Correlation between thickness-dependent morphology, phase structure, and vibrational properties of TiO2 thin films deposited via DC magnetron sputtering: A multi-technique characterization approach

In this study, the physicochemical properties of TiO₂ thin films with varying thicknesses (72 nm, 125 nm, and 283 nm) were systematically investigated using Raman and infrared (IR) spectroscopy. The results reveal that increasing film thickness enhances the structural coherence of anatase and rutile phases, intensifies phonon resonance, and reduces surface chemical modifications. Raman spectroscopy proved effective for assessing crystallinity and morphological integrity, while IR spectra provided detailed analysis of the stretching and bending vibrations of Ti–O and Ti–O–Ti bonds. Mechanical stress and the presence of chemical surface groups were detected in the 700–800 cm⁻¹ spectral region. These findings underscore the critical role of thickness and surface state control in optimizing TiO 2 thin films for high-performance photocatalytic and optoelectronic applications.