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 (ZrO 2 ) thin films are attractive as low-cost high-k dielectrics for thin-film transistors and flexible electronics. In this work, ~ 35 nm sol–gel ZrO 2 films were synthesized from zirconium n-propoxide via multi-layer spin coating on Si and annealed at 400–600 °C in either 100% O 2 or 25% O 2 / 75% N 2 atmospheres. Comprehensive electrical characterization revealed that pure O 2 annealing suppressed oxygen vacancies more effectively than 25% O 2 , resulting in significantly reduced leakage current densities (~ 10 − 6 A/cm 2 at + 2.0 V for 600 °C annealing temperature). All samples maintained high dielectric constants above 22, matching dense ZrO 2 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 ZrO 2 gate dielectrics, offering insights on defects for optimizing high-k materials in next-generation electronic devices.