Methods for Rapid and Smart Characterization of Vanadium Oxide Thin Films and Thermally Aged Samples Using Raman...

Vanadium oxides (VOxs) are technologically important materials because of their versatile properties, including a reversible metal-insulator transition. However, the complex vanadium-oxygen phase diagram includes numerous stable stoichiometries and metastable polymorphs, making material identification challenging. This work presents a data-driven, nondestructive characterization workflow that combines Raman spectroscopy and principal component analysis (PCA) to provide rapid and intelligent feedback during VOx thin-film fabrication. Although Raman spectroscopy provides ultrasensitive chemical information, conventional spectral interpretation requires specialized expertise and extensive reference data. An in-house fabrication protocol based on spin-casting chemical precursors and thermal annealing was developed to produce thin-film standards of VO₂, V₂O₅, V₃O₇, and V₆O₁₃. Raman fingerprints from these standards were used to construct two- and three-dimensional PCA models that distinguish stoichiometric variation and provide interpretable feedback during fabrication-process development. The standards also serve as references for evaluating thermally corroded samples. These results demonstrate that PCA-enabled Raman analysis can serve as an adaptive sensing approach for rapid assessment of VOx stoichiometry, simplified spectral interpretation, and fabrication optimization.