Physical origin of the endurance improvement for HfO2-ZrO2 superlattice ferroelectric film

Abstract

HfO2-ZrO2 superlattice (SL) ferroelectric (FE) ultrathin films exhibit significant improvement in endurance performance compared with solid-solution HfxZr1−xO2 (HZO). Despite the experimental evidence, the underlying microscopic mechanisms of the enhanced reliability of SL remain elusive. This Letter explores the mechanism by performing first-principle calculations on SL and HZO systems. The enhanced endurance in the SL can be well explained by higher oxygen vacancy (Vo) migration energy barriers along the FE polarization direction, which slow down the increase in Vo. The suppression of Vo increase will potentially help maintain the stability of the FE phase and alleviate the fatigue. Based on this mechanism, we suggest that doping materials with higher Vo migration barriers can further improve the endurance of HfO2-based FE devices. This work facilitates the future development of HfO2-based FE devices with enhanced endurance and reliability.