We recently completed a beamtime campaign at the UE49-PGM SPEEM beamline of BESSY II synchrotron in Berlin. The beamline is equipped with a photo-electron emission microscope (PEEM) devoted to element-selective and magnetic-sensitive space resolved investigations. In this beamtime, we exploited the facility’s capabilities of full polarization control of the incoming beam –delivering light of linear vertical or linear horizontal polarization– to perform X-ray Linear Dichroism (XLD) measurements on ferroelectric hafnium zirconium oxide devices. The x-ray absorption (XAS)-PEEM mode of the setup images the secondary electron emission at fixed kinetic energy, while the photon energy hν is scanned. The resulting spectra carry information on the local structure of the atoms and their shape can be related to the crystalline phase composition of HZO. XLD takes then advantage of the anisotropic absorption of linearly polarized X-ray radiation and provides an insight on the extent of polar distortion present in the ferroelectric layer in each direction (in-plane or out-of-plane).

The objective of this beamtime was to investigate the evolution of this polar distortion to corroborate the presence of a ferroelastic switch in HZO-based ferroelectric capacitors with different film thicknesses upon wake up. These experiments contribute to a broader effort to understand and engineer ferroelectric materials for next-generation memory devices.