Leakage mechanism in ferroelectric Hf0.5Zr0.5O2 epitaxial thin films

Cheng, Xian‐Long; Zhou, Chao; Lin, Baichen; Yang, Zhenni; Chen, Shanquan; Zhang, Kelvin H. L.; Chen, Zuhuang

doi:10.1016/j.apmt.2023.101804

Cited by 6 publications

(4 citation statements)

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“…Electronics 2024, 12, x FOR PEER REVIEW 8 of 11 film, a phenomenon that the Al buffer layer helps mitigate. It is hypothesized that the heightened leakage current may stem from the formation cracks in the HZO ferroelectric film during bending [24]. The results indicate a decline in ferroelectricity for the flexible device without the Al buffer layer at the inward bending radius of 8 mm, with 2Pr diminishing to 20.2 µC/cm 2 after 100 inward bending cycles.…”

Section: Resultsmentioning

confidence: 93%

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The Excellent Bending Limit of a Flexible Si-Based Hf0.5Zr0.5O2 Ferroelectric Capacitor with an Al Buffer Layer

Xie,

Qi,

Wang

et al. 2023

Electronics

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Flexible Si-based Hf0.5Zr0.5O2 (HZO) ferroelectric devices exhibit numerous advantages in the internet of things (IoT) and edge computing due to their low-power operation, superior scalability, excellent CMOS compatibility, and light weight. However, limited by the brittleness of Si, defects are easily induced in ferroelectric thin films, leading to ferroelectricity degradation and a decrease in bending limit. Thus, a solution involving the addition of an ultra-thin Al buffer layer on the back of the device is proposed to enhance the bending limit and preserve ferroelectric performance. The device equipped with an Al buffer layer exhibits a 2Pr value of 29.5 μC/cm2 (25.1 μC/cm2) at an outward (inward) bending radius of 5 mm, and it experiences a decrease to 22.1 μC/cm2 (16.8 μC/cm2), even after 6000 bending cycles at a 12 mm outward (inward) radius. This outstanding performance can be attributed to the additional stress generated by the dense Al buffer layer, which is transmitted to the Si substrate and reduces the bending stress on the Si substrate. Notably, the diminished bending stress leads to a reduced crack growth in ferroelectric devices. This work will be beneficial for the development of flexible Si-based ferroelectric devices with high durability, fatigue resistance, and functional mobility.

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Section: Resultsmentioning

confidence: 93%

“…The stress induced during bending contributes to damage within the HZO ferroelectric film, a phenomenon that the Al buffer layer helps mitigate. It is hypothesized that the heightened leakage current may stem from the formation cracks in the HZO ferroelectric film during bending [24].…”

Section: Resultsmentioning

confidence: 99%

The Excellent Bending Limit of a Flexible Si-Based Hf0.5Zr0.5O2 Ferroelectric Capacitor with an Al Buffer Layer

Xie,

Qi,

Wang

et al. 2023

Electronics

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“…In order to investigate the electrical transport properties of B1 thin films at high electric fields (400–900 kV/cm), three possible conduction models, Poole–Frenkel (PF) emission, Schottky emission (SE), and Fowler–Nordheim (FN) tunneling, are used to fit the J – E curves (Figure S11). In the PF emission and SE emission fitted curves, although both ln( J / E ) and ln( J / T 2 ) can be used with E 1/2 can be fitted to a straight line, it is necessary to compare the optical permittivity (ε opt ) extracted by the slope. According to the literature, the refractive index of the BFMO-based film is about 3.4, and the corresponding ε opt should be 11.56 .…”

Section: Resultsmentioning

confidence: 99%

Colossal Ferroelectric Photovoltaic Effect in Inequivalent Double-Perovskite Bi₂FeMnO₆ Thin Films

