Structure–defect–reliability engineering of composition-tuned TiO₂ and NiTiO₃ thin films for advanced MOS applications

Abstract Oxide dielectric materials offer an effective strategy to control defect density and enhance MOS device reliability. This research focused on sol–gel-derived TiO₂ and NiTiO₃ thin films, which were synthesized and microwave annealed to investigate structure–defect–reliability correlations. XRD, SEM, and AFM analyses confirmed improved crystallinity and reduced surface roughness after composition tuning. Interface trap density decreased from ~ 1.5 × 10¹² to ~ 6 × 10¹¹ cm⁻² eV⁻¹ for TiO₂ and from ~ 1.8 × 10¹² to ~ 7 × 10¹¹ cm⁻² eV⁻¹ for NiTiO₃. Leakage current at 2.5 MV cm⁻¹ was reduced from ~ 2 × 10⁻⁵ to ~ 4 × 10⁻⁶ A cm⁻² in TiO₂ films. Bias-stress tests showed less than 15% current drift in tuned devices. Weibull analysis indicated an increased shape parameter and approximately 40% improvement in characteristic lifetime. Optical band gap slightly increased after tuning, confirming reduced defect states. Statistical analysis verified improved reproducibility. The results demonstrate a strong structure–defect–reliability correlation in composition-engineered oxide MOS capacitors.