Ferroelectricity in Si‐Doped HfO<sub>2</sub> Revealed: A Binary Lead‐Free Ferroelectric

Martin, D.; Müller, Johannes; Schenk, Tony; Arruda, Thomas M.; Kumar, Amit; Strelcov, Evgheni; Yurchuk, Ekaterina; Müller, Stefan; Pohl, Darius; Schröder, Uwe; Kalinin, Sergei V.; Mikolajick, Thomas

doi:10.1002/adma.201403115

Cited by 156 publications

(117 citation statements)

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“…3 Martin et al also examined the origin of the wakeup effect in Si:HfO 2 films based on HRTEM analysis and reported that the partial phase transition from the m-to o-phase was the reason for the wake-up effect. 5 In the current work, it is also believed that the redistribution of charged defects, such as oxygen vacancies or m-to o-phase transition, might be caused due to the increase in P r and E c during the wake-up process. On the other hand, the E int , which can be calculated by averaging the positive and negative E c values, also changed during the wake-up field cycling.…”

Section: Resultsmentioning

confidence: 97%

Study on the internal field and conduction mechanism of atomic layer deposited ferroelectric Hf_0.5Zr_0.5O₂ thin films

Park

Kim

et al. 2015

J. Mater. Chem. C

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The internal field (E int ) in ferroelectric films is an important factor which can affect the reliability of practical devices utilizing two memory states which results from the remanent polarizations of ferroelectric films. In the current work, the E int in TiN/Hf 0.5 Zr 0.5 O 2 /TiN capacitors was controlled by changing the annealing atmosphere (N 2 , O 2 , and forming gas). The magnitude of negative E int in O 2 -annealed samples was the largest, whereas that in the forming gas-annealed sample was the smallest. The magnitude of E int can be understood based on the asymmetric distribution of oxygen vacancies near top and bottom TiN electrodes. Despite the large magnitude of E int , the two remanent polarizations can be reliably retained due to the large coercive electric field of Hf 0.5 Zr 0.5 O 2 films, and this is expected to be beneficial for application in semiconductor memory devices. During the repetitive electric field cycling for the wake-up process, the change in E int in O 2 -and forming gas-annealed samples showed the opposite tendency: the magnitude of E int in the O 2 -annealed Hf 0.5 Zr 0.5 O 2 film decreased, whereas that in the forming gas-annealed film increased. This difference is believed to be due to the redistribution of oxygen vacancies with electric field high enough for the migration of oxygen vacancies. The conduction mechanism of electrons through Hf 0.5 Zr 0.5 O 2 films was also examined, and the results fitted best with the Poole-Frenkel emission model with the shallow traps for all the samples with a reasonable optical dielectric constant value for Hf 0.5 Zr 0.5 O 2 .

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Section: Resultsmentioning

confidence: 97%

Study on the internal field and conduction mechanism of atomic layer deposited ferroelectric Hf_0.5Zr_0.5O₂ thin films

Park

Kim

et al. 2015

J. Mater. Chem. C

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“…Higher activation value of the transformation rate into the m-phase for PMA samples clearly demonstrates that the TiN capping layer posed a higher activation energy barrier upon t-to-m phase transformation. [43,44] To sum up, both the JMA and NLT models effectively showed that the capping layer generated a higher kinetic energy barrier and hampered the nucleation of the m-phase within HZO thin film. [5][6][7][8][10][11][12][39][40][41][42] Compared to the reported activation energy value of 1.2 eV f.u.…”

Section: Resultsmentioning

confidence: 99%

Nucleation‐Limited Ferroelectric Orthorhombic Phase Formation in Hf_0.5Zr_0.5O₂ Thin Films

