Synthesis, structure, I–V characteristics, and optical properties of chromium oxide thin films for optoelectronic applications

Abstract

Improving coating technology and thin film formation by optimizing the experimental parameters has become essential for various industrial and technological fields. This work aims to study the influence of the precursor materials on the physical and electro-optical properties of Cr2O3 thin films. The solutions were prepared using the sol–gel route and deposited on glass slides using the spin coating technique. The structure and morphology of the films were studied using XRD, FT-infrared (IR), and field-emission scan-electron microscope. The results indicated the formation of a high-purity Cr2O3 (Eskolaite) phase in the form of spherical nanoparticles with sizes of 17–25 nm. Three bands appear at 490, 765, and 889 cm − 1 {{\rm{cm}}}^{-1} in the FTIR spectra, which are attributed to Cr – O {\rm{Cr}}{\rm{\mbox{--}}}{\rm{O}} / Cr ═ O {\rm{Cr}}{\rm{═}}{\rm{O}} vibrations. The I–V curves showed linear behavior and good ohmic features. Ultraviolet-visible-near infrared spectra showed that the films are highly transparent, with band gaps in the range of 2.60–2.90 eV, and refractive indices in the range of 1.92–2.25. The sheet resistances, the new figure of merit, the real and fictional dielectric constants, and the optical conductivity were discussed. The Cr2O3 thin films are the best candidates for various utilizations, including solar cells, sensors in the IR region, and energy storage.