Modulation of ferroelectricity and antiferroelectricity of nanoscale ZrO2 thin films using ultrathin interfacial layers

Yi, Sheng-Han; Lin, Bo‐Yen; Hsu, Tzu-Yao; Shieh, Jay; Chen, Miin-Jang

doi:10.1016/j.jeurceramsoc.2019.05.065

Cited by 42 publications

(27 citation statements)

References 42 publications

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“…The obtained values for P r and P s are comparable to those reported in the literature for orthorhombic ZrO 2 film capacitors, in which a wake-up cycle was needed. 17,22,23 In addition, the polarization values are lower than the ones found in rhombohedral 5 nm Hf 0.5 Zr 0.5 O 2 films, 12 whereas the coercive field is significantly lower (more than 3 times less), which is beneficial for technological applications. Reduction of the switching voltages of these materials is considered a key step for memory applications.…”

Section: Resultsmentioning

confidence: 93%

Wake-up Free Ferroelectric Rhombohedral Phase in Epitaxially Strained ZrO₂ Thin Films

Silva

Negrea

Istrate

et al. 2021

ACS Appl. Mater. Interfaces

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Zirconia- and hafnia-based thin films have attracted tremendous attention in the past decade because of their unexpected ferroelectric behavior at the nanoscale, which enables the downscaling of ferroelectric devices. The present work reports an unprecedented ferroelectric rhombohedral phase of ZrO2 that can be achieved in thin films grown directly on (111)-Nb:SrTiO3 substrates by ion-beam sputtering. Structural and ferroelectric characterizations reveal (111)-oriented ZrO2 films under epitaxial compressive strain exhibiting switchable ferroelectric polarization of about 20.2 μC/cm2 with a coercive field of 1.5 MV/cm. Moreover, the time-dependent polarization reversal characteristics of Nb:SrTiO3/ZrO2/Au film capacitors exhibit typical bell-shaped curve features associated with the ferroelectric domain reversal and agree well with the nucleation limited switching (NLS) model. The polarization-electric field hysteresis loops point to an activation field comparable to the coercive field. Interestingly, the studied films show ferroelectric behavior per se, without the need to apply the wake-up cycle found in the orthorhombic phase of ZrO2. Overall, the rhombohedral ferroelectric ZrO2 films present technological advantages over the previously studied zirconia- and hafnia-based thin films and may be attractive for nanoscale ferroelectric devices.

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Section: Resultsmentioning

confidence: 93%

Wake-up Free Ferroelectric Rhombohedral Phase in Epitaxially Strained ZrO₂ Thin Films

Silva

Negrea

Istrate

et al. 2021

ACS Appl. Mater. Interfaces

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“…The formation of the tetragonal, monoclinic, and orthorhombic crystalline phases in ZrO 2 thin films are influenced by doping, annealing, interfacial layers, and growth conditions. [ 34,38–42 ] There is a notable thickness dependence that causes the low permittivity monoclinic phase to appear in films thicker than 10 nm due to a grain size effect. [ 14,43 ] Higher annealing temperatures can also cause the formation of the monoclinic phase and are technologically prohibitive from the perspective of back‐end‐of‐line integration.…”

Section: Structure Of Zro2 Thin Filmsmentioning

confidence: 99%

Harnessing Phase Transitions in Antiferroelectric ZrO₂Using the Size Effect

Lomenzo

Materano

Mittmann

et al. 2021

Adv Elect Materials

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hysteresis observed in macroscopic polarization-voltage (P-V) measurements in HfO 2 and ZrO 2 thin films is a signature of AFE device functionality and originates from a complex interplay of favorable crystallization conditions. [3,5] Underlying electric field-induced FE structural phase transitions are hypothesized to be responsible for generating the distinctive features of antiferroelectricity in the fluorite material system, yet little is known about how to best exploit such phase transitions in fluorites. [4,6] Alternative theories of AFE-like behavior, such as oppositely imprinted FE domains and paraelectric-to-paraelectric phase transitions, need to be evaluated since the approach to achieve superior AFE device performance will depend on the underlying cause of macroscopic antiferroelectricity. [7][8][9][10] Due to the simplicity of controlling the film thickness, the size effect may be easily leveraged to influence and gain a better understanding of antiferroelectricity in ZrO 2 , but previous film thickness studies on ZrO 2 and Hf 1−x Zr x O 2 have not quantified the size-effect influence on supercapacitor performance. [11][12][13][14] A theory of AFE crystals was first formulated by Kittel in which two sub-lattices of opposing polarization are described by a Landau-Devonshire free energy model. [15] There is also increasing acceptance for a more general definition of antiferroelectricity to include reversible electric field induced first-order phase transitions between a paraelectric (nonpolar) and a FE (polar) phase that do not necessarily involve an antipolar crystal structure. [3,5,16,17] In this work, AFE is used in the expanded sense of the term to include field-induced phase transitions that may not specifically involve an antipolar crystal phase.While the diverse polymorphism of HfO 2 and ZrO 2 ceramics has been known for decades, [18] the emergence of a FE phase in thin films of these materials over the past decade has revealed fresh insight on new structural phases and interrelationships. [19][20][21] With the identification of the Pca2 1 polar orthorhombic (o) phase in HfO 2 thin films, [22] the possibility of electric-field induced phase transitions in fluorites surfaced with functional electronic AFE properties. [3,6,20] First-order electric field driven phase transitions between the nonpolar tetragonal and polar orthorhombic phases in HfO 2 and ZrO 2 are postulated to be the origin of antiferroelectricity inThe unique nonlinear dielectric properties of antiferroelectric (AFE) oxides are promising for advancements in solid state supercapacitor, actuator, and memory technologies. AFE behavior in high-k ZrO 2 is of particular technological interest, but the origin of antiferroelectricity in ZrO 2 remains questionable. The theory of reversible electric field-induced phase transitions between the nonpolar P4 2 /nmc tetragonal phase and the polar Pca2 1 orthorhombic phase is experimentally tested with local structural and electromechanical characterization of AFE ZrO 2 thin films. Piezoresponse f...

