Minimizing Ferroelectric Imprint via Electrode Design
Yu-Wei Chen1*, Dong-Yuan Yu2, Yun-Chi Su1, Chao-Rung Chen1, Wei-Chen Hung1, Chun-Wei Huang3, Bhagwati Prasad4, Ramamoorthy Ramesh6,5, Yen-Lin Huang1
1Department of Materials Science and Engineering, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
2Taiwan Semiconductor Research Institute, Hsinchu, Taiwan
3Department of Materials Science and Engineering, Feng Chia University, Taichung, Taiwan
4Department of Materials Engineering, Indian Institute of Science, Bangalore, Karnataka, India
5Department of Materials Science and Engineering, Rice University, Texas, USA
6Department of Materials Science and Engineering, University of California, Berkely, USA
* Presenter:Yu-Wei Chen, email:y.w.chen.en11@nycu.edu.tw
Ferroelectric imprint, characterized by an asymmetry in polarization switching, is a critical challenge in low-voltage ferroelectric devices, leading to issues like voltage shifts in P-V hysteresis loops, high operating voltages, and reliability concerns. Despite the use of symmetrical metallic electrodes to reduce imprint, challenges remain, particularly in devices with limited electrode options, such as MagetoEletric Spin-Orbit (MESO) devices. This study explores the use of an asymmetrical electrode design, incorporating a La0.7Sr0.3MnO3 layer in the bottom electrode of a Pt(1)/Co0.9Fe0.1(4)/La0.15Bi0.85FeO3(50)/SrRuO3(30) stack. We demonstrate that this approach effectively reduces the Voffset and achieves more symmetric P-V hysteresis loops. Additionally, an epitaxial ferroelectric capacitor with symmetrical SrRuO3 electrodes was fabricated to investigate the persistent imprint effect. Despite symmetrical electrodes, a Voffset was still observed which we attribute to the difference of work function from the top and bottom SrRuO3 electrodes, underscoring the complexity of fully eliminating imprint. By using the La 0.7Sr0.3MnO3 insertion layer, we finally demonstrate the symmetric P-V hysteresis loops with Voffset = -0.004 V. This work highlights the importance of electrode and interface engineering in addressing ferroelectric imprint and enhancing device.


Keywords: Ferroelectrics, Imprint, BaTiO3, BiFeO3, Reliability