Robust Threshold-Switching Behavior Assisted by Cu Migration in a Ferroionic CuInP<sub>2</sub>S<sub>6</sub> Heterostructure

Zhong, Zhang; Wu, Shuaiqin; Li, Xiang; Wang, Zhiqiang; Yang, Qianyi; Huang, Boxian; Chen, Yan; Wang, Xudong; Lin, Tie; Shen, Hong; Meng, Xiangjian; Wang, Ming; Shi, Wei; Wang, Jianlu; Chu, Junhao; Huang, Huei Li

doi:10.1021/acsnano.3c02406

Cited by 17 publications

(7 citation statements)

References 58 publications

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“…To gain insight into the mechanism of resistive switching in the In/CuCrS 2 /Au device, we perform the temperature-dependent I–V sweep of an In/CuCrS 2 /Au device (Figure S6). As one can see, the on/off ratio becomes evident when heating to 200 K. When the temperature is <200 K, Cu ions are frozen in fixed sites by a potential well of [CuS 6 ] units, while Cu ions acquire enough energy to escape when it comes above 200 K. This is similar to the behavior of the Cu ion in ferroionic CuInP 2 S 6 . − CuInP 2 S 6 has been proven to activate its ionic conductance pathways at 250 K. Consequently, we can attribute the sudden shift in conductivity (Figure c) to the defrosting of Cu ions. On the basis of the results presented above, we can see that the performance of the device is closely related to the movement of Cu ions.…”

mentioning

confidence: 59%

van der Waals Epitaxial Growth of One-Unit-Cell-Thick Ferroelectric CuCrS₂ Nanosheets

Zhou,

Cheng,

Wang

et al. 2024

Nano Lett.

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Ferroelectric two-dimensional (2D) materials with a high transition temperature are highly desirable for new physics and nextgeneration memory electronics. However, the long-range polar order of ferroelectrics will barely persist when the thickness reaches the nanoscale. In this work, we synthesized 2D CuCrS 2 nanosheets with thicknesses down to one unit cell via van der Waals epitaxy in a chemical vapor deposition system. A combination of transmission electron microscopy, secondharmonic generation, and Raman spectroscopy measurements confirms the R3m space group and noncentrosymmetric structure. Switchable ferroelectric domains and obvious ferroelectric hysteresis loops were created and visualized by piezoresponse force microscopy. Theoretical calculation helps us understand the mechanism of ferroelectric switching in CuCrS 2 nanosheets. Finally, we fabricated a ferroelectric memory device that achieves an on/off ratio of ∼10 2 and remains stable after 2000 s, indicating its applicability in novel nanoelectronics. Overall, 2D CuCrS 2 nanosheets exhibit excellent ferroelectric properties at the nanoscale, showing great promise for next-generation devices.

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mentioning

confidence: 59%

van der Waals Epitaxial Growth of One-Unit-Cell-Thick Ferroelectric CuCrS₂ Nanosheets

Zhou,

Cheng,

Wang

et al. 2024

Nano Lett.

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“…Therefore, we have measured highresolution I-V switching curves of the Ag/SF/Au memristor (Figure 2g) and obtained an SS of less than 0.01 mV dec −1 , which is the smallest SS to the best of our knowledge (benchmarked in Figure 2h). [43][44][45][46][47][48][49][50][51][52] The pulse-mode measurement further showed a sub-100 ns resistive switching speed (Figure 2i), corresponding to a low operation energy of ≈14 pJ. The switching speed of Agbased memristors is mainly limited by the Ag ions' transport velocity in the insulating layer, which was controlled by the applied electric field.…”

Section: Resultsmentioning

confidence: 96%

Achieving Reliable and Ultrafast Memristors via Artificial Filaments in Silk Fibroin

Li,

Wang,

et al. 2023

Advanced Materials

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The practical implementation of memristors in neuromorphic computing and biomimetic sensing suffers from unexpected temporal and spatial variations due to the stochastic formation and rupture of conductive filaments (CFs). Here, the biocompatible silk fibroin (SF) is patterned with an on‐demand nanocone array by using thermal scanning probe lithography (t‐SPL) to guide and confine the growth of CFs in the silver/SF/gold (Ag/SF/Au) memristor. Benefiting from the high fabrication controllability, cycle‐to‐cycle (temporal) standard deviation of the set voltage for the structured memristor is significantly reduced by ≈95.5% (from 1.535 to 0.0686 V) and the device‐to‐device (spatial) standard deviation is also reduced to 0.0648 V. Besides, the statistical relationship between the structural nanocone design and the resultant performance is confirmed, optimizing at the small operation voltage (≈0.5 V) and current (100 nA), ultrafast switching speed (sub‐100 ns), large on/off ratio (104), and the smallest switching slope (SS < 0.01 mV dec−1). Finally, the short‐term plasticity and leaky integrated‐and‐fire behavior are emulated, and a reliable thermal nociceptor system is demonstrated for practical neuromorphic applications.

