Negative differential capacitance in ultrathin ferroelectric hafnia

Jo, Sanghyun; Lee, Hyangsook; Choe, Duk‐Hyun; Kim, Jung-Hwa; Lee, Yun Seong; Kwon, Oh Heon; Nam, Seung‐Geol; Park, Yoonsang; Kim, Kihong; Chae, Byeong Gyu; Kim, Sang–Wook; Kang, Soo‐Jung; Moon, Taehwan; Bae, Hagyoul; Jung, Won Seok; Yun, Dong‐Jin; Jeong, Minwoo; Lee, Hyun Hwi; Cho, Yeonchoo; Lee, Kwang-Hee; Lee, Hyun Jae; Lee, Sang-Jun; Nam, Kab-Jin; Jung, Dong-Hoon; Kuh, Bong Jin; Ha, Daewon; Kim, Yongsung; Park, Seongjun; Kim, Yunseok; Lee, Eunha; Heo, Jinseong

doi:10.1038/s41928-023-00959-3

Cited by 23 publications

(8 citation statements)

References 34 publications

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“…In contrast, the stabilized NC effect can produce a hysteresis-free and steep slope transfer curve, enabling the low-power operation of transistors. Although a stabilized NC effect has been observed in metal-oxide-semiconductor capacitors [21] or in MIM capacitors via calculating the polarization response versus voltage by applying a series of pulse voltages [22] or in transistors by measuring the SS, the observation of the stabilized NC effect in MIM capacitors via capacitance enhancement is absent. The hafniumbased films represented by ferroelectric Hf 0.5 Zr 0.5 O 2 (HZO) and antiferroelectric ZrO 2 , have polycrystalline and multiphase structure when fabricated via atomic layer deposition (ALD) or chemical solution deposition (CSD) [7,[23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Observation of stabilized negative capacitance effect in hafnium-based ferroic films

Qiao,

Zhao,

Song

et al. 2024

Mater. Futures

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Negative capacitance (NC) effect has been proposed as a critical pathway to overcome the “Boltzmann tyranny” of electrons, achieve the steep slope operation of transistors, and reduce the power dissipation of current semiconductor devices. Particularly, the ferroic property in hafnium-based films with fluorite structure provides an opportunity for the application of NC effect in electronic devices. However, up to now, only transient NC effect has been confirmed in hafnium-based ferroic materials, which is usually accompanied with hysteresis and detrimental to low power operations of transistors. The stabilized NC effect enables the hysteresis-free and low power transistors, but has never been observed and demonstrated in hafnium-based films. Such an absence is closely related to the polycrystalline and multi-phase structure of hafnium-based films fabricated by atomic layer deposition or chemical solution deposition. Here, we prepare epitaxial ferroelectric Hf0.5Zr0.5O2and antiferroelectric ZrO2films with single-domain structure and observe the capacitance enhancement effect of Hf0.5Zr0.5O2/Al2O3 and ZrO2/Al2O3 capacitors than that of the isolated Al2O3capacitor, verifying the stabilized NC effect. The capacitance of Hf0.5Zr0.5O2and ZrO2is evaluated as –17.41 and –27.64 pF, respectively. The observation of stabilized NC effect in hafnium-based films sheds light on the NC studies and paves an avenue to the low-power transistors.

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Section: Introductionmentioning

confidence: 99%

Observation of stabilized negative capacitance effect in hafnium-based ferroic films

Qiao,

Zhao,

Song

et al. 2024

Mater. Futures

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“…To ensure the presence of large ferroelectricity (i.e., a significant o-phase volume ratio) in HZO thin films, the growth environment at high temperatures, specifically 700 °C, and under specific strain state is necessary. Conventional atomic layer deposition (ALD) with low growth temperature, typically around 200 °C, usually produces amorphous or low-O-phase-ratio polycrystalline HZO dielectric layers on silicon-based devices. , Unfortunately, most silicon-based devices would be damaged under high temperature fabrication, making it challenging to combine them with multifunctional HZO thin films as ferroelectric gate layers. To resolve aforementioned concerns, Zhong et al successfully produced a large-scale ferroelectric freestanding HZO (FS-HZO) membrane in 2022 .…”

Section: Introductionmentioning

confidence: 99%

Thickness-Dependent Ferroelectricity in Freestanding Hf_0.5Zr_0.5O₂ Membranes

Liu,

Chen,

Wei

et al. 2024

ACS Appl. Electron. Mater.

