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Abstract
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In the present study, the chemical bath deposition technique was used to prepare pure CdS and Fe-doped (0.4,
0.5, and 0.6 mM) CdS nanostructured thin films. The deposition time, bath pH, and bath temperature were
adjusted at 2 h, 11, and 80 ᵒC, respectively. The prepared thin films were then exposed to gamma irradiation.
Different gamma doses (10, 20, and 30 kGy) were irradiated to investigate how they would affect the optical,
morphological, and structural characteristics of the samples. The prepared thin films were characterized with
various analytical methods including X-ray diffraction (XRD), UV–vis absorption spectroscopy, photoluminescence
(PL) emission spectroscopy, energy dispersive X-ray analysis (EDX), and scanning electron microscopy
(SEM). The XRD patterns confirmed the two-phase nature of all the pure and Fe-doped CdS samples,
which had hexagonal and cubic structures with strong (002) and (111) preferred orientations before and after
gamma irradiation, respectively. The investigation of the surface morphology using SEM images showed the
nanocrystalline nature of the films. The mean grain sizes were obtained to be 37.92–47.71 nm and 36.60–42.50
nm for the non-irradiated and irradiated pure CdS and Fe-doped CdS films, respectively. The decrease (increase)
in the grain sizes of the films were observed with increasing Fe concentration (irradiation dose). The EDX
analysis confirmed the presence of Fe atoms in the samples. The optical properties including absorption, band
gap, extinction coefficient, and PL were studied. It was observed that all the investigated parameters were
affected by Fe doping and gamma irradiation. The variation of Eg is estimated within the ranges 2.47–2.28 eV for
the pure, 2.44–2.06 eV for the 0.4-mM Fe-doped, 2.4–2.17 eV for the 0.5-mM Fe-doped, and 2.36–2.16 eV for the
0.6-mM Fe-doped CdS films before and after irradiation at 10, 20, and 30 kGy doses. The direct optical band gap
decreased as the gamma dose and Fe concentration incr
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