Structural, Morphological, and Photocatalytic Comparison of TiO₂ Thin Films Deposited by RF Magnetron Sputtering at Room Temperature and 300 °C

In this study, titanium dioxide TiO₂ thin films were deposited onto glass substrates at room temperature and at a substrate temperature of 300°C using the RF magnetron sputtering technique, and their structural, morphological, chemical, and photocatalytic properties were comparatively investigated. XRD analysis revealed that the film deposited at room temperature exhibited a fully amorphous structure, whereas the film deposited at 300°C displayed low-intensity reflections of the anatase (101) and (004) planes on an amorphous background, indicating the onset of limited crystalline nucleation with increasing temperature. Cross-sectional SEM images confirmed the formation of a homogeneous layer with an approximate thickness of 330 nm, while surface SEM micrographs showed a compact and fine-grained morphology characteristic of films deposited at low temperatures. AFM measurements demonstrated a granular surface topography with an RMS roughness of approximately 26 nm over a 10 × 10 µm scan area. FTIR spectra revealed the characteristic Ti–O–Ti vibrational modes, confirming the formation of the TiO₂ network structure. Photocatalytic experiments showed that the TiO₂ film deposited at 300°C achieved approximately 74% degradation of methylene blue under UVA irradiation after about 9 hours, exhibiting significantly higher photocatalytic activity compared to the room-temperature film. This improvement is attributed to partial structural ordering and increased surface roughness. Overall, the findings demonstrate that the structural evolution occurring in TiO₂ thin films deposited at low temperatures directly influences their photocatalytic behavior, and that TiO₂ films exhibiting considerable photocatalytic performance can be produced even at moderate deposition temperatures such as 300°C.