Evolution of phases and ferroelectric properties of thin Hf0.5Zr0.5O2 films according to the thickness and annealing temperature

Abstract

The effects of annealing temperature (T_anneal) and film thickness (t_f) on the crystal structure and ferroelectric properties of Hf_0.5Zr_0.5O₂ films were examined. The Hf_0.5Zr_0.5O₂ films consist of tetragonal, orthorhombic, and monoclinic phases. The orthorhombic phase content, which is responsible for the ferroelectricity in this material, is almost independent of T_anneal, but decreases with increasing t_f. In contrast, increasing T_anneal and t_f monotonically increases (decreases) the amount of monoclinic (tetragonal) phase, which coincides with the variations in the dielectric constant. The remanant polarization was determined by the content of orthorhombic phase as well as the spatial distribution of other phases.