1：Experimental Design and Method Selection:

The study involves preparing CZTS films by sulphurizing electron beam deposited metallic precursors in different environments (elemental S powder and 5% H2S + N2 gas) at various ramping rates (1, 5, and 10°C/min) at 500°C for 1 hour. The rationale is to understand how sulphurization conditions affect phase formation and minimize secondary phases.

2：Sample Selection and Data Sources:

Soda lime glass substrates are used. Metallic precursors (Cu, Zn, Sn of

3：9% purity) are deposited with specific thicknesses (Cu:

180 nm total, split as 90 nm layers; Zn: 160 nm; Sn: 230 nm) to achieve Zn-rich, Cu-poor composition.

4：List of Experimental Equipment and Materials:

Equipment includes an electron beam evaporator (accelerating voltage 3.3 kV, substrate rotation 50 RPM, base pressure 5×10^{-6} mbar), quartz crystal thickness monitor, X-ray diffractometer (Bruker Discover D8 with CuKα radiation), Raman spectrometer (Bruker Senterra with 532 nm laser), field emission gun scanning electron microscope (Carl Zeiss Supra-S5), energy dispersive X-ray spectrometer (Oxford Instrument), and UV-Vis spectrophotometer (Varian 5000). Materials include elemental S powder, 5% H2S + N2 gas, N2 carrier gas, and cleaning solvents (acetone, methanol, ethanol, deionized water).

5：3 kV, substrate rotation 50 RPM, base pressure 5×10^{-6} mbar), quartz crystal thickness monitor, X-ray diffractometer (Bruker Discover D8 with CuKα radiation), Raman spectrometer (Bruker Senterra with 532 nm laser), field emission gun scanning electron microscope (Carl Zeiss Supra-S5), energy dispersive X-ray spectrometer (Oxford Instrument), and UV-Vis spectrophotometer (Varian 5000). Materials include elemental S powder, 5% H2S + N2 gas, N2 carrier gas, and cleaning solvents (acetone, methanol, ethanol, deionized water). Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: Substrates are cleaned by ultrasonication. Metallic layers are deposited via electron beam evaporation. Precursor films with stacking sequences glass/Cu/Zn/Sn/Cu (CZTC) and glass/Cu/Sn/Zn/Cu (CTZC) are sulphurized in a tube furnace at specified conditions. Characterization is performed using XRD, Raman spectroscopy, FEG-SEM, EDS, and UV-Vis spectroscopy.

6：Data Analysis Methods:

XRD patterns are compared with JCPDS cards. Raman spectra are deconvoluted using Lorentzian function to identify phases. Morphology and composition are analyzed from SEM and EDS. Optical bandgap is determined from Tauc plots using (αhν)^2 vs. photon energy for direct allowed transitions.