Journal of Electronic Materials最新文献

Metamaterials (MTMs) are synthetic structures known for their ability to control electromagnetic wave propagation, offering innovative solutions for reducing the radar cross-section (RCS) of objects. This paper proposes an agile bilayer MTM to reduce the RCS. Each layer consists of identical agile MTM unit cells embedded with switches to achieve agility. Depending on the switch state, we can obtain two types of unit cells: connected (ON state) and disconnected (OFF state), which exhibit two different behaviors. The switches are controlled using an external command system. By independently adjusting the switching states (ON/OFF) of the two layers, six agile reflection frequency stop bands are generated, corresponding to the four possible configurations of ON–ON, ON–OFF, OFF–ON, and OFF–OFF, and their reflection and transmission ranges are controlled. This design has the capability to control six distinct frequency bands with a − 1- dBm RCS reduction, comprising two bands within the Ku-band (12–18 GHz) and four within the Ka-band (25–40 GHz).

Electronic devices and communication systems are highly susceptible to interference from unwanted electromagnetic waves. High-performance electromagnetic interference (EMI) shielding offers a solution to this issue. In this work, we discuss the design of an EMI shielding material composite using natural rubber (NR) filled with polyaniline (PANI), multi-walled carbon nanotubes (MWCNT), and ferric oxide (Fe₂O₃). Different properties of the material composite are studied using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. We tested the EMI shielding efficiency of the developed material in the X band and the Ku band. The measurements revealed improved shielding effectiveness when compared to similar microwave shielding materials. In terms of flexibility and cost-effectiveness, this novel composite also proved to be a better alternative.

Despite their advantages of light weight, complete coating and good formability, the poor high-temperature stability of organic materials limits their use as insulation coatings for soft magnetic powders. Therefore, a polyethyleneimine (PEI)/silicone resin (SR) double organic insulation layer was exploited to release internal stress and maintain insulation stability during the high-temperature annealing process, which achieved low core losses (P_cv) and high effective permeability (μ_e). Cross-sectional scanning transition images indicate that the PEI/SR layer undergoes the following evolution during annealing at 500–900°C: coating → densification → crack → rupture, implying thermal stability up to 700°C. Because of the integrity of double inorganic shells and the weak pin on magnetic domain movement, FeSiAl@PEI/SR cores annealed at 800°C deliver remarkable AC soft magnetic performance at 50 and 100 kHz, that is, low P_cv of 61.6 mW/cm³ (50 mT, 100 kHz), 121.2 mW/cm³ (100 mT, 50 kHz) and 307.3 mW/cm³ (100 mT, 100 kHz), high μ_e of 55.6 up to 1 MHz and 140°C, and DC bias of 51.5% at 100 Oe. Eddy current loss reaches the minimum value at 700°C and deteriorates at 800°C, and hysteresis loss continues to decrease with increasing annealing temperature, confirming the evolution of the insulation layer. Moreover, cores annealed at 700°C deliver μ_e of 57.6 at 1 MHz and P_cv of 278 mW/cm³ (20 mT, 1 MHz), exhibiting great potential for 1 MHz frequency power applications.

Bilayer thin films of GdFeO₃/Fe₉₇Si₃ have been synthesized by RF–magnetron sputtering at different thicknesses of GdFeO₃. A pure phase polycrystalline growth of GdFeO₃ and Fe₉₇Si₃ has been confirmed by XRD measurements. Stress-induced room-temperature magnetocrystalline anisotropy has been confirmed in all the bilayer thin films. A high magnetic moment has been induced in antiferromagnetic GdFeO₃ thin films resulting in the ferromagnetic character of all the samples. The ferromagnetic moment was found to be enhanced with increasing thickness of the GdFeO₃ layer. The maximum value of the room- temperature magnetic moment has been observed as M_s ~ 9.3 emu/ml in 170-nm-thick GdFeO₃ film. Dielectric measurements confirmed the induced magnetocapacitance due to grain boundary accumulation of charge carriers. Magnetic field control of capacitance and current–voltage measurements of these thin films represents a strong potential for the existence of magnetoelectric coupling in GdFeO₃/Fe₉₇Si₃ films. A maximum 30% rise in magnetocapacitance and a 95.6% increase in tunneling current in an applied 1-kOe magnetic field was obtained for 170-nm-thick GFO thin film. These thin films possess applications in spintronic devices due to the presence of room- temperature magnetocrystalline anisotropy and magnetic control of the electric properties.

