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9 pages, 5236 KiB

Open AccessArticle

Magnetocaloric Effect in 3D Gd(III)-Oxalate Coordination Framework

by Fang-Wen Lv, Mei-Xin Hong, Xue-Ting Wang, Haiquan Tian, Chun-Chang Wang and Xiu-Ying Zheng

Nanomaterials 2025, 15(1), 32; https://doi.org/10.3390/nano15010032 - 28 Dec 2024

Viewed by 730

Abstract

Cryogenic magnetic refrigerants based on the magnetocaloric effect (MCE) hold significant potential as substitutes for the expensive and scarce He-3. Gd(III)-based complexes are considered excellent candidates for low-temperature magnetic refrigerants. We have synthesized a series of Ln(III)-based metal-organic framework (MOF) Ln-3D (Ln = [...] Read more.

Cryogenic magnetic refrigerants based on the magnetocaloric effect (MCE) hold significant potential as substitutes for the expensive and scarce He-3. Gd(III)-based complexes are considered excellent candidates for low-temperature magnetic refrigerants. We have synthesized a series of Ln(III)-based metal-organic framework (MOF) Ln-3D (Ln = Gd/Dy) by the slow release of oxalates in situ from organic ligands (disodium edetate dehydrate (EDTA-2Na) and thiodiglycolic acid). Structural analysis shows that the Ln-3D is a neutral 3D framework with one-dimensional channels connected by [Ln(H₂O)₃]³⁺ as nodes and C₂O₄²⁻ as linkers. Magnetic measurements show that Gd-3D exhibits very weak antiferromagnetic interactions with a maximum −ΔS_m value of 36.6 J kg⁻¹ K⁻¹ (−ΔS_v = 74.47 mJ cm⁻³ K⁻¹) at 2 K and 7 T. The −ΔS_m value is 28.4 J kg⁻¹ K⁻¹ at 2 K and 3 T, which is much larger than that of commercial Gd₃Ga₅O₁₂ (GGG), indicating its potential as a low-temperature magnetic refrigerant. Full article

(This article belongs to the Special Issue Nanoelectronics: Materials, Devices and Applications (Second Edition))

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12 pages, 5359 KiB

Open AccessArticle

Electrical Characteristics of Solution-Based Thin-Film Transistors with a Zinc-Tin Oxide/Carbon Nanotube Stacked Nanocomposite Active Layer

by Yong-Jae Kim and Woon-Seop Choi

Nanomaterials 2025, 15(1), 22; https://doi.org/10.3390/nano15010022 - 27 Dec 2024

Viewed by 580

Abstract

A stacked nanocomposite zinc-tin oxide/single-walled carbon nanotubes (ZTO/SWNTs) active layer was fabricated for thin-film transistors (TFTs) as an alternative to the conventional single-layer structure of mixed ZTO and SWNTs. The stacked nanocomposite of the solution-processed TFTs was prepared using UV/O₃ treatment and [...] Read more.

A stacked nanocomposite zinc-tin oxide/single-walled carbon nanotubes (ZTO/SWNTs) active layer was fabricated for thin-film transistors (TFTs) as an alternative to the conventional single-layer structure of mixed ZTO and SWNTs. The stacked nanocomposite of the solution-processed TFTs was prepared using UV/O₃ treatment and multiple annealing steps for each layer. The electrical properties of the stacked device were superior to those of the single-layer TFT. The ZTO/SWNT TFT, fabricated using a stacked structure with ZTO on the top and SWNT at the bottom layer, showed a significant improvement in the field-effect mobility of 15.37

{cm}^{2} / V \cdot s

(factor of three increase) and an I_on/I_off current ratio of 8.83 ×

10^{8}

with improved hysteresis. This outcome was attributed to the surface treatment and multiple annealing of the selected active layer, resulting in improved contact and a dense structure. This was also attributed to the controlled dispersion of SWNT, as electron migration paths without dispersants. This study suggests the potential expansion of applications, such as flexible electronics and low-cost fabrication of TFTs. Full article

(This article belongs to the Special Issue Nanoelectronics: Materials, Devices and Applications (Second Edition))

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13 pages, 3209 KiB

Open AccessEditor’s ChoiceArticle

Permanent Strain Engineering of Molybdenum Disulfide Using Laser-Driven Stressors for Energy-Efficient Resistive Switching Memory Devices

by Heeyoon Jang, Seok-Ki Hyeong, Byeongjin Park, Tae-Wook Kim, Sukang Bae, Sung Kyu Jang, Yonghun Kim and Seoung-Ki Lee

Nanomaterials 2024, 14(23), 1872; https://doi.org/10.3390/nano14231872 - 22 Nov 2024

Viewed by 1064

Abstract

Strain engineering provides an attractive approach to enhance device performance by modulating the intrinsic electrical properties of materials. This is especially applicable to 2D materials, which exhibit high sensitivity to mechanical stress. However, conventional methods, such as using polymer substrates, to apply strain [...] Read more.

