Influence of Biaxial Strain and Interfacial Layer Growth on Ferroelectric Wake-Up and Phase Transition Fields in ZrO.

Investigations on fluorite-structured ferroelectric HfO/ZrO thin films are aiming to achieve high-performance films required for memory and computing technologies. These films exhibit excellent scalability and compatibility with the complementary metal-oxide semiconductor process used by semiconductor foundries, but stabilizing ferroelectric properties with a low operation voltage in the as-fabricated state of these films is a critical component for technology advancement. After removing the influence of interfacial layers, a linear correlation is observed between the biaxial strain and the electric field for transforming the nonferroelectric tetragonal to the ferroelectric orthorhombic phase in ZrO thin films. This observation is supported by applying the principle of energy conservation in combination with ab initio and molecular dynamics simulations. According to the simulations, a rarely reported orthorhombic phase may be stabilized by tuning biaxial strain in the ZrO films. This study demonstrates the significant influence of interfacial layers and biaxial strain on the phase transition fields and shows how strain engineering can be used to improve ferroelectric wake-up in ZrO.