Effect of Deposition Time on the Optoelectronic Properties of CdS Thin Films Synthesized via Chemical Bath Deposition Technique

Simon Ja’afaru, Isaac H Daniel, Yakubu A Tanko, Nicodemus Kure and Olayinka A Babalola
2026-03-27 57 views 3 downloads

 

Cadmium sulphide (CdS) thin films were synthesized via chemical bath deposition (CBD) to investigate the influence of deposition time on their optoelectronic properties. The films were deposited at 80 °C for durations ranging from 5 to 30 minutes. Film thickness increased from 1.5 to 3.0 µm with increasing deposition time, while surface roughness exhibited a non-linear variation associated with nucleation, growth, and grain agglomeration processes. X-ray diffraction of the 30-minute film confirmed a polycrystalline hexagonal CdS structure. Optical analysis revealed a non-linear variation in the bandgap, decreasing from 2.42 eV to 2.07 eV, with strong absorption in the visible region and a maximum absorption at 25 minutes. The refractive index, dielectric constants, and optical conductivity also varied with deposition time, indicating changes in optical response and carrier transport. Hall effect measurements confirmed n-type conductivity, with mobility increasing up to 25 minutes before decreasing, while carrier concentration and resistivity exhibited deposition-time dependence. The 20-minute film had a good mix of optical, electrical, and surface properties. The 30-minute film, on the other hand, had the highest photosensitivity (3110.08%) and responsivity (1.76 × 10?² mA.W?¹). These findings indicate that deposition time is an essential factor for optimizing the optoelectronic performance of CdS thin films for photodetector applications.

 

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