Antiferroelectric properties of ZrO2 ultra-thin films prepared by atomic layer deposition

Abstract

Antiferroelectric (AFE) properties of ultrathin ZrO2 films prepared by atomic layer deposition are systematically investigated with different film thicknesses and postmetallization annealing (PMA) temperatures. After wake-up, excellent AFE characteristics are observed for the ZrO2 thickness from 5.3 to 9.5 nm through the polarization-electric field and switching current-electric field measurements. The thickness dependence and PMA temperature dependence of AFE properties and their relations to the crystalline phase are discussed. The best AFE properties, such as the largest maximum polarization and a relatively small remanent polarization, are obtained in 6 nm-thick ZrO2 with 400 °C PMA, attributed to the existence of the highest ratio of a tetragonal phase in the film. AFE properties are relatively degraded in other thicknesses of ZrO2 films with 400 °C PMA, which is attributable to the existence of large amounts of an amorphous phase and a monoclinic phase in 5.3 and 9.5 nm-thick ZrO2 films, respectively. Furthermore, it is found that higher PMA temperature of 600 °C can lead to a relatively larger remanent polarization for AFE ZrO2 due to the increase in the ratio of the orthorhombic phase in ZrO2 films.