Temperature-dependent microstructure, ferroelectric, and energy storage performance of sol-gel Hf0.5Zr0.5O2 thin films

In recent years, hafnium–zirconium oxide systems have drawn intensive attention as energy storage capacitors owing to their excellent electrical properties and complementary metal–oxide–semiconductor compatibility. In this work, we fabricated Hf0.5Zr0.5O2 thin films on p-type silicon substrates using a sol-gel method. Through investigating the influence of annealing temperature on the phase structure and energy storage performance, it is found that the structural evolution from orthorhombic/tetragonal phase to the predominant monoclinic phase driven by increasing the annealing temperature will correspondingly induce state-phase transition from ferroelectric to linear-like dielectric accompanied by an enhanced breakdown strength (∼7.94 MV/cm), a large energy density (∼54.8 J/cm3), and a high efficiency (∼81.6%) for Hf0.5Zr0.5O2 thin films annealed at 850 °C. Meanwhile, a good thermal stability (20–200 °C) and superior fatigue endurance (106 cycles) have also been achieved, revealing that regulating the monoclinic-phase fraction in the orthorhombic/tetragonal matrix is effective in improving the energy storage properties.