder to tune the bandgap. However, questions remain about the connection between local coordination environment and long-range disorder in ZnSnN₂. In particular, it has been predicted that different types of local disorder may exist, but these are difficult to distinguish. Oxygen incorporation has also been observed to impact optoelectronic properties, but its bonding structure has not been studied. Here, we probe atomic environment in combinatorial ZnSnN₂ samples with N and O k-edge XANES. Prominent spectral features are compared to partial density of states calculations and reference compounds. Finally, XANES results are related to structural characterization in order to understand the mechanisms behind cation disorder and off-stoichiometry. This work provides a new understanding of the local environment in ZnSnN₂ and demonstrates the use of XANES to probe disorder in II-IV-Ns.