Breakdown and polarization contrasts in ferroelectric devices observed by operando laser-based photoemission electron microscopy with the AC/DC electrical characterization system

TL;DR

This paper introduces an operando laser-PEEM system combined with electrical characterization to visualize polarization, conduction filaments, and electronic states in ferroelectric devices during operation.

Contribution

The study develops a novel laser-PEEM method integrated with a ferroelectric characterization system for real-time imaging of ferroelectric device phenomena.

Findings

Successfully visualized polarization hysteresis loops in HZO capacitors.

Observed conduction filaments post dielectric breakdown without destructive processing.

Visualized polarization contrast in oxide semiconductor top electrodes.

Abstract

We have developed an operando laser-based photoemission electron microscope (laser-PEEM) with a ferroelectric characterization system. A Sawyer-Tower circuit was implemented to measure the polarization-voltage ($P-V$) characteristics of ferroelectric devices. Using this system, we successfully obtained the well-defined $P-V$ hysteresis loops for a ferroelectric capacitor incorporating Hf$_{0.5}$Zr$_{0.5}$O$_2$ (HZO), reproducing the typical field-cycling characteristics of HZO capacitors. After dielectric breakdown caused by field-cycling stress, we visualized a conduction filament through the top electrode without any destructive processing. Additionally, we successfully observed polarization contrast through the top electrode of an oxide semiconductor (InZnO$_x$). These results indicate that our operando laser-PEEM system is a powerful tool for visualizing conduction filaments after dielectric breakdown, the ferroelectric polarization contrasts, and electronic state distribution of materials implemented in ferroelectric devices, including ferroelectric field-effect transistors and ferroelectric tunnel junctions.