Characterization of photoconductive CdS thin films prepared on glass substrates for photoconductive-sensor applications

Cadmium sulfide (CdS) thin films with n-type semiconductor characteristics were prepared at room temperature on glass substrates by radio-frequency magnetron sputtering for photoconductive-sensor applications. Films deposited at room temperature exhibit polycrystalline phases and show smooth surface morphologies. The deposition rate of the films decreases with increasing working pressure. The dark- and photoresistances in 400-nm-thick CdS films deposited at 6.7×10^-1 Pa and 80 W were approximately 1×10⁵ and 3×10⁴ Ω/sq, respectively. Lowering both the dark- and photoresistances lowers the sensitivity (R_dark/R_photo) of the resistance.