Critical thickness of ultrathin ferroelectric BaTiO3 films

Kim, Y. S.; Kim, D. H.; Kim, J. D.; Chang, Young Jun; Noh, Tae Won; Kong, Juwon; Char, K.; Park, Y. D.; Bu, Sang Don; Yoon, Jong‐Gul; Chung, J.-S.

doi:10.1063/1.1880443

Cited by 213 publications

(159 citation statements)

References 17 publications

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“…E C decreases with increasing thickness. This behavior is [52][53][54] and Bi 4 Ti 3 O 12 , [55][56][57][58][59][60][61] and HfO 2 9,12) and our results.…”

Section: Resultssupporting

confidence: 68%

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Polarization switching behavior of Hf–Zr–O ferroelectric ultrathin films studied through coercive field characteristics

Migita

Ota

Yamada

et al. 2018

Jpn. J. Appl. Phys.

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The electrical properties of ferroelectric Hf-Zr-O ultrathin films, particularly the dependences of remnant polarization, leakage current, coercive field, and breakdown field on the metal composition and film thickness, are systematically examined. Physical analyses show that the Hf-Zr-O films in this experiment consist of polycrystalline grains and contain both ferroelectric and dielectric phases. It is found that changes in metal composition and thickness strongly influence the remnant polarization and the leakage current simultaneously. In contrast, the coercive field was relatively unaffected by these parameters. This particular behavior of the coercive field suggests that the polarization switching in Hf-Zr-O films is predominantly determined by the nature of nanometer-scale ferroelectric domains dispersed in the films.

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“…E C decreases with increasing thickness. This behavior is [52][53][54] and Bi 4 Ti 3 O 12 , [55][56][57][58][59][60][61] and HfO 2 9,12) and our results.…”

Section: Resultssupporting

confidence: 68%

“…The relationship between E C and thickness (d) for well-known perovskite ferroelectrics, such as Pb(Zr,Ti)O 3 , [43][44][45][46][47][48] SrBi 2 Ta 2 O 9 , [49][50][51] BaTiO 3 , [52][53][54] and Bi 4 Ti 3 O 12 , [55][56][57][58][59][60][61] is plotted in Fig. 8.…”

Section: Resultsmentioning

confidence: 99%

Polarization switching behavior of Hf–Zr–O ferroelectric ultrathin films studied through coercive field characteristics

Migita

Ota

Yamada

et al. 2018

Jpn. J. Appl. Phys.

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“…Hence, the mean coercive field E c ¼ |V down -V up |/2t of the BTO film with the thickness t ¼ 3 nm ranges from 0.6 to 1 MV cm À 1 . These values are consistent with the coercive fields reported for very thin (tB5 nm) BTO films earlier 17,43,44 . This result is a strong indication of the good quality of the fabricated ultrathin BTO barrier.…”

supporting

confidence: 81%

“…The experimental realization of FTJs, however, is a difficult task, given that it requires the growth of ferroelectric nanolayers retaining switchable spontaneous polarization at a thickness of just a few unit cells. Nevertheless, high-quality epitaxial films grown on suitable substrates were found to possess necessary ferroelectric properties even at nanoscale thicknesses [14][15][16][17][18] , which may be attributed to the enhancement of the out-of-plane polarization by substrate-induced lattice strains 19 and the elastic stabilization of a single-domain state 20 . Based on these advancements, various FTJs have recently been successfully fabricated and the TER effect was revealed experimentally and confirmed theoretically [21][22][23][24][25][26][27][28][29][30][31] .…”

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confidence: 99%

Giant electrode effect on tunnelling electroresistance in ferroelectric tunnel junctions

et al. 2014

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Among recently discovered ferroelectricity-related phenomena, the tunnelling electroresistance (TER) effect in ferroelectric tunnel junctions (FTJs) has been attracting rapidly increasing attention owing to the emerging possibilities of non-volatile memory, logic and neuromorphic computing applications of these quantum nanostructures. Despite recent advances in experimental and theoretical studies of FTJs, many questions concerning their electrical behaviour still remain open. In particular, the role of ferroelectric/electrode interfaces and the separation of the ferroelectric-driven TER effect from electrochemical ('redox'-based) resistance-switching effects have to be clarified. Here we report the results of a comprehensive study of epitaxial junctions comprising BaTiO 3 barrier, La 0.7 Sr 0.3 MnO 3 bottom electrode and Au or Cu top electrodes. Our results demonstrate a giant electrode effect on the TER of these asymmetric FTJs. The revealed phenomena are attributed to the microscopic interfacial effect of ferroelectric origin, which is supported by the observation of redox-based resistance switching at much higher voltages.

