Substrate Temperature Dependence of Surface Morphology and Structure of N-Type Fe2O3 Thin Films With Enhanced Transparency

Abstract

This work reports the effect of substrate temperature (T_S) on the structure, surface morphology, optical, and electrical properties of iron (III) oxide (Fe₂O₃) thin films. Fe2O3 thin films were deposited from the aqueous solution of ferric chloride hexahydrate at various TS between 573 and 773 K using the spray pyrolysis technique. In field emission scanning electron and atomic force microscopic analysis, the surface of Fe₂O₃ films comprised nanoparticle clusters. In X-ray diffraction analysis, Fe₂O₃ thin films showed a rhombohedral-hexagonal structure with the predominant orientation along (104) crystallographic plane. Crystallite size reduced from 28 to 13 nm with the increase of TS between 573 and 773 K. In UV-vis- NIR spectroscopy, the highest transmittance was found to be 76% for the film deposited at the TS of 673 K. Band gap of the film was obtained between 2.05 - 2.09 eV. The electrical resistivity of the films ranged from 2.2 ´ 105 to 9.0 ´ 105 Ω-cm. The films contained n[1]type majority carriers with carrier concentration in the order of 1018 cm-3 . Fe₂O₃ thin films with wide band gap, high transparency, and n-type conductivity indicate that the films are suitable for Fe₂O₃ in optoelectronic applications.

Bangladesh Journal of Physics, Vol. 30, Issue 1, pp. 13–22, June 2023