Investigation of the structural, morphological, optical, and electrical properties of thin films: application of effective medium theories to CdO/Co3O4 composites

Abstract

Thin films of cadmium oxide (CdO), cobalt oxide (Co₃O₄), and their composites were deposited on glass substrates at 360 ℃ using the spray pyrolysis method. The films underwent characterization through various techniques, including energy-dispersive X-ray spectroscopy (EDX), scanning electron microscope (SEM), X-ray diffraction (XRD), and ultraviolet–visible spectroscopy (UV–Vis). Hall Effect measurements were also conducted to assess the structural, optical, and electrical properties. The XRD analysis revealed crystalline structures with cubic symmetry for both CdO and Co₃O₄, and the Scherrer equation confirmed their nanomaterial nature. EDX results identified the distinct proportions of oxygen, cadmium, and cobalt in the films. On the other hand, the optical band gaps determined via Tauc plots indicated values of Eg1 = 1.54 eV and Eg2 = 2.01 eV for Co₃O₄, and Eg3 = 2.4 eV for CdO. As for the Hall Effect measurements, they were performed to determine a number of electrical parameters. The results showed that the addition of Co₃O₄ into CdO increased the sheet resistance of the composite. This research has potential applications in various areas, including the design of solar cells (photovoltaic devices) and the creation of new light-based devices (optoelectronic devices). Additionally, the dielectric functions of composites (CdO)_x (Co₃O₄)_1-x with varying compositions (x = 0.7, 0.5, and 0.3) were evaluated. The dielectric properties were experimentally measured from 350 to 2500 nm, and theoretical calculations were performed using mixing equations like Looyenga, Kim, and Bruggman, with the Looyenga model accurately depicting the dielectric properties of the materials studied.