Characterization of Nanocrystallite CdAl2SO3 Thin Films Produced by Inexpensive Chemical Bath Techniques for Photonic Device Applications: The Influence of Annealing Temperature


J. Ezihe, D. D. O. Eya, C. Iroegbu, O. K. Echendu, K. O. Egbo

Quaternary nanocrystallite (CdAl2SO3) thin films have been synthesized by the method of chemical bath deposition (CBD) technique using a reaction bath containing cadmium chloride, thiourea, and Aluminium sulphate octadecahydrate at room temperature. The thin films are white in colour and strongly adherent to the substrate. The materials were annealed at various temperatures of 150 °C, 200 °C, and 250 °C before characterizing. The XRD results showed that the CdAl2SO3 thin films crystallize as binary-phase compounds of CdSO3 and Al2O3. The material has good absorbance at room temperature compared to annealed temperature. Annealing has little or no effect on the transmittance of the film material. The absorption coefficient increases with annealing temperature. The reflectance decreases with annealing temperature. The direct bandgap of the CdAl2SO3 thin films ranges from 3.70eV to 3.9eV. The thickness of the films ranges from 207 nm to 879 nm. The SEM micrographs reveal homogenous and densely packed grains with unequal sizes and shapes. The high absorption in the UV-Vis regions makes the material suitable for thin films absorber solar cells. The direct bandgap of the thin films makes them applicable in optical devices such as LEDs and semiconductor lasers.


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