Influence of Deposition Time on Structural, Morphological, and Optical Properties of CdS Thin Films Grown by Low-Cost Chemical Bath Deposition

Abstract

CdS thin films were deposited on glass substrates employing low-cost and low-temperature chemical bath deposition (CBD). The effect of deposition time on the fabricated sample’s properties was investigated by XRD, SEM, EDX, Raman, UV-vis spectrophotometry, and PL spectroscopy. XRD results indicate the formation of cubic and hexagonal structures of CdS thin films. The calculated average crystal size ranged from 21–50 nm. SEM results indicate the formation of hierarchical nanoflakes where the nanoflakes are entangled with one another like plant roots. Raman study confirmed that the fabricated thin films have two distinct peaks that are centered at 298 cm−1 and 599 cm−1, which are characteristic vibration modes for CdS thin film. UV-vis absorption spectra indicate absorption band edges near 500 nm, which are related to the band gap values of CdS thin films. The estimated Eg of CdS thin films was reduced from 2.4 to 2.22 eV as the deposition time increased from 5 to 60 min. PL results show the main peak centered at 537 nm, its intensity decreasing as deposition time increases, indicating lower recombination of charge carriers. Our results reveal that CdS thin films are an excellent candidate for optoelectronic applications.