THE EFFECT OF pH ADJUSTMENTS ON THE STRUCTURAL AND OPTICAL PROPERTIES OF CIAS THIN FILMS
Keywords:
Thin Films, X-ray Diffraction, Crystal structure, CBD (Chemical Bath Deposition), CIAS (Cu(InAl)Se2)Abstract
Cu(In1-xAlx)Se2 (CIAS) thin films were prepared by the economical chemical bath deposition (CBD)technique on well-cleaned glass substrates. Two different thickness films were prepared by varying the pH. The thickness of the films was measured by gravimetric technique. The structure, morphology, composition, and optical transition of the prepared films were determined. X-ray diffraction studies confirmed the polycrystalline nature of the thin films with a chalcopyrite structure. The structural parameter such as lattice constants, axial ratio, tetragonal distortion, crystallite size, dislocation density, and number of crystallites per unit area has also been evaluated.Scanning electron microscopy studies revealed that the morphology of the prepared films was smooth, dense, uniform, and granular. The composition of various constituents such as Cu, In, Al, and Se in the CIAS films has been determined from energy dispersive X-ray (EDX) analysis. The optical properties have been studied in detail from the transmittance spectra in the visible and nearinfra-red region and the optical transition has been found to be direct and allowed with the bandgap of around 1.4 eV Due to the pH adjustment, the changes in the preferential orientation on the structural properties and the band gap variation with respect to thickness on the optical properties have also been discussed.
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