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“…These insights will help in strain engineering the ferroelectric properties , by tuning the CIPS composition. Furthermore, lattice strain can be an effective way to control the high ionic mobility of the Cu + ions under fields − and, thereby, expand the breadth of device applications based on this unique and highly interesting layered ferroelectric material.…”

Section: Discussionmentioning

confidence: 99%

Investigating Strain between Phase-Segregated Domains in Cu-Deficient CuInP₂S₆

Rao,

Selhorst,

Jiang

et al. 2023

Chem. Mater.

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CuInP 2 S 6 (CIPS) is an emerging layered ferroelectric material with a Curie temperature above room temperature. When synthesized with Cu deficiencies (i.e., Cu 1−x In 1+x/3 P 2 S 6 ), the material segregates into CIPS and In 4/3 P 2 S 6 (IPS) self-assembled heterostructures within the same single crystal. This segregation results in significant in-plane and out-of-plane strains between the CIPS and IPS phases as the volume fraction of the CIPS (IPS) domains shrinks (grows) with a decreasing Cu fraction. Here, we synthesized CIPS with varying amounts of Cu (x = 0, 0.2, 0.3, 0.4, 0.5, 0.7, 0.8, and 1) and measured the strains between the CIPS and IPS phases through the evolution of the respective Raman, infrared, and optical reflectance spectra. Density functional theory calculations revealed vibrational modes that are unique to the CIPS and IPS phases, which can be used to distinguish between the two phases through two-dimensional Raman mapping. A comparison of the composition-dependent frequencies and intensities of the CIPS and IPS Raman peaks showed interesting trends with a decreasing CIPS phase fraction (i.e., Cu/In ratio). Our data reveal red-and blueshifted Raman and infrared peak frequencies that we correlate to lattice strains arising from the segregation of the material into CIPS and IPS chemical domains. The strain is highest for a Cu/In ratio of 0.33 (Cu 0.4 In 1.2 P 2 S 6 ), which we attribute to the equal and opposite strains that the CIPS and IPS phases exert on each other. In addition, the bandgaps we extracted from the optical reflectance spectra revealed a decrease in values, with Cu 0.4 In 1.2 P 2 S 6 having the lowest value of ∼2.3 eV.

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Robust Threshold-Switching Behavior Assisted by Cu Migration in a Ferroionic CuInP₂S₆ Heterostructure

Cited by 17 publications

References 58 publications

van der Waals Epitaxial Growth of One-Unit-Cell-Thick Ferroelectric CuCrS₂ Nanosheets

van der Waals Epitaxial Growth of One-Unit-Cell-Thick Ferroelectric CuCrS₂ Nanosheets

Achieving Reliable and Ultrafast Memristors via Artificial Filaments in Silk Fibroin

Investigating Strain between Phase-Segregated Domains in Cu-Deficient CuInP₂S₆

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Robust Threshold-Switching Behavior Assisted by Cu Migration in a Ferroionic CuInP2S6 Heterostructure

Cited by 17 publications

References 58 publications

van der Waals Epitaxial Growth of One-Unit-Cell-Thick Ferroelectric CuCrS2 Nanosheets

van der Waals Epitaxial Growth of One-Unit-Cell-Thick Ferroelectric CuCrS2 Nanosheets

Achieving Reliable and Ultrafast Memristors via Artificial Filaments in Silk Fibroin

Investigating Strain between Phase-Segregated Domains in Cu-Deficient CuInP2S6

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Product

Resources

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Robust Threshold-Switching Behavior Assisted by Cu Migration in a Ferroionic CuInP₂S₆ Heterostructure

van der Waals Epitaxial Growth of One-Unit-Cell-Thick Ferroelectric CuCrS₂ Nanosheets

van der Waals Epitaxial Growth of One-Unit-Cell-Thick Ferroelectric CuCrS₂ Nanosheets

Investigating Strain between Phase-Segregated Domains in Cu-Deficient CuInP₂S₆