Study of Undoped and Indium Doped ZnO Thin Films Deposited by Sol Gel Method
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Date
2022-12-27
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JOURNAL OF NANO- AND ELECTRONIC PHYSICS
Abstract
1 wt. % Co-doped ZnO (CZO) thin films of varying thicknesses (3, 5 and 7 layers, which correspond to
403, 545 and 725 nm as thickness) are deposited using the sol-gel method onto glass substrates by dip coating
technique. Zinc acetate dehydrate, cobalt acetate, 2-methoxyethanol and ethanolamine are used as
primary materials, solvent and stabilizer, respectively. The thermally annealed films are characterized to
study the structural, surface morphology, electrical and optical properties. X-ray diffraction (XRD) shows
that these films have a polycrystalline hexagonal structure (wurtzite structure with space group P63mc),
possessing compressive stress and presenting a preferred orientation along the (002) plane. We note that
the particle size increases when the thickness increases. The surface morphology of the prepared CZO thin
films is investigated by atomic force microscopy (AFM). It reveals the emergence of a uniform columnar
structure and shows that the particle size and the root mean square (RMS) of CZO increase with increasing
thickness. UV-visible spectroscopy shows (in the visible region) a transmittance between 75 and 86 %
for all the films, strong absorption (in the UV region) and a decrease in the optical band gap. Moreover, the
near band edge (NBE) and visible emissions detected by photoluminescence are affected by the thickness.
The electrical conductivity of the sample with 725 nm is found to be 4.43 (cm) – 1.