Liu,

Tu,

Fang

et al. 2024

J. Am. Chem. Soc.

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Double perovskite films have been extensively studied for ferroelectric order, ferromagnetic order, and photovoltaic effects. The customized ion combinations and ordered ionic arrangements provide unique opportunities for bandgap engineering. Here, a synergistic strategy to induce chemical strain and charge compensation through inequivalent element substitution is proposed. A-site substitution of the barium ion is used to modify the chemical valence and defect density of the two B-site elements in Bi2FeMnO6 double perovskite epitaxial thin films. We dramatically increased the ferroelectric photovoltaic effect to ∼135.67 μA/cm2 from 30.62 μA/cm2, which is the highest in ferroelectric thin films with a thickness of less than 100 nm under white-light LED irradiation. More importantly, the ferroelectric polarization can effectively improve the photovoltaic efficiency of more than 5 times. High-resolution HAADF-STEM, synchrotron-based X-ray diffraction and absorption spectroscopy, and DFT calculations collectively demonstrate that inequivalent ion plays a dual role of chemical strain (+1.92 and −1.04 GPa) and charge balance, thereby introducing lattice distortion effects. The reduction of the oxygen vacancy density and the competing Jahn–Teller distortion of the oxygen octahedron are the main phenomena of the change in electron–orbital hybridization, which also leads to enhanced ferroelectric polarization values and optical absorption. The inequivalent strategy can be extended to other double perovskite systems and applied to other functional materials, such as photocatalysis for efficient defect control.

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“…4f illustrates the conduction mechanisms responsible for the leakage current produced in the HfO 2 film. Extensive studies have worked on these mechanisms, including the Poole-Frenkel (PF) emission, Schottky emission, trap-assisted tunneling (TAT), Fowler-Nordheim (FN) tunneling, and space charge limited current [20,[88][89][90]. However, the precise mechanism could not be explained without considering the contribution of traps.…”

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confidence: 99%

Role of oxygen vacancies in ferroelectric or resistive switching hafnium oxide

Lee,

Yang,

Kwon

et al. 2023

Nano Convergence

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HfO2 shows promise for emerging ferroelectric and resistive switching (RS) memory devices owing to its excellent electrical properties and compatibility with complementary metal oxide semiconductor technology based on mature fabrication processes such as atomic layer deposition. Oxygen vacancy (Vo), which is the most frequently observed intrinsic defect in HfO2-based films, determines the physical/electrical properties and device performance. Vo influences the polymorphism and the resulting ferroelectric properties of HfO2. Moreover, the switching speed and endurance of ferroelectric memories are strongly correlated to the Vo concentration and redistribution. They also strongly influence the device-to-device and cycle-to-cycle variability of integrated circuits based on ferroelectric memories. The concentration, migration, and agglomeration of Vo form the main mechanism behind the RS behavior observed in HfO2, suggesting that the device performance and reliability in terms of the operating voltage, switching speed, on/off ratio, analog conductance modulation, endurance, and retention are sensitive to Vo. Therefore, the mechanism of Vo formation and its effects on the chemical, physical, and electrical properties in ferroelectric and RS HfO2 should be understood. This study comprehensively reviews the literature on Vo in HfO2 from the formation and influencing mechanism to material properties and device performance. This review contributes to the synergetic advances of current knowledge and technology in emerging HfO2-based semiconductor devices. Graphical Abstract

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Leakage mechanism in ferroelectric Hf0.5Zr0.5O2 epitaxial thin films

Cited by 6 publications

References 61 publications

The Excellent Bending Limit of a Flexible Si-Based Hf0.5Zr0.5O2 Ferroelectric Capacitor with an Al Buffer Layer

The Excellent Bending Limit of a Flexible Si-Based Hf0.5Zr0.5O2 Ferroelectric Capacitor with an Al Buffer Layer

Colossal Ferroelectric Photovoltaic Effect in Inequivalent Double-Perovskite Bi₂FeMnO₆ Thin Films

Role of oxygen vacancies in ferroelectric or resistive switching hafnium oxide

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Leakage mechanism in ferroelectric Hf0.5Zr0.5O2 epitaxial thin films

Cited by 6 publications

References 61 publications

The Excellent Bending Limit of a Flexible Si-Based Hf0.5Zr0.5O2 Ferroelectric Capacitor with an Al Buffer Layer

The Excellent Bending Limit of a Flexible Si-Based Hf0.5Zr0.5O2 Ferroelectric Capacitor with an Al Buffer Layer

Colossal Ferroelectric Photovoltaic Effect in Inequivalent Double-Perovskite Bi2FeMnO6 Thin Films

Role of oxygen vacancies in ferroelectric or resistive switching hafnium oxide

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Colossal Ferroelectric Photovoltaic Effect in Inequivalent Double-Perovskite Bi₂FeMnO₆ Thin Films