Impact of Hafnium Doping on Phase Transition, Interface, and Reliability Properties of Zr_xHf_1–xO₂-Based Capacitors

Zirconium oxide and zirconium-rich Zr_xHf_1–xO₂ thin films have attracted attention owing to their switching stability and significant promise for commercial applications such as high-performance, nonvolatile memory devices, high-density energy storage devices, and supercapacitors. In the path toward commercial applications, understanding the factors influencing the formation of ferroelectric properties in these films is essential. This study explores the impact of hafnium doping on various factors affecting the formation of the ferroelectric phase in zirconium-rich hafnium oxide thin films. This work highlights that hafnium doping in zirconium oxide monotonically lowers the energy barrier for the antiferroelectric to ferroelectric phase transition. At the same time, it reduces the thickness of the parasitic layers formed at the metal nitride electrode-dielectric interfaces. Furthermore, it is demonstrated that the hafnium doping decreases the leakage current density, thus providing insights into lowering the defect density in zirconium-rich hafnium oxide films.