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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.
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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.
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2
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Ghasemian MB, Zavabeti A, Allioux FM, Sharma P, Mousavi M, Rahim MA, Khayyam Nekouei R, Tang J, Christofferson AJ, Meftahi N, Rafiezadeh S, Cheong S, Koshy P, Tilley RD, McConville CF, Russo SP, Ton-That C, Seidel J, Kalantar-Zadeh K. Liquid Metal Doping Induced Asymmetry in Two-Dimensional Metal Oxides. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2309924. [PMID: 38263808 DOI: 10.1002/smll.202309924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 01/09/2024] [Indexed: 01/25/2024]
Abstract
The emergence of ferroelectricity in two-dimensional (2D) metal oxides is a topic of significant technological interest; however, many 2D metal oxides lack intrinsic ferroelectric properties. Therefore, introducing asymmetry provides access to a broader range of 2D materials within the ferroelectric family. Here, the generation of asymmetry in 2D SnO by doping the material with Hf0.5 Zr0.5 O2 (HZO) is demonstrated. A liquid metal process as a doping strategy for the preparation of 2D HZO-doped SnO with robust ferroelectric characteristics is implemented. This technology takes advantage of the selective interface enrichment of molten Sn with HZO crystallites. Molecular dynamics simulations indicate a strong tendency of Hf and Zr atoms to migrate toward the surface of liquid metal and embed themselves within the growing oxide layer in the form of HZO. Thus, the liquid metal-based harvesting/doping technique is a feasible approach devised for producing novel 2D metal oxides with induced ferroelectric properties, represents a significant development for the prospects of random-access memories.
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Affiliation(s)
- Mohammad B Ghasemian
- School of Chemical and Biomolecular Engineering, University of Sydney, Sydney, NSW, 2006, Australia
- School of Chemical Engineering, University of New South Wales (UNSW), Sydney, NSW, 2052, Australia
| | - Ali Zavabeti
- Department of Chemical Engineering, The University of Melbourne, Parkville, VIC, 3010, Australia
- School of Science, RMIT University, Melbourne, VIC, 3000, Australia
| | - Francois-Marie Allioux
- School of Chemical and Biomolecular Engineering, University of Sydney, Sydney, NSW, 2006, Australia
- School of Chemical Engineering, University of New South Wales (UNSW), Sydney, NSW, 2052, Australia
| | - Pankaj Sharma
- ARC Center of Excellence in Future Low-Energy Electronics Technologies (FLEET), University of New South Wales (UNSW), Sydney, NSW, 2052, Australia
- College of Science and Engineering, Flinders University, Bedford Park, Adelaide, SA, 5042, Australia
- Flinders Institute for Nanoscale Science and Technology, Flinders University, Adelaide, SA, 5042, Australia
| | - Maedehsadat Mousavi
- School of Chemical Engineering, University of New South Wales (UNSW), Sydney, NSW, 2052, Australia
| | - Md Arifur Rahim
- School of Chemical and Biomolecular Engineering, University of Sydney, Sydney, NSW, 2006, Australia
- School of Chemical Engineering, University of New South Wales (UNSW), Sydney, NSW, 2052, Australia
| | - Rasoul Khayyam Nekouei
- School of Materials Science and Engineering, University of New South Wales (UNSW), Sydney, NSW, 2052, Australia
| | - Jianbo Tang
- School of Chemical Engineering, University of New South Wales (UNSW), Sydney, NSW, 2052, Australia
| | - Andrew J Christofferson
- School of Science, RMIT University, Melbourne, VIC, 3000, Australia
- ARC Center of Excellence in Exciton Science, School of Science, RMIT University, Melbourne, Victoria, 3000, Australia
| | - Nastaran Meftahi
- ARC Center of Excellence in Exciton Science, School of Science, RMIT University, Melbourne, Victoria, 3000, Australia
| | - Somayeh Rafiezadeh
- School of Mathematical and Physical Sciences, University of Technology Sydney, Ultimo, NSW, 2007, Australia
| | - Soshan Cheong
- Mark Wainwright Analytical Centre, Electron Microscope Unit, University of New South Wales (UNSW), Sydney, NSW, 2052, Australia
| | - Pramod Koshy
- School of Materials Science and Engineering, University of New South Wales (UNSW), Sydney, NSW, 2052, Australia
| | - Richard D Tilley
- Mark Wainwright Analytical Centre, Electron Microscope Unit, University of New South Wales (UNSW), Sydney, NSW, 2052, Australia
- School of Chemistry and Australian Centre for NanoMedicine, University of New South Wales (UNSW), Sydney, NSW, 2052, Australia
| | - Chris F McConville
- School of Science, RMIT University, Melbourne, VIC, 3000, Australia
- Institute for Frontier Materials, Deakin University, Geelong, Victoria, 3216, Australia
| | - Salvy P Russo
- ARC Center of Excellence in Exciton Science, School of Science, RMIT University, Melbourne, Victoria, 3000, Australia
