Electron transport across ultrathin ferroelectric Hf0.5Zr0.5O2 films on Si

Chouprik, Anastasia; Chernikova, Anna G.; Markeev, Andrey M.; Mikheev, V. P.; Negrov, Dmitrii; Spiridonov, Maxim; Zarubin, Sergei; Zenkevich, A.

doi:10.1016/j.mee.2017.05.028

Cited by 69 publications

(44 citation statements)

References 8 publications

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“…[50] The following HfO 2 -based FTJs references are considered: epitaxial PLD-deposited MFM-structures [20,30] and MFIM-structures, [31] sputtering-deposited MFM structures, [17,39,60,61] ALD-deposited MFM structures, [62][63][64] MFIM-structures, [18,19,49,[65][66][67][68][69][70] MFS-structures [45,71,72] and MFIS-structures. [43,69,[73][74][75][76][77] Reports of non-polarization-driven resistive switching in HfO 2 -based FTJs are not considered (Supporting Information). b) Comparison of the 1 nm Zr:HfO 2 FTJs in this work to ultrathin (sub-3 nm) HfO 2 -based FTJs and perovskite-based FTJs deposited on Si, considering polarization-driven ON/OFF conductance ratio (J ON /J OFF ) and ON current density (J ON ).…”

Section: Methodsmentioning

confidence: 99%

One Nanometer HfO₂‐Based Ferroelectric Tunnel Junctions on Silicon

Cheema

Shanker

Hsu

et al. 2021

Adv Elect Materials

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incompatibilities with silicon and modern semiconductor processes. [5] Since the discovery of ferroelectricity in HfO 2 -based thin films in 2011, [6] fluorite-structure binary oxides have attracted considerable interest as they are compatible with complementary metal-oxide-semiconductor (CMOS) processes. [7] Accordingly, HfO 2based ferroelectric memory has received significant attention in recent years, [1,8,9] primarily focused on charge-based ferroelectric random access memory (FeRAM) and ferroelectric field effect transistors (FeFETs). [2,10] Meanwhile, resistiveswitching materials-which exhibit electrically-induced resistance changes in metal-dielectric-metal junctions or heterostructures with multi-dielectric barriershave emerged as promising candidates for novel beyond-CMOS data-centric computing paradigms. [11][12][13] In this context, ferroelectric tunnel junctions (FTJs) present a promising energy-efficient resistive switching memory [12,13] as FTJs exploit the ferroic polarization functionality of the insulating barrier. [14] Voltage-controlled polarization-dependent tunneling through the ferroelectric layer (tunnel electroresistance, TER) can yield much larger ON/OFF conductance ratios [15,16] than, for example, current-controlled magnetic tunnel junctions, [12] another two-terminal tunneling resistive switching device.A critical requirement for FTJs is to achieve a sufficiently high tunneling current (J ON ) at the ON state to ensure that a scaled device can be read rapidly, while still exhibiting a large TER ((J ON -J OFF )/J OFF × 100%). [13] Considering the large band gap of HfO 2 (≈6 eV), the thickness of HfO 2 in the FTJ will need to be reduced to the ultrathin limit for adequate tunnel current. Tunnel junctions implementing CMOS-compatible HfO 2 -based ferroelectric barriers have been recently demonstrated, [17][18][19] but even three nanometer Zr-doped HfO 2 (Zr:HfO 2 ) barriers were found to be too thick to obtain nano-ampere level current in micron-sized capacitors. [20] Therefore, high ON current is a critical consideration; however, the increased ON state current from an ultrathin barrier will coincide with an increased OFF state current. For array-level implementations, where sneak leakage paths can lead to increased power consumption, selector devices may be required in conjunction with the FTJ memory elements to reduce such sneak currents. [13] Here, we demonstrate FTJs utilizing one nanometer Zr:HfO 2 as the ferroelectric barrier, grown by atomic layer deposition (ALD) directly on silicon, thereby scaling down the tunnel barrier ABSTRACT: In ferroelectric materials, spontaneous symmetry breaking leads to a switch-able electric polarization, which offers significant promise for nonvolatile memories. In particular, ferroelectric tunnel junctions (FTJs) have emerged as a new resistive switching memory which exploits polarizationdependent tunnel current across a thin ferroelectric barrier. This work integrates FTJs with com-plementary metal-oxide-semiconductor-compatible Zr-doped HfO 2 (Zr...

