Modeling of Negative Capacitance in Ferroelectric Thin Films

Park, Hyeon Woo; Roh, Jangho; Lee, Yong Bin; Hwang, Cheol Seong

doi:10.1002/adma.201805266

Cited by 123 publications

(97 citation statements)

References 88 publications

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“…Note that the resulted zigzag Q-V F characteristics is totally different from the conventional Q-V F curve in a single FE-CAP or from the S-curve expected from the original NC theory 1 . It is also significantly different from the characteristics expected from the recent models with the multiple-domain system, in which a continuous change of polarization with the help of domain wall motion is assumed [9][10][11][12][13] . Hysteresis of the V int gain is critical for achieving steep SS FETs in advanced CMOS.…”

Section: Resultscontrasting

confidence: 63%

“…This is also consistent with the fact that no observation of the SS improvement under a small gate voltage swing has been reported so far. Finally, it is worthy of mentioning that the polarization switching kinetics depends on a specific model such as Kolmogorov-Avrami-Ishibashi or nucleation-limited switching models 31,41 , while specific switching kinetics does not necessarily lead to the total frustration of the V int enhancement effect 12 . Namely, when the depolarization field is formed due to the bound charge movement, the V int gain can be obtained in any switching kinetics cases.…”

Section: Resultsmentioning

confidence: 99%

“…Concerning NC effects in FE/PE stacks, three kinds of demonstrations have been provided experimentally so far: (i) total capacitance enhancement in the case of no internal metal between FE and PE layers [2][3][4] , (ii) transient NC effects in AC mode operation [5][6][7] , and (iii) locally stabilized NC state 8 . Several models of quasi-static NC associated with domain wall motion in a multiple-domain system have been also proposed [9][10][11][12][13] . Meanwhile, steep SS values have been demonstrated by incorporating FE/PE gate stacks into FETs with various FE materials [14][15][16] , various channel materials 15,[17][18][19] and various FET structures 14,[20][21][22][23][24] .…”

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confidence: 99%

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Stepwise internal potential jumps caused by multiple-domain polarization flips in metal/ferroelectric/metal/paraelectric/metal stack

Toriumi

2020

Nat Commun

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Negative capacitance (NC) effects in ferroelectric/paraelectric (FE/PE) stacks have been recently discussed intensively in terms of the steep subthreshold swing (SS) in field-effect transistors (FETs). It is, however, still disputable to stabilize quasi-static-NC effects. In this work, stepwise internal potential jumps in a metal/FE/metal/PE/metal system observed near the coercive voltage of the FE layer are reported through carefully designed DC measurements. The relationship of the internal potential jumps with the steep SS in FETs is also experimentally confirmed by connecting a FE capacitor to a simple metal-oxidesemiconductor FET. On the basis of the experimental results, the observed internal potential jumps are analytically modelled from the viewpoint of bound charge emission associated with each domain flip in a multiple-domain FE layer in a FE/PE stack. This view is different from the original NC concept and should be employed for characterizing FE/PE gate stack FETs.

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Section: Resultscontrasting

confidence: 63%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Stepwise internal potential jumps caused by multiple-domain polarization flips in metal/ferroelectric/metal/paraelectric/metal stack

Toriumi

2020

Nat Commun

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“…Reference [4] extended this explanation proposing that passing the negative curvature portion generates a strong depolarizing field. It is interesting that this conclusion sounds similar to the discovery that negative capacitance can exist even in statics, in a ferroelectric having dead layers [5,6] or in heterostructures of ferroelectrics with dielectrics [7][8][9][10][11], due to a depolarizing field. Moreover, Ref.…”

Section: Introductionsupporting

confidence: 67%

Universality and origin of ultrashort intrinsic negative dielectric permittivity

Prosandeev

Bellaïche

2020

Phys. Rev. B

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By recasting the definition of the dielectric constants in terms of currents, as well as using atomistic simulations and analytical derivations, we show that the dielectric permittivity can be negative at an ultrashort timescale, under perfect screening conditions and for very different materials and switching mechanisms, in line with recent experiments and modelings. In particular, we found that this effect can be due to a previously overlooked phenomenon of postswitching polarization oscillations. We also derived practical analytical formulas that can be experimentally checked.

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“…[6][7][8] showing that the soft-DW displacement can lead to an effective negative permittivity of FE in the presence of the interfacial dead layer. Further, a similar effect has been discussed and analyzed through phase-field simulations predicting a hysteresis-free NC path in FE by considering a moving DW in a metal-FE-metal capacitor 9 and DE-FE-DE superlattice 10 . Additionally, an analytical model for DW-induced NC has been proposed for DE-FE-DE superlattice in ref.…”

mentioning

confidence: 99%

Multi-Domain Negative Capacitance Effects in Metal-Ferroelectric-Insulator-Semiconductor/Metal Stacks: A Phase-field Simulation Based Study

Saha

Gupta

2020

Sci Rep

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We analyze the ferroelectric domain-wall induced negative capacitance (NC) effect in Metal-FE-Insulator-Metal (MFIM) and Metal-FE-Insulator-Semiconductor (MFIS) stacks through phase-field simulations by self-consistently solving time-dependent Ginzburg Landau equation, Poisson's equation and semiconductor charge equations. Considering Hf 0.5 Zr 0.5 o 2 as the ferroelectric material, we study 180° ferroelectric domain formation in MFIM and MFIS stacks and their polarization switching characteristics. Our analysis signifies that the applied voltage-induced polarization switching via soft domain-wall displacement exhibits non-hysteretic characteristics. In addition, the change in domain-wall energy, due to domain-wall displacement, exhibits a long-range interaction and thus, leads to a non-homogeneous effective local negative permittivity in the ferroelectric. Such effects yield an average negative effective permittivity that further provides an enhanced charge response in the MFIM stack, compared to Metal-Insulator-Metal. Furthermore, we show that the domain-wall induced negative effective permittivity is not an intrinsic property of the ferroelectric material and therefore, is dependent on its thickness, the gradient energy coefficient and the in-plane permittivity of the underlying insulator. Similar to the MFIM stack, MFIS stack also exhibits an enhanced charge/ capacitance response compared to Metal-Oxide-Semiconductor (MOS) capacitor. Simultaneously, the multi-domain state of the ferroelectric induces non-homogeneous potential in the underlying insulator and semiconductor layer. At low applied voltages, such non-homogeneity leads to the coexistence of electrons and holes in an undoped semiconductor. In addition, we show that with the ferroelectric layer being in the 180° multi-domain state, the minimum potential at the ferroelectric-dielectric interface and hence, the minimum surface potential in the semiconductor, does not exceed the applied voltage (inspite of the local differential amplification and charge enhancement). app and SS < 60 mV/decade 1. As a result, the NC effect in FE materials can potentially enable voltage scaling without affecting the drive current of FE-FET.

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Modeling of Negative Capacitance in Ferroelectric Thin Films

Abstract: His research interests include ferroelectric thin films for next-generation nonvolatile memory and computing applications and negative capacitance in ferroelectric materials for steep-slope transistors.

Cited by 123 publications

References 88 publications

Stepwise internal potential jumps caused by multiple-domain polarization flips in metal/ferroelectric/metal/paraelectric/metal stack

Stepwise internal potential jumps caused by multiple-domain polarization flips in metal/ferroelectric/metal/paraelectric/metal stack

Universality and origin of ultrashort intrinsic negative dielectric permittivity

Multi-Domain Negative Capacitance Effects in Metal-Ferroelectric-Insulator-Semiconductor/Metal Stacks: A Phase-field Simulation Based Study

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