Electronic structure characterization by photoelectron spectroscopy of BaZrS3 perovskite powder and thin film

Chalcogenide perovskites exhibit optoelectronic properties that position them as breakthrough materials in the field of photovoltaics. We report a detailed investigation into the electronic structure and chemical properties (XPS) of polycrystalline BaZrS3 perovskite powder, complemented by an analysis of their geometric atomic arrangement using XRD and XAS. The results are compared with measurements on sputtered polycrystalline BaZrS3 thin film prepared through rapid thermal processing. Moreover, we establish a correlation between the experimental valence band spectra and the theoretical density of states derived from DFT calculations, thereby discerning the orbital constituents involved. While bulk characterization confirms the good quality of the powder, depth-profiling achieved by photoelectron spectroscopy utilizing Al Kα (1.487 keV) and Ga Kα (9.25 keV) radiations shows that, regardless of the fabrication method, the oxidation effects extend beyond 10 nm from the sample surface, with specifically zirconium oxides occurring deeper than the oxidized sulfur species. The hard X-ray photoelectron spectroscopy study on the powder and thin film detects signals with minimal contamination contributions and allows the determination of the valence band maximum position with respect to the Fermi level. Our analysis gives an improved understanding of the electronic structure of BaZrS3, linking the electronic structure of this semiconductor to the fundamental bonding properties of the material, providing knowledge which is crucial for interfaces development, and consequently, for device integration.