Spatial mapping of optical constants and thickness variations in ITO films and SiO2 buffer layers

In this work, we present detailed spectroscopic ellipsometry (SE) measurements across thirty indium tin oxide In 2 O 3 -SnO 2 (ITO) substrates, providing insights into variations in the complex refractive index for the same commercial ITO material. This study includes an analysis of the distribution of ITO surface roughness, ITO thickness, SiO 2 buffer layer thickness, and the complex refractive index of ITO including electrical resistivity and its gradient. The SE mapping, conducted over a (1.5×1.5) cm scan area on multiple substrates of (2.5×2.5) cm size, reveals uniformity in above parameters within single ITO substrate. However, substantial thickness variations in the SiO 2 buffer layer along with fluctuations in the of ITO are observed across the set of substrates. Our findings underscore the importance of individually assessing each ITO substrate’s optical properties prior to additional layer deposition, as this precision is essential for reliable investigations of other materials, such as organic compounds in OLEDs, in both ex-situ and in-situ studies. Additionally, this article provides comprehensive optical property data for ITO substrates consisting of soda lime float glass coated with a thin SiO 2 buffer layer. • 1.Comprehensive Mapping of Optical Properties : Detailed spectroscopic ellipsometry (SE) analysis of 30 ITO substrates reveals significant variations in the complex refractive index ( ), particularly in the UV and IR regions, highlighting localized inhomogeneities. • Evaluation of Substrate Uniformity : Uniformity in the visible spectral range was confirmed, while edge effects and variations in the SiO 2 buffer layer thickness and of ITO were more pronounced, underscoring the importance of substrate-specific assessments. • Advanced Characterization Methodology : Multi-point SE mapping provides a deeper understanding of spatial variations across substrate surfaces, offering better precision for subsequent optical modeling. • Impact on Thin Film Applications : Findings emphasize the need for accurate characterization of ITO substrates to ensure reliable optical and electronic performance in applications such as OLEDs. • Data for Optical Modeling : Provides comprehensive optical property data for ITO and SiO 2 layers, aiding accurate evaluations of complex multilayer stacks.