Investigation on the effect of oxygen-rich annealing on electrical and material properties of sol-gel derived zirconium oxide gate dielectric thin films

Solution-processed zirconium oxide (ZrO₂) thin films are attractive as low-cost high-k dielectrics for thin-film transistors and flexible electronics. In this work, ~ 35 nm sol–gel ZrO₂ films were synthesized from zirconium n-propoxide via multi-layer spin coating on Si and annealed at 400–600 °C in either 100% O₂ or 25% O₂ / 75% N₂ atmospheres. Comprehensive electrical characterization revealed that pure O₂ annealing suppressed oxygen vacancies more effectively than 25% O₂, resulting in significantly reduced leakage current densities (~ 10^{− 6} A/cm² at + 2.0 V for 600 °C annealing temperature). All samples maintained high dielectric constants above 22, matching dense ZrO₂ produced by vacuum-based methods. XPS confirmed an increase in Zr–O lattice bonding with temperature, while electrical analysis showed Schottky emission as the dominant leakage mechanism. These findings demonstrate that oxygen-rich annealing provides a simple yet effective route to enhance the reliability of sol-gel derived ZrO₂ gate dielectrics, offering insights on defects for optimizing high-k materials in next-generation electronic devices.