Theoretical and Experimental Comparison of the Properties of Hexagonal Wurtzite ZnO

In this study, the optical and electronic properties of ZnO thin films were systematically investigated using both experimental methods and density functional theory (DFT) calculations. Structural optimizations and electrofilmnic property analyses were conducted using the PBE exchange–correlation functional. The results confirm that ZnO is a direct band gap semiconductor; however, the theoretically calculated band gap (0.87 eV) was significantly lower than the experimentally determined value (3.40 eV), consistent with the well-known underestimation problem of conventional DFT. This highlights the necessity of employing advanced computational methods such as hybrid functionals or GW corrections for precise band gap estimations. Despite the numerical discrepancy in band gap values, a strong spectral agreement was observed between the theoretical and experimental optical parameters, including the absorption coefficient, extinction coefficient, refractive index, and dielectric constants. Both methods indicated prominent optical transitions around 3.2–3.4 eV, especially in the UV region. Additionally, XRD and SEM analyses revealed high crystallinity and a homogeneous nanostructured morphology.