| | - Cuong Ton-That
- School of Mathematical and Physical Sciences, University of Technology Sydney, Ultimo, NSW, 2007, Australia
| | - Jan Seidel
- ARC Center of Excellence in Future Low-Energy Electronics Technologies (FLEET), University of New South Wales (UNSW), Sydney, NSW, 2052, Australia
- School of Materials Science and Engineering, University of New South Wales (UNSW), Sydney, NSW, 2052, Australia
| | - Kourosh Kalantar-Zadeh
- School of Chemical and Biomolecular Engineering, University of Sydney, Sydney, NSW, 2006, Australia
- School of Chemical Engineering, University of New South Wales (UNSW), Sydney, NSW, 2052, Australia
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3
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Guberna E, Margolin I, Kalika E, Zarubin S, Zhuk M, Chouprik A. Giant Electromechanical Effect in Piezoelectric Nanomembranes Based on Hf 0.5Zr 0.5O 2. ACS APPLIED MATERIALS & INTERFACES 2024; 16:975-984. [PMID: 38112334 DOI: 10.1021/acsami.3c11141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
Since ultrathin ferroelectric HfO2 films can be conformally grown by atomic layer deposition even on complex three-dimensional structures, new horizons in the development of next-generation piezoelectric devices are opened. However, hafnium oxide has a significant drawback for piezoelectric applications: its piezoelectric coefficients are much smaller than those of classical materials currently used in piezoelectric devices. Therefore, new approaches to the development of high-performance piezoelectric devices based on exploiting the unique properties of HfO2 are of paramount importance. In this work, a giant electromechanical effect in miniature piezoelectric membrane devices based on a 10 nm-thick ferroelectric Hf0.5Zr0.5O2 (HZO) film is experimentally demonstrated. Compared to the pure piezoelectric effect in the HZO film, the gain of the electromechanical response in membrane devices reaches 25 times. Numerical simulations confirm that this effect stems from the asymmetric shape of the membranes and can be further improved by designing the device geometry. Furthermore, according to first-principles calculations, an additional opportunity to improve the piezoelectric coefficient, and hence, the device efficiency is provided by the engineering of the mechanical stress in the HZO film. The proposed approach enables the development of new promising piezoelectric devices including miniature reflectors, nanoactuators, and nanoswitches.
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Affiliation(s)
- Elizaveta Guberna
- Moscow Institute of Physics and Technology, Dolgoprudny 141701, Russia
| | - Ilya Margolin
- Moscow Institute of Physics and Technology, Dolgoprudny 141701, Russia
| | - Elizaveta Kalika
- Moscow Institute of Physics and Technology, Dolgoprudny 141701, Russia
| | - Sergei Zarubin
- Moscow Institute of Physics and Technology, Dolgoprudny 141701, Russia
| | - Maksim Zhuk
- Moscow Institute of Physics and Technology, Dolgoprudny 141701, Russia
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4
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Buragohain P, Lu H, Richter C, Schenk T, Kariuki P, Glinsek S, Funakubo H, Íñiguez J, Defay E, Schroeder U, Gruverman A. Quantification of the Electromechanical Measurements by Piezoresponse Force Microscopy. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2206237. [PMID: 36210741 DOI: 10.1002/adma.202206237] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Revised: 09/10/2022] [Indexed: 06/16/2023]
Abstract
Piezoresponse force microscopy (PFM) is widely used for characterization and exploration of the nanoscale properties of ferroelectrics. However, quantification of the PFM signal is challenging due to the convolution of various extrinsic and intrinsic contributions. Although quantification of the PFM amplitude signal has received considerable attention, quantification of the PFM phase signal has not been addressed. A properly calibrated PFM phase signal can provide valuable information on the sign of the local piezoelectric coefficient-an important and nontrivial issue for emerging ferroelectrics. In this work, two complementary methodologies to calibrate the PFM phase signal are discussed. The first approach is based on using a standard reference sample with well-known independently measured piezoelectric coefficients, while the second approach exploits the electrostatic sample-cantilever interactions to determine the parasitic phase offset. Application of these methodologies to studies of the piezoelectric behavior in ferroelectric HfO2 -based thin-film capacitors reveals intriguing variations in the sign of the longitudinal piezoelectric coefficient, d33,eff . It is shown that the piezoelectric properties of the HfO2 -based capacitors are inherently sensitive to their thickness, electrodes, as well as deposition methods, and can exhibit wide variations including a d33,eff sign change within a single device.