Strain engineering provides an attractive approach to enhance device performance by modulating the intrinsic electrical properties of materials. This is especially applicable to 2D materials, which exhibit high sensitivity to mechanical stress. However, conventional methods, such as using polymer substrates, to apply strain have limitations in that the strain is temporary and global. Here, we introduce a novel approach to induce permanent localized strain by fabricating a stressor on SiO₂/Si substrates using fiber laser irradiation, thereby enabling precise control of the surface topography. MoS₂ is transferred onto this stressor, which results in the application of ~0.8% tensile strain. To assess the impact of the internal strain on the operation of ReRAM devices, the flat-MoS₂-based and the strained-MoS₂-based devices are compared. Both devices demonstrate forming-free, bipolar, and non-volatile switching characteristics. The strained devices exhibit a 30% reduction in the operating voltage, which can be attributed to bandgap narrowing and enhanced carrier mobility. Furthermore, the strained devices exhibit nearly a two-fold improvement in endurance, presumably because of the enhanced stability from lattice release effect. These results emphasize the potential of strain engineering for advancing the performance and durability of next-generation memory devices. Full article

(This article belongs to the Special Issue Nanoelectronics: Materials, Devices and Applications (Second Edition))

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15 pages, 4314 KiB

Open AccessArticle

TCAD Simulation of Resistive Switching Devices: Impact of ReRAM Configuration on Neuromorphic Computing

by Seonggyeom Kim and Jonghwan Lee

Nanomaterials 2024, 14(23), 1864; https://doi.org/10.3390/nano14231864 - 21 Nov 2024

Viewed by 1644

Abstract

This paper presents a method for modeling ReRAM in TCAD and validating its accuracy for neuromorphic systems. The data obtained from TCAD are used to analyze the accuracy of the neuromorphic system. The switching behaviors of ReRAM are implemented using the kinetic Monte [...] Read more.

This paper presents a method for modeling ReRAM in TCAD and validating its accuracy for neuromorphic systems. The data obtained from TCAD are used to analyze the accuracy of the neuromorphic system. The switching behaviors of ReRAM are implemented using the kinetic Monte Carlo (KMC) approach. Realistic ReRAM characteristics are obtained through the use of the trap-assisted tunneling (TAT) model and thermal equations. HfO₂-Al₂O₃-based ReRAM offers improved switching behaviors compared to HfO₂-based ReRAM. The variation in conductance depends on the structure of the ReRAM. The conductance extracted from TCAD is validated in the neuromorphic system using the MNIST (Modified National Institute of Standards and Technology) dataset. Full article

(This article belongs to the Special Issue Nanoelectronics: Materials, Devices and Applications (Second Edition))

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10 pages, 5839 KiB

Open AccessArticle

The Influence of Etching Method on the Occurrence of Defect Levels in III-V and II-VI Materials

by Kinga Majkowycz, Krzysztof Murawski, Małgorzata Kopytko, Krzesimir Nowakowski-Szkudlarek, Marta Witkowska-Baran and Piotr Martyniuk

Nanomaterials 2024, 14(19), 1612; https://doi.org/10.3390/nano14191612 - 9 Oct 2024

Cited by 1 | Viewed by 1256

Abstract

The influence of the etching method on the occurrence of defect levels in InAs/InAsSb type-II superlattice (T2SLs) and MCT photodiode is presented. For both analyzed detectors, the etching process was performed by two methods: wet chemical etching and dry etching using an ion [...] Read more.

The influence of the etching method on the occurrence of defect levels in InAs/InAsSb type-II superlattice (T2SLs) and MCT photodiode is presented. For both analyzed detectors, the etching process was performed by two methods: wet chemical etching and dry etching using an ion beam (RIE—reactive ion etching). The deep-level transient spectroscopy (DLTS) method was used to determine the defect levels occurring in the analyzed structures. The obtained results indicate that the choice of etching method affects the occurrence of additional defect levels in the MCT material, but it has no significance for InAs/InAsSb T2SLs. Full article

(This article belongs to the Special Issue Nanoelectronics: Materials, Devices and Applications (Second Edition))

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11 pages, 1606 KiB

Open AccessArticle

Josephson Diode Effect in Parallel-Coupled Double-Quantum Dots Connected to Unalike Majorana Nanowires

by Yu-Mei Gao, Hu Xiao, Mou-Hua Jiang, Feng Chi, Zi-Chuan Yi and Li-Ming Liu

Nanomaterials 2024, 14(15), 1251; https://doi.org/10.3390/nano14151251 - 25 Jul 2024

Cited by 2 | Viewed by 1432

Abstract

We study theoretically the Josephson diode effect (JDE) when realized in a system composed of parallel-coupled double-quantum dots (DQDs) sandwiched between two semiconductor nanowires deposited on an s-wave superconductor surface. Due to the combined effects of proximity-induced superconductivity, strong Rashba spin–orbit interaction, and [...] Read more.

