Design of Experiments (DoE) Approach for Optimizing the Processing and Manufacturing Parameters of SnO2 Thin Films via Ultrasonic Pyrolytic Deposition

This work employed a design-of-experiments (DoE) strategy, specifically a 23 full factorial design, to assess how suspension concentration (0.001–0.002 g/mL), substrate temperature (60–80 °C), and deposition height (10–15 cm) influence tin dioxide (SnO2) thin films produced by ultrasonic spray pyrolysis (USP). The response variable was the net intensity of the principal diffraction peak, used as an operational metric for detecting the deposited phase. All patterns matched the SnO2 phase cassiterite reference without impurity peaks. Statistical analyses (ANOVA, Pareto and half-normal plots, and response surface methodology, RSM) identified suspension concentration as the most influential factor, followed by significant two- and three-factor interactions. The model exhibited a high coefficient of determination (R2 = 0.9908) and low standard deviation (12.53), validating its predictive capability. The optimal deposition process was achieved at the highest suspension concentration (0.002 g/mL), lowest substrate temperature (60 °C), and shortest deposition height (10 cm). These results demonstrate the utility of full factorial DoE for quantifying and controlling deposition outcomes in USP and provide a robust statistical framework to guide the synthesis of SnO2 thin films.