Ferroelectric Tunnel Junction for Dense Cross-Point Arrays

Lee, Hong Sub; Han, Wooje; Chung, Hee Yoon; Rozenberg, M. J.; Kim, Kangsik; Lee, Zonghoon; Yeom, Geun Young; Park, Hyung Ho

doi:10.1021/acsami.5b06117

Cited by 19 publications

(14 citation statements)

References 45 publications

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“…In spin-transfer-torque-magnetic-RAMs (STT-MRAMs), a tunneling barrier is modulated by the parallel/antiparallel magnetization of two ferromagnetic layers, of which one layer can switch its magnetization by spin-polarized currents . In ferroelectric tunnel junctions, the height of a tunneling barrier is modulated by the orientation of the adjacent ferroelectric material, whose remanent polarization can be switched by bipolar voltage pulses . Another class of memristive devices are the redox-based memristive switching devices, which rely on the motion of ionic defects and concurrent redox reactions .…”

Section: Introductionmentioning

confidence: 99%

“…50 In ferroelectric tunnel junctions, the height of a tunneling barrier is modulated by the orientation of the adjacent ferroelectric material, whose remanent polarization can be switched by bipolar voltage pulses. 51 Another class of memristive devices are the redoxbased memristive switching devices, which rely on the motion of ionic defects and concurrent redox reactions. 1 Electrochemical metallization cells (also called conductive bridging random access memories), for example, rely on the electrochemical formation or dissolution of a (typically) Ag or Cu filament within a host insulating layer.…”

Section: ■ Introductionmentioning

confidence: 99%

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Comprehensive Model of Electron Conduction in Oxide-Based Memristive Devices

Funck

Menzel

2021

ACS Appl. Electron. Mater.

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Memristive devices are two-terminal devices that can change their resistance state upon application of appropriate voltage stimuli. The resistance can be tuned over a wide resistance range enabling applications such as multibit data storage or analog computing-in-memory concepts. One of the most promising classes of memristive devices is based on the valence change mechanism in oxide-based devices. In these devices, a configurational change of oxygen defects, i.e. oxygen vacancies, leads to the change of the device resistance. A microscopic understanding of the conduction is necessary in order to design memristive devices with specific resistance properties. In this paper, we discuss the conduction mechanism proposed in the literature and propose a comprehensive, microscopic model of the conduction mechanism in this class of devices. To develop this microscopic picture of the conduction, ab initio simulation models are developed. These simulations suggest two different types of conduction, which are both limited by a tunneling through the Schottky barrier at the metal electrode contact. The difference between the two conduction mechanisms is the following: for the first type, the electrons tunnel into the conduction band and, in the second type, into the vacancy defect states. These two types of conduction differ in their current voltage relation, which has been detected experimentally. The origin of the resistive switching is identical for the two types of conduction and is based on a modification of the tunneling distance due to the oxygen vacancy induced screening of the Schottky barrier. This understanding may help to design optimized devices in terms of the dynamic resistance range for specific applications.

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Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Comprehensive Model of Electron Conduction in Oxide-Based Memristive Devices

Funck

Menzel

2021

ACS Appl. Electron. Mater.

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“…The concept of the ferroelectric tunnel junction (FTJ) was first developed by Tsymbal and Zhuravleve. 202,203 Besides oxide-based FTJ, 204,205 a large number of materials have already been utilized in the FTJ and FTJ-based devices, such as transition metal dichalcogenides 206 and organic materials. 207 The readers are recommended to read the reviews 208,209 for more insights and details.…”

Section: Ferroelectric Nmsmmentioning

confidence: 99%

“…A new strategy of a FE-based memory device is considered based on the quantum transport, tunnel current across the ferroelectric interlayer, and its electrode sensitive character. The concept of the ferroelectric tunnel junction (FTJ) was first developed by Tsymbal and Zhuravleve. , Besides oxide-based FTJ, , a large number of materials have already been utilized in the FTJ and FTJ-based devices, such as transition metal dichalcogenides and organic materials . The readers are recommended to read the reviews , for more insights and details.…”