Lee

Hyun

Kim

et al. 2018

Adv Elect Materials

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Various possibilities have been proposed as the cause of the doped‐ or undoped‐HfO2 thin film materials showing unusual ferroelectricity. These assumptions are based on empirical results, yet finding the origin of the unprecedented ferroelectricity within HfO2 has suffered from a serious gap between its theoretical calculation, mostly based on thermodynamic approach and the actual experimental results. To fill the gap, this study proposes to consider the kinetic energy, providing the evidence of the kinetic energy barrier upon a phase transformation from the tetragonal phase to the monoclinic phase affected by the TiN top electrode (capping layer). 10 nm thick Hf0.5Zr0.5O2 thin films are deposited and annealed with or without the TiN capping layer with subsequent annealing at different time and temperature. Arrhenius plot is constructed to obtain the activation energy for the tetragonal‐to‐monoclinic phase transformation by calculating the amount of the transformed phase using X‐ray diffraction pattern. Johnson–Mehl–Avrami and nucleation‐limited transformation models are utilized to describe the characteristic nucleation and growth time and calculate the activation energy for the monoclinic phase transformation of the Hf0.5Zr0.5O2 thin film. Both models demonstrate that the TiN capping layer provides a kinetic energy barrier for tetragonal‐to‐monoclinic phase transformation and enhances the ferroelectric property.

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“…Furthermore, ferroelectricity can also be achieved in HfO 2 -ZrO 2 solid-solution [2]. Apart from macroscopic polarization/strain hysteresis measurements and micro-structural analyses of the phase transition, conclusive evidences for the existence of intrinsic ferroic behavior have also been provided by mesoscopic piezoresponse force microscopy (PFM) experiments [3] and first principles calculation [4][5][6][7].…”

Section: Introductionmentioning

confidence: 98%

Electric field and temperature scaling of polarization reversal in silicon doped hafnium oxide ferroelectric thin films

et al. 2015

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HfO2-based binary lead-free ferroelectrics show promising properties for non-volatile memory applications, providing that their polarization reversal behavior is fully understood. In this work, temperature-dependent polarization hysteresis measured over a wide applied field range has been investigated for Si-doped HfO2 ferroelectric thin films. Our study indicates that in the low and medium electric field regimes (E < twofold coercive field, 2E(c)), the reversal process is dominated by the thermal activation on domain wall motion and domain nucleation; while in the high-field regime (E > 2E(c)), a non-equilibrium nucleation-limited-switching mechanism dominates the reversal process. The optimum field for ferroelectric random access memory (FeRAM) applications was determined to be around 2.0 MV/cm, which translates into a 2.0 V potential applied across the 10 nm thick films

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Ferroelectricity in Si‐Doped HfO₂ Revealed: A Binary Lead‐Free Ferroelectric

Cited by 156 publications

References 26 publications

Study on the internal field and conduction mechanism of atomic layer deposited ferroelectric Hf_0.5Zr_0.5O₂ thin films

Study on the internal field and conduction mechanism of atomic layer deposited ferroelectric Hf_0.5Zr_0.5O₂ thin films

Nucleation‐Limited Ferroelectric Orthorhombic Phase Formation in Hf_0.5Zr_0.5O₂ Thin Films

Electric field and temperature scaling of polarization reversal in silicon doped hafnium oxide ferroelectric thin films

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Ferroelectricity in Si‐Doped HfO2 Revealed: A Binary Lead‐Free Ferroelectric

Cited by 156 publications

References 26 publications

Study on the internal field and conduction mechanism of atomic layer deposited ferroelectric Hf0.5Zr0.5O2 thin films

Study on the internal field and conduction mechanism of atomic layer deposited ferroelectric Hf0.5Zr0.5O2 thin films

Nucleation‐Limited Ferroelectric Orthorhombic Phase Formation in Hf0.5Zr0.5O2 Thin Films

Electric field and temperature scaling of polarization reversal in silicon doped hafnium oxide ferroelectric thin films

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Ferroelectricity in Si‐Doped HfO₂ Revealed: A Binary Lead‐Free Ferroelectric

Study on the internal field and conduction mechanism of atomic layer deposited ferroelectric Hf_0.5Zr_0.5O₂ thin films

Study on the internal field and conduction mechanism of atomic layer deposited ferroelectric Hf_0.5Zr_0.5O₂ thin films

Nucleation‐Limited Ferroelectric Orthorhombic Phase Formation in Hf_0.5Zr_0.5O₂ Thin Films