|
1
|
Chan HL, Fields SS, Chen Y, O’Neill TP, Lenox MK, Hubbard WA, Ihlefeld JF, Regan BC. Mapping Ferroelectric Fields Reveals the Origins of the Coercivity Distribution. ACS NANO 2024; 18:20380-20388. [PMID: 39017620 PMCID: PMC11308779 DOI: 10.1021/acsnano.4c04526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Revised: 06/28/2024] [Accepted: 07/01/2024] [Indexed: 07/18/2024]
Abstract
Better techniques for imaging ferroelectric polarization would aid the development of new ferroelectrics and the refinement of old ones. Here we show how scanning transmission electron microscope (STEM) electron beam-induced current (EBIC) imaging reveals ferroelectric polarization with obvious, simply interpretable contrast. Planar imaging of an entire ferroelectric hafnium zirconium oxide (Hf0.5Zr0.5O2, HZO) capacitor shows an EBIC response that is linearly related to the polarization determined in situ with the positive-up, negative-down (PUND) method. The contrast is easily calibrated in MV/cm. The underlying mechanism is magnification-independent, operating equally well on micrometer-sized devices and individual nanoscale domains. Coercive-field mapping reveals that individual domains are biased "positive" and "negative", as opposed to being "easy" and "hard" to switch. The remanent background E-fields generating this bias can be isolated and mapped. Coupled with STEM's native capabilities for structural identification, STEM EBIC imaging provides a revolutionary tool for characterizing ferroelectric materials and devices.
Collapse
Affiliation(s)
- Ho Leung Chan
- Department
of Physics and Astronomy, University of
California, Los Angeles, California 90095, United States
- California
NanoSystems Institute, University of California, Los Angeles, California 90095, United States
| | - Shelby S. Fields
- Department
of Materials Science and Engineering, University
of Virginia, Charlottesville, Virginia 22904, United States
| | - Yueyun Chen
- Department
of Physics and Astronomy, University of
California, Los Angeles, California 90095, United States
- California
NanoSystems Institute, University of California, Los Angeles, California 90095, United States
| | - Tristan P. O’Neill
- Department
of Physics and Astronomy, University of
California, Los Angeles, California 90095, United States
- California
NanoSystems Institute, University of California, Los Angeles, California 90095, United States
| | - Megan K. Lenox
- Department
of Materials Science and Engineering, University
of Virginia, Charlottesville, Virginia 22904, United States
| | - William A. Hubbard
- NanoElectronic
Imaging, Inc., Los Angeles, California 90095, United States
| | - Jon F. Ihlefeld
- Department
of Materials Science and Engineering, University
of Virginia, Charlottesville, Virginia 22904, United States
- Charles
L. Brown Department of Electrical and Computer Engineering, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Brian C. Regan
- Department
of Physics and Astronomy, University of
California, Los Angeles, California 90095, United States
- California
NanoSystems Institute, University of California, Los Angeles, California 90095, United States
- NanoElectronic
Imaging, Inc., Los Angeles, California 90095, United States
| |
Collapse
|
|
2
|
Lu H, Kim DJ, Aramberri H, Holzer M, Buragohain P, Dutta S, Schroeder U, Deshpande V, Íñiguez J, Gruverman A, Dubourdieu C. Electrically induced cancellation and inversion of piezoelectricity in ferroelectric Hf 0.5Zr 0.5O 2. Nat Commun 2024; 15:860. [PMID: 38287021 PMCID: PMC10825184 DOI: 10.1038/s41467-024-44690-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Accepted: 12/30/2023] [Indexed: 01/31/2024] Open
Abstract
HfO2-based thin films hold huge promise for integrated devices as they show full compatibility with semiconductor technologies and robust ferroelectric properties at nanometer scale. While their polarization switching behavior has been widely investigated, their electromechanical response received much less attention so far. Here, we demonstrate that piezoelectricity in Hf0.5Zr0.5O2 ferroelectric capacitors is not an invariable property but, in fact, can be intrinsically changed by electrical field cycling. Hf0.5Zr0.5O2 capacitors subjected to ac cycling undergo a continuous transition from a positive effective piezoelectric coefficient d33 in the pristine state to a fully inverted negative d33 state, while, in parallel, the polarization monotonically increases. Not only can the sign of d33 be uniformly inverted in the whole capacitor volume, but also, with proper ac training, the net effective piezoresponse can be nullified while the polarization is kept fully switchable. Moreover, the local piezoresponse force microscopy signal also gradually goes through the zero value upon ac cycling. Density functional theory calculations suggest that the observed behavior is a result of a structural transformation from a weakly-developed polar orthorhombic phase towards a well-developed polar orthorhombic phase. The calculations also suggest the possible occurrence of a non-piezoelectric ferroelectric Hf0.5Zr0.5O2. Our experimental findings create an unprecedented potential for tuning the electromechanical functionality of ferroelectric HfO2-based devices.