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Affiliation(s)
- Pratyush Buragohain
- Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Haidong Lu
- Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Claudia Richter
- NaMLab gGmbH, 01187, Noethnitzer Strasse 64 a, Dresden, Germany
| | - Tony Schenk
- Ferroelectric Memory GmbH, 01099, Charlotte-Bühler-Str. 12, Dresden, Germany
| | - Pamenas Kariuki
- NaMLab gGmbH, 01187, Noethnitzer Strasse 64 a, Dresden, Germany
| | - Sebastjan Glinsek
- Materials Research and Technology Department, Luxembourg Institute of Science and Technology, 41 Rue du Brill, Belvaux, L-4422, Luxembourg
| | - Hiroshi Funakubo
- School of Materials and Chemical Technology, Tokyo Institute of Technology, Yokohama, 226-8502, Japan
| | - Jorge Íñiguez
- Materials Research and Technology Department, Luxembourg Institute of Science and Technology, 41 Rue du Brill, Belvaux, L-4422, Luxembourg
- Department of Physics and Materials Science, University of Luxembourg, 41 Rue du Brill, Belvaux, L-4422, Luxembourg
| | - Emmanuel Defay
- Materials Research and Technology Department, Luxembourg Institute of Science and Technology, 41 Rue du Brill, Belvaux, L-4422, Luxembourg
| | - Uwe Schroeder
- NaMLab gGmbH, 01187, Noethnitzer Strasse 64 a, Dresden, Germany
| | - Alexei Gruverman
- Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
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5
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Killgore JP, Robins L, Collins L. Electrostatically-blind quantitative piezoresponse force microscopy free of distributed-force artifacts. NANOSCALE ADVANCES 2022; 4:2036-2045. [PMID: 36133417 PMCID: PMC9418616 DOI: 10.1039/d2na00046f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 03/15/2022] [Indexed: 06/16/2023]
Abstract
The presence of electrostatic forces and associated artifacts complicates the interpretation of piezoresponse force microscopy (PFM) and electrochemical strain microscopy (ESM). Eliminating these artifacts provides an opportunity for precisely mapping domain wall structures and dynamics, accurately quantifying local piezoelectric coupling coefficients, and reliably investigating hysteretic processes at the single nanometer scale to determine properties and mechanisms which underly important applications including computing, batteries and biology. Here we exploit the existence of an electrostatic blind spot (ESBS) along the length of the cantilever, due to the distributed nature of the electrostatic force, which can be universally used to separate unwanted long range electrostatic contributions from short range electromechanical responses of interest. The results of ESBS-PFM are compared to state-of-the-art interferometric displacement sensing PFM, showing excellent agreement above their respective noise floors. Ultimately, ESBS-PFM allows for absolute quantification of piezoelectric coupling coefficients independent of probe, lab or experimental conditions. As such, we expect the widespread adoption of EBSB-PFM to be a paradigm shift in the quantification of nanoscale electromechanics.
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Affiliation(s)
- Jason P Killgore
- Applied Chemicals and Materials Division, National Institute of Standards and Technology Boulder CO USA
| | - Larry Robins
- Applied Chemicals and Materials Division, National Institute of Standards and Technology Boulder CO USA
| | - Liam Collins
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory Oak Ridge TN USA
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6
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Lee K, Park K, Lee HJ, Song MS, Lee KC, Namkung J, Lee JH, Park J, Chae SC. Enhanced ferroelectric switching speed of Si-doped HfO 2 thin film tailored by oxygen deficiency. Sci Rep 2021; 11:6290. [PMID: 33737670 PMCID: PMC7973512 DOI: 10.1038/s41598-021-85773-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 02/22/2021] [Indexed: 12/01/2022] Open
Abstract
Investigations concerning oxygen deficiency will increase our understanding of those factors that govern the overall material properties. Various studies have examined the relationship between oxygen deficiency and the phase transformation from a nonpolar phase to a polar phase in HfO2 thin films. However, there are few reports on the effects of oxygen deficiencies on the switching dynamics of the ferroelectric phase itself. Herein, we report the oxygen- deficiency induced enhancement of ferroelectric switching properties of Si-doped HfO2 thin films. By controlling the annealing conditions, we controlled the oxygen deficiency concentration in the ferroelectric orthorhombic HfO2 phase. Rapid high-temperature (800 °C) annealing of the HfO2 film accelerated the characteristic switching speed compared to low-temperature (600 °C) annealing. Scanning transmission electron microscopy and electron energy-loss spectroscopy (EELS) revealed that thermal annealing increased oxygen deficiencies, and first-principles calculations demonstrated a reduction of the energy barrier of the polarization flip with increased oxygen deficiency. A Monte Carlo simulation for the variation in the energy barrier of the polarization flipping confirmed the increase of characteristic switching speed.
