Energy gap: refractive index in ZnO/Fe/ZnO multilayer prepared by ALD and DC

Abstract The present work provides a mathematical formulation for the optical energy gap-refractive index relations of Fe layer with different thickness, inserted between two layers of ZnO in the form of ZnO/Fe/ZnO thin film system. The thin films having a multilayer of ZnO/Fe/ZnO have been grown on glass substrates, using atomic layer deposition and DC magnetron sputtering. The crystalline structure of the multilayer thin films was carried out by the X-Ray diffraction while the thickness data and the quality of the layers were checked by using a prepared lamella for each sample using focused ion beam (FIB). The extinction coefficient ( k ) of the thin film samples was used to calculate the energy band gap ( E g ) . An explanation for the dependence of Fe interlayer thickness (20, 40, 60 and 80nm) between upper and lower layer of ZnO(80nm) on the optical energy gap and refractive index (n) of the thin film samples and their relationship are presented and discussed using different theories. With increasing the Fe interlayer thickness, the evaluated band gap showed a decrease from 3.77eV to 3.43 eV, while the calculated refractive index was found to increase from 2.20 to 2.27. The optical conductivity, optical dielectric constant, dielectric susceptibility, electronic polarizability, electronegativity, optical basicity and metallization criterion were obtained by several calculations based on the refractive index. By fixing the ZnO thickness and varying the Fe thickness, we can isolate the effects of Fe thickness on the optical properties of ZnO/Fe/ZnO system. The fixed thickness of ZnO enable direct comparison of the optical properties and related parameters across different Fe thickness and hence enabling the design of materials with specific potential applications. Further derivations based on the energy gap – refractive index relations discussed in the context, indicates that the insertion of a metallic layer into oxide layer have high potential that could enhance the quality of remarkable optical properties of ZnO thin film, to be applied for memories applications and allows the performance of the devices, to be optimized.in many industrial and consumer products.