Section: Ferroelectric Nmsmmentioning

confidence: 99%

Nonvolatile Multistates Memories for High-Density Data Storage

Cao

Lü

Wang

et al. 2020

ACS Appl. Mater. Interfaces

116

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In the current information age, the realization of memory devices with energy efficient design, high storage density, nonvolatility, fast access, and low cost is still a great challenge. As a promising technology to meet these stringent requirements, nonvolatile multistates memory (NMSM) has attracted lots of attention over the past years. Owing to the capability to store data in more than a single bit (0 or 1), the storage density is dramatically enhanced without scaling down the memory cell, making memory devices more efficient and less expensive. Multistates in a single cell also provide an unconventional in-memory computing platform beyond the Von Neumann architecture and enable neuromorphic computing with low power consumption. In this review, an in-depth perspective is presented on the recent progress and challenges on the device architectures, material innovation, working mechanisms of various types of NMSMs, including flash, magnetic random-access memory (MRAM), resistive random-access memory (RRAM), ferroelectric random-access memory (FeRAM), and phase-change memory (PCM). The intriguing properties and performance of these NMSMs, which are the key to realizing highly integrated memory hierarchy, are discussed and compared.

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“…This tunneling conductance, or tunneling electroresistance (TER), can be gradually switched by the partial domain switching of polycrystalline ferroelectrics. , Hafnia-based FTJs have the advantages of simple fabrication, low-power operation, fast switching, and nondestructive readout. In addition, the FTJ-based crossbar array architecture is an efficient method for increasing the integration density (4F 2 ) to overcome the fundamental scaling limits of conventional three-terminal memory arrays. , However, during read and write operations, the unselected cells that shared the word and bit lines with the selected cell were reversely biased, which may cause the flow of the “sneak-path current”. Therefore, crossbar arrays suffer from serious read failure because of the leakage current through the sneak current path, particularly when the array size is large. − …”

Section: Introductionmentioning

confidence: 99%

Selector-less Ferroelectric Tunnel Junctions by Stress Engineering and an Imprinting Effect for High-Density Cross-Point Synapse Arrays

Goh

Hwang

Kim

et al. 2021

ACS Appl. Mater. Interfaces

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In the quest for highly scalable and three-dimensional (3D) stackable memory components, ferroelectric tunnel junction (FTJ) crossbar architectures are promising technologies for nonvolatile logic and neuromorphic computing. Most FTJs, however, require additional nonlinear devices to suppress sneakpath current, limiting large-scale arrays in practical applications. Moreover, the giant tunneling electroresistance (TER) remains challenging due to their inherent weak polarization. Here, we present that the employment of a diffusion barrier layer as well as a bottom metal electrode having a significantly low thermal expansion coefficient has been identified as an important way to enhance the strain, stabilize the ferroelectricity, and manage the leakage current in ultrathin hafnia film, achieving a high TER of 100, negligible resistance changes even up to 10 8 cycles, and a high switching speed of a few tens of nanoseconds. Also, we demonstrate that the usage of an imprinting effect in a ferroelectric capacitor induced by an ionized oxygen vacancy near the electrode results in highly asymmetric current−voltage characteristics with a rectifying ratio of 1000. Notably, the proposed FTJ exhibits a high density array size (>4k) with a securing read margin of 10%. These findings provide a guideline for the design of high-performance and selector-free FTJ devices for large-scale crossbar arrays in neuromorphic applications.

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Ferroelectric Tunnel Junction for Dense Cross-Point Arrays

Cited by 19 publications

References 45 publications

Comprehensive Model of Electron Conduction in Oxide-Based Memristive Devices

Comprehensive Model of Electron Conduction in Oxide-Based Memristive Devices

Nonvolatile Multistates Memories for High-Density Data Storage

Selector-less Ferroelectric Tunnel Junctions by Stress Engineering and an Imprinting Effect for High-Density Cross-Point Synapse Arrays

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