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Depositions and characterization of sol–gel processed Al-doped ZnO (AZO) as transparent conducting oxide (TCO) for solar cell application



AbstractAl-doped ZnO (AZO) thin films are deposited on glass substrate by sol–gel spin coating using zinc acetate dihydrate as a precursor with different molar concentrations varying from 0.35 to 0.75 mol/L. To investigate the structural, electrical, optical and morphological properties of AZO films, XRD, four-point probes, HE measurement, UV–Vis spectrometry and SEM with EDX are used. Thickness of the thin film is measured by a surface profilometer. The structural characteristics show a hexagonal wurtzite structure with a (002)-preferred orientation. Optical study reveals that transmittance is very high (up to 90%) within the visible region and optical band gap, Eg varies from 3.25 to 3.29 eV with Zn concentration. The carrier concentration increases and resistivity decreases with the increase in Zn concentration. Thin films fabricated with 0.75 mol/L of Zn concentration exhibit the best electrical property. SEM study shows non-uniform surface of the films where EDX confirms the formation of AZO. The results revealed by this study prompt a high interest to use AZO as transparent conductive oxide for advanced applications such as displays, solar cells and optoelectronic devices.