Enhanced Ferroelectric Performances in Optimized Sol–Gel Y-Doped HfO2 Thin Films

Y-doped HfO2 ferroelectric thin films were fabricated via the sol–gel chemical solution deposition method. The effects of Y doping concentration, film thickness, and annealing temperature on the structure, morphology, and electrical properties were systematically investigated. The results demonstrate that doping concentration, film thickness, and annealing temperature can significantly regulate the crystalline phase composition. Appropriate doping, moderate film thickness, and suitable annealing temperature effectively stabilize the ferroelectric orthorhombic phase and suppress the monoclinic phase. The optimized film is obtained under the conditions of 4 mol% Y doping, a film thickness of 59.2 nm, and rapid thermal annealing at 600 °C, which exhibits the best crystallinity, dense and flat surface, and moderate oxygen vacancy concentration. The optimized sample shows a remnant polarization of 86.9 μC/cm2, a coercive field of 1.1 MV/cm, and a leakage current density as low as 9.77 × 10−6 A/cm2, representing the best ferroelectric performance. This study provides a reliable process and experimental basis for the preparation of high-performance HfO2-based ferroelectric thin films by the sol–gel method.