Effect of Substrate Temperature on the Morphology and Crystallinity of TiO₂ Thin Films Grown by ALD Using TTIP and H₂O

This study investigates the influence of substrate temperature on the morphological and structural characteristics of TiO2 thin films synthesized by thermal ALD using titanium tetraisopropoxide and water as precursors. The substrate temperature was varied from 200 to 275 °C in 25 °C increments. Surface morphology was examined using atomic force microscopy, while the crystalline structure was analyzed by XRD and Raman spectroscopy. It was found that films deposited at 200 °C exhibited an amorphous structure and a smooth, conformal surface with minimal roughness. Increasing the temperature to 225 °C led to the formation of microstructures and the emergence of initial signs of crystallization, accompanied by an increase in surface roughness. At 250-275 °C, a well-defined polycrystalline anatase structure was formed, characterized by grain development and nanostructure agglomeration, as evidenced by the increased intensity of diffraction peaks and higher surface roughness parameters. According to the XRD analysis, the average crystallite size ranged from 32 to 71 nm, depending on the synthesis temperature. The results demonstrate that deposition temperature exerts a comprehensive effect on both the phase composition and surface morphology of TiO2 films, which must be considered for their application in functional nanostructures, photocatalytic systems, sensors, and microelectronic devices.

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