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“…Overall, the formation of the o- and the t-phase in thin ZrO 2 films seems to depend on different factors. For instance, electrode materials , and interface layers can play a role, but stress and strain can favor the o-phase too. In contrast, crystallization in the m-phase is often observed for atomic layer deposited (ALD)-doped HfO 2 or mixed Hf x Zr 1– x O 2 films above 20 nm. ,, …”

Section: Introductionmentioning

confidence: 99%

Influence of Si-Doping on 45 nm Thick Ferroelectric ZrO₂ Films

Lomenzo

Kersch

et al. 2022

ACS Appl. Electron. Mater.

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In the last decades, ferroelectricity has been discovered in Si-doped HfO 2 and Hf 1−x Zr x O 2 thin films, and the origin of ferroelectricity is considered to be the presence of the polar Pca2 1 orthorhombic phase. Recently, some investigations suggest that ZrO 2 thin films show ferroelectric behavior as well. As a well-known dopant capable of modulating ferroelectricity in HfO 2 thin films, Si-doping is applied up to approximately 5.3% to modify the ferroelectric properties of ZrO 2 films in this work. The atomic layer-deposited ZrO 2 films with a 45 nm thickness shows ferroelectric behavior with a remanent polarization of 7 μC/cm 2 after post-metallization annealing at 800 °C. According to Raman spectroscopy and grazing incidence X-ray diffraction structural characterizations, the amount of monoclinic and orthorhombic phases decreases, and the presence of the tetragonal phase increases by increasing the Si-doping content in the ZrO 2 films. The electrical properties both at room temperature and at lower temperature demonstrate antiferroelectric characteristics with lower remanent polarization and double hysteresis loops with Si incorporation in the 45 nm thick ZrO 2 films. An extrapolation of the Curie temperature for different Si-doping concentrations is obtained based on temperature-dependent remanent polarization measurements, showing evidence that Si dopants destabilize the polar ferroelectric phase. An increasing in-plane tensile strain with more Si-doping aids in stabilizing the tetragonal phase and leads to an improvement of antiferroelectric properties in 45 nm thick ZrO 2 .

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Modulation of ferroelectricity and antiferroelectricity of nanoscale ZrO2 thin films using ultrathin interfacial layers

Cited by 42 publications

References 42 publications

Wake-up Free Ferroelectric Rhombohedral Phase in Epitaxially Strained ZrO₂ Thin Films

Wake-up Free Ferroelectric Rhombohedral Phase in Epitaxially Strained ZrO₂ Thin Films

Harnessing Phase Transitions in Antiferroelectric ZrO₂Using the Size Effect

Influence of Si-Doping on 45 nm Thick Ferroelectric ZrO₂ Films

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Modulation of ferroelectricity and antiferroelectricity of nanoscale ZrO2 thin films using ultrathin interfacial layers

Cited by 42 publications

References 42 publications

Wake-up Free Ferroelectric Rhombohedral Phase in Epitaxially Strained ZrO2 Thin Films

Wake-up Free Ferroelectric Rhombohedral Phase in Epitaxially Strained ZrO2 Thin Films

Harnessing Phase Transitions in Antiferroelectric ZrO2Using the Size Effect

Influence of Si-Doping on 45 nm Thick Ferroelectric ZrO2 Films

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Product

Resources

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Wake-up Free Ferroelectric Rhombohedral Phase in Epitaxially Strained ZrO₂ Thin Films

Wake-up Free Ferroelectric Rhombohedral Phase in Epitaxially Strained ZrO₂ Thin Films

Harnessing Phase Transitions in Antiferroelectric ZrO₂Using the Size Effect

Influence of Si-Doping on 45 nm Thick Ferroelectric ZrO₂ Films