Roberto Guido, Xuetao Wang, Bohan Xu, Ruben Alcala, Thomas Mikolajick, Uwe Schroeder, Patrick D Lomenzo
{"title":"Ferroelectric Al<sub>0.85</sub>Sc<sub>0.15</sub>N and Hf<sub>0.5</sub>Zr<sub>0.5</sub>O<sub>2</sub> Domain Switching Dynamics.","authors":"Roberto Guido, Xuetao Wang, Bohan Xu, Ruben Alcala, Thomas Mikolajick, Uwe Schroeder, Patrick D Lomenzo","doi":"10.1021/acsami.4c05798","DOIUrl":null,"url":null,"abstract":"<p><p>The capability to reliably program partial polarization states with nanosecond programming speed and femtojoule energies per bit in ferroelectrics makes them an ideal candidate to realize multibit memory elements for high-density crossbar arrays, which could enable neural network models with a large number of parameters at the edge. However, a thorough understanding of the domain switching dynamics involved in the polarization reversal is required to achieve full control of the multibit capability. Transient current integration measurements are adopted to investigate the domain dynamics in aluminum scandium nitride (Al<sub>0.85</sub>Sc<sub>0.15</sub>N) and hafnium zirconium oxide (Hf<sub>0.5</sub>Zr<sub>0.5</sub>O<sub>2</sub>). The switching dynamics are correlated to the crystal structure of the films. The contributions of domain nucleation and domain wall motion are decoupled by analyzing the rate of change of the time-dependent normalized switched polarization. Thermally activated creep domain wall motion characterizes the Al<sub>0.85</sub>Sc<sub>0.15</sub>N switching dynamics. The statistics of independently nucleating domains and the domain wall creep motion in Hf<sub>0.5</sub>Zr<sub>0.5</sub>O<sub>2</sub> are associated with the spatially inhomogeneous distribution of local switching field due to polymorphism, absence of preferential crystallite orientation, as well as defects and charges that can be located at the grain boundaries. The <i>c</i>-axis texture, single-phase nature, and strong likelihood of less fabrication process-induced defects contribute to the homogeneity of the local switching field in Al<sub>0.85</sub>Sc<sub>0.15</sub>N. Nonetheless, defects generated and redistributed upon bipolar electric field switching cycling result in Al<sub>0.85</sub>Sc<sub>0.15</sub>N domain wall pinning. The wake-up effect in Hf<sub>0.5</sub>Zr<sub>0.5</sub>O<sub>2</sub> is explained thorough the continuous addition of switchable regions associated with two independent distributions of characteristic switching times.</p>","PeriodicalId":5,"journal":{"name":"ACS Applied Materials & Interfaces","volume":null,"pages":null},"PeriodicalIF":8.3000,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"ACS Applied Materials & Interfaces","FirstCategoryId":"88","ListUrlMain":"https://doi.org/10.1021/acsami.4c05798","RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2024/7/31 0:00:00","PubModel":"Epub","JCR":"Q1","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
The capability to reliably program partial polarization states with nanosecond programming speed and femtojoule energies per bit in ferroelectrics makes them an ideal candidate to realize multibit memory elements for high-density crossbar arrays, which could enable neural network models with a large number of parameters at the edge. However, a thorough understanding of the domain switching dynamics involved in the polarization reversal is required to achieve full control of the multibit capability. Transient current integration measurements are adopted to investigate the domain dynamics in aluminum scandium nitride (Al0.85Sc0.15N) and hafnium zirconium oxide (Hf0.5Zr0.5O2). The switching dynamics are correlated to the crystal structure of the films. The contributions of domain nucleation and domain wall motion are decoupled by analyzing the rate of change of the time-dependent normalized switched polarization. Thermally activated creep domain wall motion characterizes the Al0.85Sc0.15N switching dynamics. The statistics of independently nucleating domains and the domain wall creep motion in Hf0.5Zr0.5O2 are associated with the spatially inhomogeneous distribution of local switching field due to polymorphism, absence of preferential crystallite orientation, as well as defects and charges that can be located at the grain boundaries. The c-axis texture, single-phase nature, and strong likelihood of less fabrication process-induced defects contribute to the homogeneity of the local switching field in Al0.85Sc0.15N. Nonetheless, defects generated and redistributed upon bipolar electric field switching cycling result in Al0.85Sc0.15N domain wall pinning. The wake-up effect in Hf0.5Zr0.5O2 is explained thorough the continuous addition of switchable regions associated with two independent distributions of characteristic switching times.
期刊介绍:
ACS Applied Materials & Interfaces is a leading interdisciplinary journal that brings together chemists, engineers, physicists, and biologists to explore the development and utilization of newly-discovered materials and interfacial processes for specific applications. Our journal has experienced remarkable growth since its establishment in 2009, both in terms of the number of articles published and the impact of the research showcased. We are proud to foster a truly global community, with the majority of published articles originating from outside the United States, reflecting the rapid growth of applied research worldwide.