Identification of structural phases in ferroelectric hafnium zirconium oxide by density-functional-theory-assisted EXAFS analysis

Crystalline phase identification for hafnium-based ferroelectrics by diffraction techniques has been elusive. We use density-functional-theory (DFT)-assisted extended X-ray absorption fine-structure spectroscopy (EXAFS) to determine the crystal symmetry of thin hafnium zirconium oxide (Hf0.46Zr0.54O2) films grown atomic layer deposition. Ferroelectric switching in TiN/Hf0.46Zr0.54O2/TiN metal–insulator–metal capacitors is verified. Grazing-incidence fluorescence-yield mode Hf L3 and Zr K edge EXAFS data are compared with reference calculated from DFT-based coordinates various structural phases Hf0.5Zr0.5O2. Via multiphase fitting, we confirm that frequently invoked polar orthorhombic Pca21 present ferroelectric oxide, along an equal amount nonpolar monoclinic P21/c phase. For comparison, verify paraelectric HfO2 exhibit