We study theoretically the Josephson diode effect (JDE) when realized in a system composed of parallel-coupled double-quantum dots (DQDs) sandwiched between two semiconductor nanowires deposited on an s-wave superconductor surface. Due to the combined effects of proximity-induced superconductivity, strong Rashba spin–orbit interaction, and the Zeeman splitting inside the nanowires, a pair of Majorana bound states (MBSs) may possibly emerge at opposite ends of each nanowire. Different phase factors arising from the superconductor substrate can be generated in the coupling amplitudes between the DQDs and MBSs prepared at the left and right nanowires, and this will result in the Josephson current. We find that the critical Josephson currents in positive and negative directions are different from each other in amplitude within an oscillation period with respect to the magnetic flux penetrating through the system, a phenomenon known as the JDE. It arises from the quantum interference effect in this double-path device, and it can hardly occur in the system of one QD coupled to MBSs. Our results also show that the diode efficiency can reach up to

50 %

, but this depends on the overlap amplitude between the MBSs, as well as the energy levels of the DQDs adjustable by gate voltages. The present model is realizable within current nanofabrication technologies and may find practical use in the interdisciplinary field of Majorana and Josephson physics. Full article

(This article belongs to the Special Issue Nanoelectronics: Materials, Devices and Applications (Second Edition))

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19 pages, 9067 KiB

Open AccessArticle

Infrared Lightwave Memory-Resident Manipulation and Absorption Based on Spatial Electromagnetic Wavefield Excitation and Resonant Accumulation by GdFe-Based Nanocavity-Shaped Metasurfaces

by Cheng Chen, Chuang Zhang, Taige Liu, Zhe Wang, Jiashuo Shi and Xinyu Zhang

Nanomaterials 2024, 14(14), 1230; https://doi.org/10.3390/nano14141230 - 20 Jul 2024

Viewed by 831

Abstract

An arrayed nanocavity-shaped architecture consisting of the key GdFe film and SiO₂ dielectric layer is constructed, leading to an efficient infrared (IR) absorption metasurface. By carefully designing and optimizing the film system configuration and the surface layout with needed geometry, a desirable [...] Read more.

An arrayed nanocavity-shaped architecture consisting of the key GdFe film and SiO₂ dielectric layer is constructed, leading to an efficient infrared (IR) absorption metasurface. By carefully designing and optimizing the film system configuration and the surface layout with needed geometry, a desirable IR radiation absorption according to the spatial magnetic plasmon modes is realized experimentally. The simulations and measurements demonstrate that GdFe-based nanocavity-shaped metasurfaces can be used to achieve an average IR absorption of ~81% in a wide wavelength range of 3–14 μm. A type of the patterned GdFe-based nanocavity-shaped metasurface is further proposed for exciting relatively strong spatial electromagnetic wavefields confined by a patterned nanocavity array based on the joint action of the surface oscillated net charges over the charged metallic films and the surface conductive currents including equivalent eddy currents surrounding the layered GdFe and SiO₂ materials. Intensive IR absorption can be attributed to a spatial electromagnetic wavefield excitation and resonant accumulation or memory residence according to the GdFe-based nanocavity-shaped array formed. Our research provides a potential clue for efficiently responding and manipulating and storing incident IR radiation mainly based on the excitation and resonant accumulation of spatial magnetic plasmons. Full article

(This article belongs to the Special Issue Nanoelectronics: Materials, Devices and Applications (Second Edition))

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Review

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14 pages, 3214 KiB

Open AccessReview

Research on Flexible Sensors for Wearable Devices: A Review

by Jihong Liu and Hongming Liu

Nanomaterials 2025, 15(7), 520; https://doi.org/10.3390/nano15070520 - 30 Mar 2025

Viewed by 804

Abstract

With the development of new materials and the trend of miniaturization of smart devices, wearable devices are playing an increasingly important role in people’s lives and occupying a larger market share. Meanwhile, the operation of wearable devices is based on the flexible sensors [...] Read more.

With the development of new materials and the trend of miniaturization of smart devices, wearable devices are playing an increasingly important role in people’s lives and occupying a larger market share. Meanwhile, the operation of wearable devices is based on the flexible sensors inside them. Although the development of flexible sensors has been very rapid in the more than 20 years since entering the 21st century, facing the booming market and demand at present, the development of flexible sensors still faces many challenges such as more miniaturization, higher integration, greater sustainability, high precision, and more efficient energy saving. This paper aims to summarize the development of flexible sensors, look forward to the future development of such devices, and provide a reference for researchers. Full article

(This article belongs to the Special Issue Nanoelectronics: Materials, Devices and Applications (Second Edition))

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