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Affiliation(s)
- Kyoungjun Lee
- Department of Physics Education, Seoul National University, Seoul, 08826, Korea
| | - Kunwoo Park
- School of Chemical and Biological Engineering, Institute of Chemical Process, Seoul National University, Seoul, 08826, Korea.,Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul, 08826, Korea
| | - Hyun-Jae Lee
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Korea
| | - Myeong Seop Song
- Department of Physics Education, Seoul National University, Seoul, 08826, Korea
| | - Kyu Cheol Lee
- Department of Physics Education, Seoul National University, Seoul, 08826, Korea
| | - Jin Namkung
- Department of Physics Education, Seoul National University, Seoul, 08826, Korea
| | - Jun Hee Lee
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Korea
| | - Jungwon Park
- School of Chemical and Biological Engineering, Institute of Chemical Process, Seoul National University, Seoul, 08826, Korea.,Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul, 08826, Korea
| | - Seung Chul Chae
- Department of Physics Education, Seoul National University, Seoul, 08826, Korea.
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7
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Mahmood A, Echtenkamp W, Street M, Wang JL, Cao S, Komesu T, Dowben PA, Buragohain P, Lu H, Gruverman A, Parthasarathy A, Rakheja S, Binek C. Voltage controlled Néel vector rotation in zero magnetic field. Nat Commun 2021; 12:1674. [PMID: 33723249 PMCID: PMC7960997 DOI: 10.1038/s41467-021-21872-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 02/11/2021] [Indexed: 11/16/2022] Open
Abstract
Multi-functional thin films of boron (B) doped Cr2O3 exhibit voltage-controlled and nonvolatile Néel vector reorientation in the absence of an applied magnetic field, H. Toggling of antiferromagnetic states is demonstrated in prototype device structures at CMOS compatible temperatures between 300 and 400 K. The boundary magnetization associated with the Néel vector orientation serves as state variable which is read via magnetoresistive detection in a Pt Hall bar adjacent to the B:Cr2O3 film. Switching of the Hall voltage between zero and non-zero values implies Néel vector rotation by 90 degrees. Combined magnetometry, spin resolved inverse photoemission, electric transport and scanning probe microscopy measurements reveal B-dependent TN and resistivity enhancement, spin-canting, anisotropy reduction, dynamic polarization hysteresis and gate voltage dependent orientation of boundary magnetization. The combined effect enables H = 0, voltage controlled, nonvolatile Néel vector rotation at high-temperature. Theoretical modeling estimates switching speeds of about 100 ps making B:Cr2O3 a promising multifunctional single-phase material for energy efficient nonvolatile CMOS compatible memory applications.
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Affiliation(s)
- Ather Mahmood
- Department of Physics & Astronomy and the Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Will Echtenkamp
- Department of Physics & Astronomy and the Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Mike Street
- Department of Physics & Astronomy and the Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Jun-Lei Wang
- Department of Physics & Astronomy and the Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Shi Cao
- Department of Physics & Astronomy and the Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Takashi Komesu
- Department of Physics & Astronomy and the Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Peter A Dowben
- Department of Physics & Astronomy and the Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Pratyush Buragohain
- Department of Physics & Astronomy and the Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Haidong Lu
- Department of Physics & Astronomy and the Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Alexei Gruverman
- Department of Physics & Astronomy and the Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Arun Parthasarathy
- Department of Electrical Engineering, New York University, Brooklyn, NY, USA
| | - Shaloo Rakheja
- Holonyak Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Christian Binek
- Department of Physics & Astronomy and the Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE, USA.