Collapse
Affiliation(s)
- Haidong Lu
- Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, NE, 68588-0299, USA
| | - Dong-Jik Kim
- Helmholtz-Zentrum Berlin für Materialien und Energie, Insitute Functional Oxides for Energy-Efficient Information Technology, Hahn Meitner Platz 1, 14109, Berlin, Germany
| | - Hugo Aramberri
- Materials Research and Technology Department, Luxembourg Institute of Science and Technology (LIST), Avenue des Hauts-Fourneaux 5, L-4362, Esch/Alzette, Luxembourg
| | - Marco Holzer
- Helmholtz-Zentrum Berlin für Materialien und Energie, Insitute Functional Oxides for Energy-Efficient Information Technology, Hahn Meitner Platz 1, 14109, Berlin, Germany
- Freie Universität Berlin, Physical and Theoretical Chemistry, Arnimallee 22, 14195, Berlin, Germany
| | - Pratyush Buragohain
- Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, NE, 68588-0299, USA
| | - Sangita Dutta
- Materials Research and Technology Department, Luxembourg Institute of Science and Technology (LIST), Avenue des Hauts-Fourneaux 5, L-4362, Esch/Alzette, Luxembourg
- Department of Physics and Materials Science, University of Luxembourg, Rue du Brill 41, L-4422, Belvaux, Luxembourg
| | - Uwe Schroeder
- NaMLab gGmbH, Noethnitzer Strasse 64 a, 01187, Dresden, Germany
| | - Veeresh Deshpande
- Helmholtz-Zentrum Berlin für Materialien und Energie, Insitute Functional Oxides for Energy-Efficient Information Technology, Hahn Meitner Platz 1, 14109, Berlin, Germany
| | - Jorge Íñiguez
- Materials Research and Technology Department, Luxembourg Institute of Science and Technology (LIST), Avenue des Hauts-Fourneaux 5, L-4362, Esch/Alzette, Luxembourg.
- Department of Physics and Materials Science, University of Luxembourg, Rue du Brill 41, L-4422, Belvaux, Luxembourg.
| | - Alexei Gruverman
- Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, NE, 68588-0299, USA.
| | - Catherine Dubourdieu
- Helmholtz-Zentrum Berlin für Materialien und Energie, Insitute Functional Oxides for Energy-Efficient Information Technology, Hahn Meitner Platz 1, 14109, Berlin, Germany.
- Freie Universität Berlin, Physical and Theoretical Chemistry, Arnimallee 22, 14195, Berlin, Germany.
| |
Collapse
|
|
3
|
Chouprik A, Negrov D, Tsymbal EY, Zenkevich A. Defects in ferroelectric HfO 2. NANOSCALE 2021; 13:11635-11678. [PMID: 34190282 DOI: 10.1039/d1nr01260f] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The discovery of ferroelectricity in polycrystalline thin films of doped HfO2 has reignited the expectations of developing competitive ferroelectric non-volatile memory devices. To date, it is widely accepted that the performance of HfO2-based ferroelectric devices during their life cycle is critically dependent on the presence of point defects as well as structural phase polymorphism, which mainly originates from defects either. The purpose of this review article is to overview the impact of defects in ferroelectric HfO2 on its functional properties and the resulting performance of memory devices. Starting from the brief summary of defects in classical perovskite ferroelectrics, we then introduce the known types of point defects in dielectric HfO2 thin films. Further, we discuss main analytical techniques used to characterize the concentration and distribution of defects in doped ferroelectric HfO2 thin films as well as at their interfaces with electrodes. The main part of the review is devoted to the recent experimental studies reporting the impact of defects in ferroelectric HfO2 structures on the performance of different memory devices. We end up with the summary and perspectives of HfO2-based ferroelectric competitive non-volatile memory devices.
Collapse
Affiliation(s)
- Anastasia Chouprik
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow region, Russia.
| | | | | | | |
Collapse
|