Relating Electronic and Geometric Structure of Atomic Layer Deposited BaTiO₃ to its Electrical Properties

Atomic layer deposition allows the fabrication of BaTiO₃ (BTO) ultrathin films with tunable dielectric properties, which is a promising material for electronic and optical technology. Industrial applicability necessitates a better understanding of their atomic structure and corresponding properties. Through the use of element-specific X-ray absorption near edge structure (XANES) analysis, O K-edge of BTO as a function of cation composition and underlying substrate (RuO₂ and SiO₂) is revealed. By employing density functional theory and multiple scattering simulations, we analyze the distortions in BTO's bonding environment captured by the XANES spectra. The spectral weight shifts to lower energy with increasing Ti content and provides an atomic scale (microscopic) explanation for the increase in leakage current density. Differences in film morphologies in the first few layers near substrate-film interfaces reveal BTO's homogeneous growth on RuO₂ and its distorted growth on SiO₂. This work links structural changes to BTO thin-film properties and provides insight necessary for optimizing future BTO and other ternary metal oxide-based thin-film devices.