1：Experimental Design and Method Selection:

LiTaO3 thin films were prepared on Pt/Ti/SiO2/Si(100) substrate by RF magnetron sputtering and annealed at temperatures varying from 550 °C to 700 °C. The structural and optical properties were investigated using FESEM, GAXRD, XPS, Raman spectrum, and spectroscopic ellipsometry.

2：Sample Selection and Data Sources:

The target material was a calcined compressed ceramic powder with a purity of 99.9% and its Li/Ta mol ratio was 50/

3：9% and its Li/Ta mol ratio was 50/List of Experimental Equipment and Materials:

50. 3. List of Experimental Equipment and Materials: RF magnetron sputtering apparatus (FJL560, SKY Technology Development Limited Company of Chinese Academy of Sciences), field emission scanning electron microscope (S4800), x-ray diffractometer (Xpertpro-MPD), x-ray photoelectron spectroscopy (Escalab 250Xi), Raman spectrometer (Invia Reflex), spectroscopic ellipsometry (SE200-MSP).

4：Experimental Procedures and Operational Workflow:

The films were deposited using an RF power of 150 W at 0.8 Pa total deposition pressure, with O2 flow of 40 sccm and Ar flow of 10 sccm. After deposition, films were annealed at 550 °C to 700 °C for 60 min under O2-rich ambience.

5：8 Pa total deposition pressure, with O2 flow of 40 sccm and Ar flow of 10 sccm. After deposition, films were annealed at 550 °C to 700 °C for 60 min under O2-rich ambience. Data Analysis Methods:

5. Data Analysis Methods: Optical constants and optical band gap energy Eg were deduced by theoretically fitting experimental ellipsometric spectra with the Forouhi-Bloomer dispersion model.