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“…An ultrathin barrier results in a large tunneling current, which facilitates easy signal readout and device scaling. However, serious undesirable effects, including the FE dead layer, 22 pinned interface dipole, [23][24][25] and leakage current, 11,18,26 arise and degrade the device performance.…”

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confidence: 99%

Overcoming the Fundamental Barrier Thickness Limits of Ferroelectric Tunnel Junctions through BaTiO₃/SrTiO₃ Composite Barriers

et al. 2016

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ABSTRACT:Ferroelectric tunnel junctions (FTJs) have attracted increasing research interest as a promising candidate for non-volatile memories. Recently, significant enhancements of tunneling electroresistance (TER) have been realized through modifications of electrode materials.However, direct control of the FTJ performance through modifying the tunneling barrier has not been adequately explored. Here, adding a new direction to FTJ research, we fabricated FTJs with Ferroelectric tunnel junctions (FTJs), composed of a thin ferroelectric (FE) layer sandwiched in between two metallic electrodes, have been intensively investigated in recent years. This device is considered to be a promising candidate for next-generation nonvolatile memories, because it combines the advantages of both ferroelectric random-access-memory and resistiveswitching memory. 1-3 The concept of FTJ was first proposed by Esaki in 1971, 4 but the research activities have not flourished untixl this decade. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] The operation of FTJs has been mainly explained in terms of interfacial screening of polarization charges. [5][6][7][8] In a metal 1(M1)/FE/metal 2 (M2) structured FTJ (Figure 1a), the two asymmetric electrodes lead to unequal screen lengths and potential changes at metal/FE interfaces. Depending on the polarizations, the electrostatic potential profile of tunneling barrier will be varied. As a result, the tunneling resistance can be switched between low (ON) and high (OFF) values by polarization reversal, leading to the socalled tunneling electroresistance (TER) effect.Extensive experimental works based on this asymmetric screening scenario have been reported during the last decade. In 2009, the TER effect was first demonstrated using conducting atomic force microscopy (CAFM). 9-11 Subsequently, FTJs with highly reproducible performance were realized in capacitor geometry, which will be useful for practical applications. 12,13 Up to recently, most studies of FTJs have focused on improving device performance by modifying the electrode materials. [14][15][16][17][18][19][20] Typical examples include the use of lightly doped semiconductors, [14][15][16] For a thick barrier, these obstacles can be avoided, but the tunneling current becomes too small for realizing a practically useful device. As an alternative, several groups have theoretically proposed a new kind of FTJ using an FE/paraelectric (FE/PE) composite barrier. 27,28 The PE layer provides a new route to control the tunneling barrier potentials, and thus the TER can be tuned and significantly enhanced. However, there have been few experimental efforts to systematically attest this theoretical prediction. 29 In this paper, we report experimental control of the TER effect by directly manipulating the tunneling barrier thickness and composition. For this purpose, we fabricated two types of FTJs: Figure S5), which further confirm good epitaxial film qualities.We estimated the lattice constants of the oxide layers from XRD reci...

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Critical thickness of ultrathin ferroelectric BaTiO3 films

Cited by 213 publications

References 17 publications

Polarization switching behavior of Hf–Zr–O ferroelectric ultrathin films studied through coercive field characteristics

Polarization switching behavior of Hf–Zr–O ferroelectric ultrathin films studied through coercive field characteristics

Giant electrode effect on tunnelling electroresistance in ferroelectric tunnel junctions

Overcoming the Fundamental Barrier Thickness Limits of Ferroelectric Tunnel Junctions through BaTiO₃/SrTiO₃ Composite Barriers

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Critical thickness of ultrathin ferroelectric BaTiO3 films

Cited by 213 publications

References 17 publications

Polarization switching behavior of Hf–Zr–O ferroelectric ultrathin films studied through coercive field characteristics

Polarization switching behavior of Hf–Zr–O ferroelectric ultrathin films studied through coercive field characteristics

Giant electrode effect on tunnelling electroresistance in ferroelectric tunnel junctions

Overcoming the Fundamental Barrier Thickness Limits of Ferroelectric Tunnel Junctions through BaTiO3/SrTiO3 Composite Barriers

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Overcoming the Fundamental Barrier Thickness Limits of Ferroelectric Tunnel Junctions through BaTiO₃/SrTiO₃ Composite Barriers