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In the recent years, ferroelectricity in Hf 0.5 Zr 0.5 O 2 (HZO) has been intensively studied due to its compatibility with silicon-based ferroelectric applications, high dielectric constant, and maintenance of robust ferroelectricity even at ultrathin thickness (<10 nm). This makes it a potential alternative material in ferroelectric field-effect transistors, complementary metal-oxide-semiconductor (CMOS) gate layers, and other applications. Previous studies have explained that ferroelectricity is attributed to the transformation from a tetragonal (t-phase) to orthorhombic (o-phase) structure during cooling. Conventional HZO thin films that are directly grown on silicon are polycrystalline, which reduces the polarization efficiency in CMOS devices. To address this problem, there is a demand for epitaxial freestanding HZO (FS-HZO) thin films that can be transferred without substrate constraints. In this study, we conducted comprehensive analysis of FS-HZO membranes with varying thicknesses to investigate the relationship between ferroelectric properties and thin film thickness. With monoclinic phase (m-phase) substitution, we notice a reduced o-phase fraction and gradual suppression of ferroelectricity when the thickness is over 20 nm. Owing to the large structure anisotropy, we further observed an increase in X-ray linear dichroism with increasing thickness. In addition, the dielectric constant of FS-HZO decreases by half compared to as-grown HZO due to increased leakage current from the cracks led by the freestanding process. This study presents an important method to combine oxides with silicon-based semiconductors and detailed information on various thicknesses of FS-HZO in aspects of structure and ferroelectricity, providing a potential solution to compatibility concerns in the context of nextgeneration nanoelectronics.

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“…Among these, Zr has the advantage of having a lower heat treatment temperature than other dopants and a similar atomic radius and lattice parameter to Hf, so HZO (HF 1−x Zr x O 2 ) doped with Zr in Hf is receiving a lot of attention. HZO shows ferroelectric characteristics as its crystal structure between an electrode and a ferroelectric thin film is changed by stress from a conventional monoclinic phase to an orthorhombic phase at a temperature of 400~600 • C. HZO shows the highest ferroelectricity when the composition ratio of Hf and Zr is 1:1, and since HZO is usually deposited through atomic layer deposition (ALD), the composition ratio can be controlled and thin films can be produced easily [42,43]. In addition, HZO has ferroelectric characteristics even in thin films, so it is easy to integrate into devices and is compatible with existing CMOS processes [44].…”

Section: Introductionmentioning

confidence: 99%

Recent Research for HZO-Based Ferroelectric Memory towards In-Memory Computing Applications

et al. 2023

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The AI and IoT era requires software and hardware capable of efficiently processing massive amounts data quickly and at a low cost. However, there are bottlenecks in existing Von Neumann structures, including the difference in the operating speed of current-generation DRAM and Flash memory systems, the large voltage required to erase the charge of nonvolatile memory cells, and the limitations of scaled-down systems. Ferroelectric materials are one exciting means of breaking away from this structure, as Hf-based ferroelectric materials have a low operating voltage, excellent data retention qualities, and show fast switching speed, and can be used as non-volatile memory (NVM) if polarization characteristics are utilized. Moreover, adjusting their conductance enables diverse computing architectures, such as neuromorphic computing with analog characteristics or ‘logic-in-memory’ computing with digital characteristics, through high integration. Several types of ferroelectric memories, including two-terminal-based FTJs, three-terminal-based FeFETs using electric field effect, and FeRAMs using ferroelectric materials as capacitors, are currently being studied. In this review paper, we include these devices, as well as a Fe-diode with high on/off ratio properties, which has a similar structure to the FTJs but operate with the Schottky barrier modulation. After reviewing the operating principles and features of each structure, we conclude with a summary of recent applications that have incorporated them.

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Negative differential capacitance in ultrathin ferroelectric hafnia

Cited by 23 publications

References 34 publications

Observation of stabilized negative capacitance effect in hafnium-based ferroic films

Observation of stabilized negative capacitance effect in hafnium-based ferroic films

Thickness-Dependent Ferroelectricity in Freestanding Hf_0.5Zr_0.5O₂ Membranes

Recent Research for HZO-Based Ferroelectric Memory towards In-Memory Computing Applications

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Negative differential capacitance in ultrathin ferroelectric hafnia

Cited by 23 publications

References 34 publications

Observation of stabilized negative capacitance effect in hafnium-based ferroic films

Observation of stabilized negative capacitance effect in hafnium-based ferroic films

Thickness-Dependent Ferroelectricity in Freestanding Hf0.5Zr0.5O2 Membranes

Recent Research for HZO-Based Ferroelectric Memory towards In-Memory Computing Applications

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Thickness-Dependent Ferroelectricity in Freestanding Hf_0.5Zr_0.5O₂ Membranes