Short-Range Order in Amorphous and Crystalline Ferroelectric Hf0.5Zr0.5O2

Resumo

The microstructures of amorphous and polycrystalline ferroelectric Hf_0.5Zr_0.5O₂ films are studied by X-ray spectroscopy and ellipsometry. EXAFS spectra demonstrate that the amorphous film consists of an “incompletely mixed” solid solution of metallic oxides HfO₂ and ZrO₂. After rapid thermal annealing, the mixed Hf_0.5Zr_0.5O₂ oxide films have a more ordered polycrystalline structure, and individual Hf and Zr monoxide islands are formed in the films. These islands are several nanometers in size and have a structure that is similar to the monoclinic structure of HfO₂ and ZrO₂. The presence of the HfO₂ and ZrO₂ phases in the Hf_0.5Zr_0.5O₂ films is also detected by ellipsometry.