Synthesis and characterization of iron interlayers as modulators of optical and dielectric performance in ZnO thin films

Abstract This work explores the influence of Fe interlayer thickness on the morphology, optical, and dielectric behavior of ZnO-based multilayer film prepared by a combined ALD-DC technique. Morphology was analyzed using focused ion beam (FIB) and energy-dispersive X-ray spectroscopy (EDX), while optical properties were evaluated through transmittance and reflectance measurements. The prepared lamellae confirmed well-defined thickness of each individual layer, and (EDX) confirmed the absence of other elements present in the thin-film samples under study. According to the results presented in the obtained figures, the increase of the Fe thickness in ZnO/Fe/ZnO system leads to a decrease in transmittance and an increase in reflectance, refractive index ( n ), extinction coefficient ( k ), and reflectivity ( R ref ). Both the real and imaginary parts of the dielectric constant (ε 1 & ε 2 ) , as well as the dielectric loss (tanδ) increases with Fe content, while the optical quality factor (Q) decreases. Moreover, the carrier concentration to effective mass ratio (N/m * ) and both optical and electrical conductivity (σ opt & σ elec ) increases, whereas the electrical modulus (M * ) decreases with increasing Fe thickness . The Wemple-DiDomenico single-oscillator (WDD) model was employed to determine the dispersion parameters, from which the nonlinear refractive index (n 2 ) and third-order nonlinear susceptibility (Χ (3) ) was estimated. These results highlight the significant role of Fe in tailoring the optical and dielectric properties of ZnO-based ͌͂ opto-electronics applications.