1：Experimental Design and Method Selection:

The study used thermal evaporation for thin film deposition, followed by structural characterization using XRD, EDS, and Raman spectroscopy, and optical characterization via temperature-dependent transmission measurements. Theoretical models (Varshni and O'Donnell-Chen) were applied to analyze band gap energy variation with temperature.

2：Sample Selection and Data Sources:

CdS thin films were grown on ultrasonically cleaned soda-lime glass substrates using high-purity CdS single crystals. Data were collected from transmission spectra in the 400–1050 nm range at temperatures from 10 to 300 K.

3：List of Experimental Equipment and Materials:

Equipment includes Rigaku miniflex diffractometer (XRD), ZEISS EVO 15 SEM with EDAX detector (EDS), Horiba Jobin Yvon RMS-550 Raman spectrometer, Shimadzu UV 1201 spectrophotometer, Advanced Research Systems Model CSW-202 cryostat, Inficon XTM/2 quartz crystal monitor, Dektak 6 M thickness profilometer. Materials include CdS powder, alumina-coated tungsten boat filament, soda-lime glass substrates.

4：Experimental Procedures and Operational Workflow:

Thin films were deposited by thermal evaporation at room temperature under vacuum. XRD, EDS, and Raman measurements were performed at room temperature. Transmission measurements were conducted at various temperatures using the cryostat. Data analysis involved calculating absorption coefficient and using derivative spectrophotometry.

5：Data Analysis Methods:

Band gap energies were determined using Tauc relation for direct transitions and derivative spectrophotometry. Fitting was done with Varshni and O'Donnell-Chen models to extract parameters like average phonon energy and electron-phonon coupling.