1：Experimental Design and Method Selection:

The BFO film is fabricated using a conventional chemical solution deposition method. The crystalline phase of the BFO film is determined by x-ray diffractometer. The optical properties of the film are analyzed by diffused reflectance spectroscopy. The surface morphology, piezoelectric phase, and amplitude, and ferroelectric domain switching characteristic of the film are recorded using a piezo-response force microscopy.

2：Sample Selection and Data Sources:

The precursor solution is prepared by dissolving bismuth nitrate and iron acetylacetonate powders in acetic acid and 2-methoxy ethanol. The solution is then spin-coated on Pt/TiO2/SiO2/Si substrate.

3：List of Experimental Equipment and Materials:

X-ray diffractometer (Rigaku ? Smart lab, Japan), field emission scanning electron microscopy (FEI ? Inspect F50, USA), piezo-response force microscopy (Park System ? NX10, Republic of Korea), ferroelectric tester (Radiant Technology ? PMF0713-334, USA), laser of wavelength 405 nm, UV?VIS source (Xenon arc lamp, Newport ? 67005, USA), power meter (Coherent ? PM 10, China), high resistance electrometer (Keithley ? 6517B, USA).

4：Experimental Procedures and Operational Workflow:

The precursor solution is spin-coated on substrate and annealed. The film's thickness is measured, and its optical properties are analyzed. The photodetector measurements are performed under various light intensities.

5：Data Analysis Methods:

The performance parameters of the photodetector such as responsivity, detectivity, photoconductive gain, and external quantum efficiency are calculated from the photocurrent.