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8
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Collins L, Celano U. Revealing Antiferroelectric Switching and Ferroelectric Wakeup in Hafnia by Advanced Piezoresponse Force Microscopy. ACS APPLIED MATERIALS & INTERFACES 2020; 12:41659-41665. [PMID: 32870659 DOI: 10.1021/acsami.0c07809] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Hafnium oxide (HfO2)-based ferroelectrics offer remarkable promise for memory and logic devices in view of their compatibility with traditional silicon complementary metal oxide semiconductor (CMOS) technology, high switchable polarization, good endurance, and thickness scalability. These factors have led to a steep rise in the level of research on HfO2 over the past number of years. While measurements on capacitors are promising for understanding macroscopic effects, many open questions regarding the emergence of ferroelectricity and electric field cycling behaviors remain. Continued progress requires information regarding the nanoscale ferroelectric behaviors on the bare surface (i.e., without encapsulation), which is notably absent. To overcome this barrier, we have applied complementary modes of piezoresponse force microscopy with the goal of directly and quantitatively sensing nanoscale ferroelectric behaviors in bare HfO2 thin films. Our results on 8 nm Si-doped HfO2 reveal nanoscale domains of local remnant polarization states exhibiting a weak piezoelectric coupling (deff) in the range 0.6-1.5 pm/V. While we observed localized enhancement of deff during progressive stressing of the bare HfO2 thin film, we did not detect stable polarization switching which is a prerequisite of ferroelectric switching. This result could be explained using polarization switching spectroscopy which revealed antiferroelectric-like switching in the form of pinched hysteresis loops as well as increasing remnant response with repeated cycling. As such, our results offer a promising route for material scientists who want to explore the nanoscale origins of antiferroelectricity and ferroelectric wakeup in HfO2.
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Affiliation(s)
- Liam Collins
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
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9
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Polarization Switching in 2D Nanoscale Ferroelectrics: Computer Simulation and Experimental Data Analysis. NANOMATERIALS 2020; 10:nano10091841. [PMID: 32942662 PMCID: PMC7559913 DOI: 10.3390/nano10091841] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Revised: 09/10/2020] [Accepted: 09/12/2020] [Indexed: 11/17/2022]
Abstract
The polarization switching kinetics of nanosized ferroelectric crystals and the transition between homogeneous and domain switching in nanoscale ferroelectric films are considered. Homogeneous switching according to the Ginzburg-Landau-Devonshire (LGD) theory is possible only in two-dimensional (2D) ferroelectrics. The main condition for the applicability of the LGD theory in such systems is its homogeneity along the polarization switching direction. A review is given of the experimental results for two-dimensional (2D) films of a ferroelectric polymer, nanosized barium titanate nanofilms, and hafnium oxide-based films. For ultrathin 2D ferroelectric polymer films, the results are confirmed by first-principle calculations. Fitting of the transition region from homogeneous to domain switching by sigmoidal Boltzmann functions was carried out. Boltzmann function fitting data enabled us to correctly estimate the region sizes of the homogeneous switching in which the LGD theory is valid. These sizes contain several lattice constants or monolayers of a nanosized ferroelectrics.
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10
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Mikheev V, Chouprik A, Lebedinskii Y, Zarubin S, Markeev AM, Zenkevich AV, Negrov D. Memristor with a ferroelectric HfO 2 layer: in which case it is a ferroelectric tunnel junction. NANOTECHNOLOGY 2020; 31:215205. [PMID: 32040945 DOI: 10.1088/1361-6528/ab746d] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
New interest in the implementation of ferroelectric tunnel junctions has emerged following the discovery of ferroelectric properties in HfO2 films, which are fully compatible with silicon microelectronics technology. The coercive electric field to switch polarization direction in ferroelectric HfO2 is relatively high compared to classical perovskite materials, and thus it can cause the migration of non-ferroelectric charges in HfO2, namely charged oxygen vacancies. The charge redistribution would cause the change of the tunnel barrier shape and following change of the electroresistance effect. In the case of ambiguous ferroelectric properties of HfO2 ultrathin films, this oxygen-driven resistive switching effect can mimic the tunnel electroresistance effect. Here, we demonstrate two separate resistive switching regimes, depending on the applied voltage, in the same memristor device employing a ferroelectric Hf0.5Zr0.5O2 (4.5 nm) layer. The first regime originates from the polarization reversal, whereas the second one is attributed to the accumulation/depletion of the oxygen vacancies at the electrode interface. The modulation of the tunnel barrier causes the enhancement of R OFF/R ON ratio in ∼20 times compared to the tunnel electroresistance effect. The developed device was used to formulate the criteria for unambiguous discrimination between the ferroelectric-and non-ferroelectric resistive switching effects in HfO2-based ferroelectric tunnel junctions.
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Affiliation(s)
- V Mikheev
- Moscow Institute of Physics and Technology, Dolgoprudny, Russia
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