1：Experimental Design and Method Selection:

Sol–gel derived KNN thin films were deposited using a solution with 5% of potassium excess on Pt/TiO2/SiO2/Si and Pt/SrTiO3 substrates, and rapid thermal annealed at 750 ?C for 5 min.

2：Sample Selection and Data Sources:

Identical polycrystalline crack-free ~335 nm-thick KNN films were produced from

3：2 M precursor solutions with 5% of potassium excess by RTA at 750 ?C on platinized Si and SrTiO3 substrates. List of Experimental Equipment and Materials:

X-ray diffractometer, SEM, EDS system, precision LCR meter, ferroelectric analyzer, AFM.

4：Experimental Procedures and Operational Workflow:

The films were characterized by XRD, SEM, EDS, dielectric and ferroelectric measurements, and AFM.

5：Data Analysis Methods:

XRD analysis for phase formation and assemblage, SEM for morphology and thickness, EDS for compositional analysis, dielectric and ferroelectric measurements for electrical properties, and AFM for roughness and PFM characterization.