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Section: Methodsmentioning

confidence: 99%

One Nanometer HfO₂‐Based Ferroelectric Tunnel Junctions on Silicon

Cheema

Shanker

Hsu

et al. 2021

Adv Elect Materials

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“…Among various doped HfO 2 , Zr-doped HfO 2 (HZO) is particularly attractive due to its low annealing temperature and excellent scalability 25,31–34 . In FTJs based on metal/HZO/metal structure, in order to achieve a sizable on-current, the thickness of HZO needs to be scaled down below 5 nm 35,36 . However, the polarization in these ultra-thin HZO films is very small, which leads to a low TER ratio 37 .…”

Section: Introductionmentioning

confidence: 99%

Ferroelectric Tunneling Junctions Based on Aluminum Oxide/ Zirconium-Doped Hafnium Oxide for Neuromorphic Computing

Ryu

Rao

et al. 2019

Sci Rep

152

115

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Ferroelectric tunneling junctions (FTJs) with tunable tunneling electroresistance (TER) are promising for many emerging applications, including non-volatile memories and neurosynaptic computing. One of the key challenges in FTJs is the balance between the polarization value and the tunneling current. In order to achieve a sizable on-current, the thickness of the ferroelectric layer needs to be scaled down below 5 nm. However, the polarization in these ultra-thin ferroelectric layers is very small, which leads to a low tunneling electroresistance (TER) ratio. In this paper, we propose and demonstrate a new type of FTJ based on metal/Al2O3/Zr-doped HfO2/Si structure. The interfacial Al2O3 layer and silicon substrate enable sizable TERs even when the thickness of Zr-doped HfO2 (HZO) is above 10 nm. We found that F-N tunneling dominates at read voltages and that the polarization switching in HZO can alter the effective tunneling barrier height and tune the tunneling resistance. The FTJ synapses based on Al2O3/HZO stacks show symmetric potentiation/depression characteristics and widely tunable conductance. We also show that spike-timing-dependent plasticity (STDP) can be harnessed from HZO based FTJs. These novel FTJs will have high potential in non-volatile memories and neural network applications.

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“…The direct experimental evidence of the ferroelectric Pca2 1 phase was provided by scanning transmission electron microscopy [26]. These findings stimulated significant efforts in studying relevant properties of ferroelectric HfO 2 films [27][28][29][30][31][32], showing their applicability as a functional gate oxide in nanoscale FeFET memory devices [33,34] and ferroelectric tunnel junctions [35][36][37].…”

Section: Introductionmentioning

confidence: 99%

Magnetoelectric Effect at the Ni/HfO2 Interface Induced by Ferroelectric Polarization

et al. 2019

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Driven by the technological importance of the recently discovered ferroelectric HfO 2 , we explore a magnetoelectric effect at the HfO 2-based ferroelectric-ferromagnetic interface. Using density-functionaltheory calculations of the Ni/HfO 2 /Ni (001) heterostructure as a model system, we predict a stable and sizable ferroelectric polarization in a few-nm-thick HfO 2 layer. For the Ni/HfO 2 interface with opposite polarization directions (pointing to or away from the interface), we find a sizable difference in the interfacial Ni-O bonding, resulting in dissimilar degrees of depletion of the electron density around the interface. The latter affects the relative population of the exchange-split majority and minority spin bands at the interface and thus the interfacial magnetic moments. The sizable change in the interface magnetization with ferroelectric polarization reversal of HfO 2 manifests a significant ferroelectrically induced magnetoelectric effect at the Ni/HfO 2 interface. Our results reveal promising prospects of ferroelectric-ferromagnetic composite multiferroics based on HfO 2-based ferroelectric materials.

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Electron transport across ultrathin ferroelectric Hf0.5Zr0.5O2 films on Si

Cited by 69 publications

References 8 publications

One Nanometer HfO₂‐Based Ferroelectric Tunnel Junctions on Silicon

One Nanometer HfO₂‐Based Ferroelectric Tunnel Junctions on Silicon

Ferroelectric Tunneling Junctions Based on Aluminum Oxide/ Zirconium-Doped Hafnium Oxide for Neuromorphic Computing

Magnetoelectric Effect at the Ni/HfO2 Interface Induced by Ferroelectric Polarization

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Electron transport across ultrathin ferroelectric Hf0.5Zr0.5O2 films on Si

Cited by 69 publications

References 8 publications

One Nanometer HfO2‐Based Ferroelectric Tunnel Junctions on Silicon

One Nanometer HfO2‐Based Ferroelectric Tunnel Junctions on Silicon

Ferroelectric Tunneling Junctions Based on Aluminum Oxide/ Zirconium-Doped Hafnium Oxide for Neuromorphic Computing

Magnetoelectric Effect at the Ni/HfO2 Interface Induced by Ferroelectric Polarization

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One Nanometer HfO₂‐Based Ferroelectric Tunnel Junctions on Silicon

One Nanometer HfO₂‐Based Ferroelectric Tunnel Junctions on Silicon