Physical Origin of Transient Negative Capacitance in a Ferroelectric Capacitor

Chang, Sou-Chi; Avci, Uygar E.; Nikonov, Dmitri E.; Manipatruni, Sasikanth; Young, Ian A.

doi:10.1103/physrevapplied.9.014010

Cited by 72 publications

(62 citation statements)

References 25 publications

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“…The interpretation of the V ‐drop effect by the conventional FE switching model can be further supported by the disappearance of the effect during the subsequent switching cycles only up to ten times . Consistently, Chang et al showed that the mismatch in switching rate between the free charge on the metal plate and the bound charge in FE layer during the polarization switching is a physical origin of the V ‐drop effect in a ferroelectric capacitor …”

Section: Basic Concepts Of Nc From the Ferroelectric Thin Filmmentioning

confidence: 83%

Modeling of Negative Capacitance in Ferroelectric Thin Films

et al. 2019

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Section: Basic Concepts Of Nc From the Ferroelectric Thin Filmmentioning

confidence: 83%

Modeling of Negative Capacitance in Ferroelectric Thin Films

et al. 2019

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“…[25,26] Subsequently, NC has been reported in many electronic devices, such as bilayer capacitors, [91,92] p-n junctions, [27,28] Schottky diodes, [29,30] metal-insulator-metal (MIM) devices, [31] polycrystalline solar cells, [32] quantum devices, [33,34] and superlattices. [93] Besides, time-resolved measure of NC is realized in 2018. Jonscher proposed that the right way for analyzing NC is through the time-domain behavior under step function bias, which involves an initial decrease in current followed by an increase over a period before finally decaying to zero.…”

Section: Negative Capacitancementioning

confidence: 99%

Ferroelectric Negative Capacitance Field Effect Transistor

Wang

et al. 2018

Adv Elect Materials

117

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such as steep subthreshold swing (SS), high switching ratio (I on /I off ), adjustable hysteresis, compatibility with standard semiconductor fabrication processes, and environmental friendliness, promotes NCFET to be a promising candidate to lower power consumption and solve the heat problem in ULSI.As early as the 1960s, the concept of negative capacitance (NC) was proposed in amorphous semiconductor chalcogenides thin film, [25,26] then the NC effect was observed in several devices, such as p-n junctions, [27,28] Schottky diodes, [29,30] metal-insulator-metal diodes, [31] and others. [32][33][34][35] Concretely, the NC effect occurs when the reciprocal of the second derivation of potential energy U with respect to the ferroelectric polarization charge Q F is negative, which is usually achieved during the switching process of ferroelectric polarization. [36,37] NCFET achieves steep SS through the NC voltage amplification effect by adding a ferroelectric layer into the transistor gate stack. [22] NCFET simulation methods vary according to the types of transistor gate structures-metal ferroelectric semiconductor field-effect transistor (MFSFET), metal ferroelectric insulator semiconductor field-effect transistor (MFISFET), and metal ferroelectric metal insulator semiconductor field-effect transistor (MFMISFET). However, the basic principle is to realize a match between the channel charge Q and the ferroelectric polarization charge P, [38][39][40][41][42] no matter what the specific gate structure is.Furthermore, the influencing factors of NCFET's electrical properties have been qualitatively analyzed and summarized according to numerous simulation results. Commonly, a tradeoff exists between SS and hysteresis, [22] and we can design and manipulate the gate structure, [41] ferroelectric thickness (t Fe ), [22] ferroelectric material parameters, [38] silicon doping concentration, [39,43] temperature, [44] work frequency, [45][46][47][48] and high-κ dielectric [23,49,50] to optimize the electrical performance of NCFET and meet specific practical application requirement.The experimental researches on NCFETs can be mainly classified into three categories based on various kinds of ferroelectrics. First, the NCFET based on organic ferroelectric-poly(vinylidene difluoride-trifluoroethylene)[P(VDF-TrFE)], has been experimentally demonstrated, and achieves minimum SS (SS min ) = 13 mV dec −1 with small hysteresis. [51,52] Second, the NCFET based on lead zirconate titanate (PZT), a type of inorganic perovskite-type ferroelectric, exhibits hysteretic switching with With the progress in silicon circuit miniaturization, lowering power consumption becomes the major objective. Supply voltage scaling in ultralargescale integration (ULSI) is limited by the physical barrier termed "Boltzmann Tyranny." Moreover, considerable heat is inevitably generated from the ultrahighly integrated circuit. To solve these problems, a ferroelectric negative capacitance field-effect transistor (Fe-NCFET) is proposed in order to reduce the subthresho...

