<p>In this study, an Al₂O₃ interfacial layer was fabricated on n-type Si substrates via a sol–gel route and integrated into Au/ Al₂O₃/n-Si/Al Schottky diodes. The structural, morphological, and electrical properties of the Al₂O₃ thin film and their influence on charge transport and interface-state dynamics were investigated. X-ray diffraction (XRD) revealed the coexistence of dominant α- Al₂O₃ and transition alumina phases, indicating partial phase transformation and structural disorder. FE-SEM and EDS confirmed a uniform, dense morphology with homogeneous elemental distribution; however, combined with XRD results, these findings suggest nanoscale inhomogeneities, including phase boundaries and crystallographic defects. Electrical characterization was performed using <i>I</i>–<i>V</i>, <i>C</i>–<i>V</i>, and <i>G</i>–<i>V</i> measurements. The diode exhibited strong rectification with a barrier height of ≈0.85 eV and an ideality factor of ≈2.30, indicating non-ideal transport dominated by interface states and the Al₂O₃ interfacial layer. Charge transport behavior evolves from ohmic-like conduction to SCLC-like and trap-influenced transport regimes. Under reverse bias, the low-field transport behavior is found to be more consistent with Schottky-emission-like conduction, while trap-assisted processes become increasingly significant at higher electric fields. The interface state density (<i>N</i>_<i>ss</i>), evaluated using Hill–Coleman and high–low frequency methods, was on the order of 10¹²eV⁻¹cm⁻² with strong energy and frequency dependence. Frequency-dependent C^-2–V analysis showed that donor concentration, barrier height, and depletion width are influenced by interface states and interfacial polarization. Overall, the structural and electrical results reveal a physically consistent qualitative relationship between sol–gel-derived microstructural features and the observed non-ideal device characteristics.</p> Graphical Abstract <p></p>