Probing Polar Distortion in Ferroelectric HZO via XLD-PEEM at BESSY II

Ferro4edgeAI partners recently completed a beamtime campaign at the UE49-PGM SPEEM beamline of the BESSY II synchrotron in Berlin. The beamline is equipped with a photo-electron emission microscope (PEEM) dedicated to element-selective and magnetic-sensitive, spatially resolved investigations.

During this beamtime, partners exploited the facility’s full polarization control of the incoming X-ray beam—delivering linear vertical or linear horizontal polarization—to perform X-ray Linear Dichroism (XLD) measurements on ferroelectric hafnium zirconium oxide (HZO) devices.

The X-ray absorption spectroscopy (XAS)-PEEM mode images secondary electron emission at a fixed kinetic energy while scanning the photon energy hν. The resulting spectra provide information on the local atomic structure, with spectral features that can be directly related to the crystalline phase composition of HZO.

XLD measurements take advantage of the anisotropic absorption of linearly polarized X-ray radiation, enabling insight into the extent of polar distortion within the ferroelectric layer along different directions, both in-plane and out-of-plane.

The primary objective of this beamtime was to investigate the evolution of polar distortion in order to corroborate the presence of ferroelastic switching in HZO-based ferroelectric capacitors with varying film thicknesses during wake-up. These experiments contribute to a broader effort aimed at understanding and engineering ferroelectric materials for next-generation memory devices.