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“…Our recent work theoretically proved that this differential negative capacitance is driven by the free charge-polarization mismatch as qualitatively pointed out in Ref. [6], which can be well described under Landau's mean field theory [7]. In 2018, the transient differential negative capacitance has been also experimentally observed in a FE MOS capacitor [8], indicating the existence of transient mismatch between bound charge and free charge in a MOS structure.…”

mentioning

confidence: 57%

“…Similar to Ref. [7], the physical origin of this transient SS can be understood by taking the time derivative of Eq. 3 as shown below.…”

mentioning

confidence: 87%

“…Note that from Ref. [7], γ extracted from a 50 × 50µm 2 FE doped hafnium capacitor is roughly between 10 3 to 10 4 m*sec/F depending on the amount of FE domains switched throughout the film. Therefore, it is important to characterize the value of γ as a capacitor is scaled down or a new FE material is introduced for logic applications, which is beyond the scope of this letter.…”

mentioning

confidence: 91%

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Inversion Charge Boost and Transient Steep-Slope Induced by Free-Charge-Polarization Mismatch in a Ferroelectric-Metal–Oxide–Semiconductor Capacitor

Chang

Avci

Nikonov

et al. 2018

IEEE J. Explor. Solid-State Comput. Devices Circuits

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In this letter, the transient behavior of a ferroelectric (FE) metal-oxide-semiconductor (MOS) capacitor is theoretically investigated with a series resistor. It is shown that compared to a conventional high-k dielectric MOS capacitor, a significant inversion charge-boost can be achieved by a FE MOS capacitor due to a steep transient subthreshold swing (SS) driven by the free chargepolarization mismatch. It is also shown that the observation of steep transient SS significantly depends on the viscosity coefficient under Landau's mean field theory, in general representing the average FE time response associated with domain nucleation and propagation. Therefore, this letter not only establishes a theoretical framework that describes the physical origin behind the inversion charge-boost in a FE MOS capacitor, but also shows that the key feature of depolarization effect on a FE MOS capacitor should be the inversion-charge boost, rather than the steep SS (e.g., sub-60mV/dec at room temperature), which cannot be experimentally observed as the measurement time is much longer than the FE response. Finally, we outlines the required material targets for the FE response in field-effect transistors to be applicable for next-generation high-speed and low-power digital switches.The relentless pursuit of Moore's law in the past four decades leads to a significant improvement in the computing power of modern microprocessors [1]. However, as the scaling of CMOS transistors continues, the on-off current ratio is dramatically reduced, and thus the increasing static power makes the circuit design more and more difficult for high energy-efficient applications [2]. In 2008, a transistor structure using FE materials in the gate stack was proposed to improve SS through stabilizing FE negative capacitance in the steady state [3]. However, the central idea of this proposal is all based on the S-shape of polarization-electric field relation given by Landau's free energy functional, which has been under debate if it can physically describe the polarization switching in the FE oxide [4]. In 2015, a transient differential negative capacitance was reported from a circuit composed of a resistor and a FE capacitor in series [5]. Our recent work theoretically proved that this differential negative capacitance is driven by the free charge-polarization mismatch as qualitatively pointed out in Ref. [6], which can be well described under Landau's mean field theory [7]. In 2018, the transient differential negative capacitance has been also experimentally observed in a FE MOS capacitor [8], indicating the existence of transient mismatch between bound charge and free charge in a MOS structure. The effect of free charge-polarization mismatch on transient behavior of a FE transistor was qualitatively discussed in Ref. [9], where the importance of measurement time in FE transistor characterization is emphasized but no inversion charge-boost in the steady-state from a FE transistor is concluded. Hence, in this letter, a numerical model is developed to invest...

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Physical Origin of Transient Negative Capacitance in a Ferroelectric Capacitor

Cited by 72 publications

References 25 publications

Modeling of Negative Capacitance in Ferroelectric Thin Films

Modeling of Negative Capacitance in Ferroelectric Thin Films

Ferroelectric Negative Capacitance Field Effect Transistor

Inversion Charge Boost and Transient Steep-Slope Induced by Free-Charge-Polarization Mismatch in a Ferroelectric-Metal–Oxide–Semiconductor Capacitor

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