Nanostructured visible-enhanced CdS/SiO₂/Si heterojunction photodetectors: Synthesis, characterization, and performance optimization

This study examines the effect of molar concentration on the structural, optical, and electrical properties of the nanostructured CdS film prepared by the chemical bath deposition technique. The optical properties show that the energy gap of nanostructured CdS increases from 2.27 to 2.57 eV as molarity increases from 0.2 to 0.6 M. The optoelectronic properties of a CdS/Si heterojunction photodetector prepared at different molar concentrations were investigated. The highest value of figure of merit is 1.5 x 10-4 omega- 1 for CdS film deposited at 0.2 M. The CdS/SiO2/Si photodetector prepared at 0.2 M demonstrated the highest responsivity of 0.34 A/W, specific detectivity of 1.1 x 1012 Jones at 550 nm, and external quantum efficiency of 80% at 500 nm. The fast response time was found for photodetector fabricated at 0.2 M.