Novel Preparation of Cu2O/CaF2 Nanofilms via Thermal Evaporation Technique: Effect of Thickness on its Energies

Document Type : Research Paper

Authors

1 Department of Physics, College of Education for Pure Sciences, University of Babylon, Hilla, Iraq

2 Department of Physics, College of Education for Pure Sciences, University of Babylon, Iraq

Abstract

The novelty of preparation nanofilms makes the manufacturers choose the new property of the film for new applications or for economic purposes. Cu2O:CaF2 nanofilms were successfully prepared by thermal evaporation technique for the first time with different thicknesses (35, 42,50, and 57 nm). The structural, morphological, optical, and dispersion properties were investigated. The X-ray diffraction (XRD) results showed that the prepared films were amorphous. With increasing thickness, the peak exhibited at 24.2º, which attributed to the CaF2 that corresponded to the (111) with face center cubic (FCC). Atomic force microscopy (AFM) confirmed that the films grown by this technique had a good homogeneous surface. The roughness average, root mean square value, and average grain diameter increased with the increasing thickness. The optical properties results showed that the transmittance and energy gap decreased with the increase of thickness, while the absorption coefficient, real and imaginary of dielectric constant decreased. The Cu2O:CaF2 thin films have allowed a direct energy gap (Eg) that was decreased from 3.54 to 3.34 eV with the increase of thickness. The dispersion parameters such as; Eo, Ed, no, ε∞, M−1, and M−3 were calculated using the Wemple–DiDomenico model. The value of the energy gap estimated by Wemple–DiDomenico calculations was consistent with the value obtained from the Tauc relation and found that the parameters were decreased with the increase of thickness.

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