Researchers have created a modern infrared (IR) sensor that is both super-sensitive and highly flexible. This remarkable device possesses impressive properties of exceptional sensitivity (24,000%), high responsiveness (1.25 A/W), and fast response time (3 ms). This innovation stands out for its unique construction: an ultrathin layer of lead sulfide (PbS) deposited on a standard Whatman filter paper. This design achieves a photo-current 32 times greater than previous record-holding PbS thin films. The key advantage is its unmatched flexibility. This sensor can bend and flex without breaking, maintaining its IR detection capabilities even after enduring extreme bending cycles. This breakthrough paves the way for a new era of wearable IR photo sensors, flexible electronics, and medical applications.

Aqueous zinc-ion batteries (ZIBs) with advantages of low cost, high safety, and eco-friendliness hold immense potential as large-scale energy storage devices. Nevertheless, the uncontrollable side reactions and Zn dendrites severely compromise the reversibility and stability of zinc anodes, hindering the practical application of ZIBs. In this study, glycine is introduced as a bi-functional additive into the ZnSO₄ electrolyte to address these challenges. Experimental results and theoretical calculations demonstrate that the glycine can effectively modulate the solvation structure of Zn²⁺, thereby suppressing the hydrogen evolution reaction (HER) and the formation of by-products. Additionally, glycine molecules preferentially adsorb onto the zinc anode, altering the interface between the Zn anode and the electrolyte. This increases the nucleation overpotential and inhibits the 2D diffusion of Zn²⁺, promoting the homogeneous deposition of Zn. As a result, the Zn||Zn symmetric cell with glycine additive displays a stable cycling performance for over 1500 h at 5 mA cm⁻² and 1 mA h cm⁻², and the Zn||Cu asymmetric cell exhibits a reversible plating/stripping process with the high stable coulombic efficiency (CE) of 98.4% over 600 cycles. This study offers a low-cost, efficient, and environmentally benign electrolyte additive for favorable Zn deposition.

Graphical Abstract

In this work, pretreatment with vacuum ultraviolet (VUV) light changed the adhesion strength between an epoxy resin and directly sputtered copper in a printed circuit board manufacturing process. The adhesion strength was 0.9 N/cm without irradiation but had a peak value of 2.1 N/cm at 540 mJ/cm² of VUV irradiation; with increasing VUV irradiation, the adhesion strength decreased. Based on x-ray photoelectron spectroscopy (XPS) analysis of the copper interface of copper peeled from the resin, we evaluated the abundance ratio of metallic and organic oxygen at interfaces exposed to different VUV irradiation doses. We found that the change in the abundance ratio of metallic and organic oxygen was similar to the change in adhesion strength between copper and epoxy resin after exposure to different VUV irradiation doses. We observed the interface between copper and resin via scanning transmission electron microscopy (STEM) and found a distributed layer of oxygen. The functional group concentration in STEM images suggested the presence of a material with an intermediate density. We used chemically modified XPS to evaluate changes in the functional group concentration on epoxy resin surfaces irradiated with VUV light. We found that the hydroxyl group (OH) formed by VUV irradiation and the copper formed by direct sputtering improved adhesion strength in a synergistic manner. We observed a correlation between OH concentration on the resin surface and adhesion strength. These results will help to optimize the VUV irradiation process for adhesion between epoxy resin and sputtered copper.

We report the synthesis of phosphorus (P)-doped reduced graphene oxide (P-rGO) using a hydrothermal method at 180°C for 7 h. Furthermore, the amorphous nature and phase purity of the hydrothermally synthesized P-rGO was studied by powder x-ray diffraction. The characteristic sheet-like surface structure of the P-rGO was confirmed by scanning electron microscopy. The presence of P in the P-rGO was authenticated by using energy-dispersive x-ray spectroscopy and photoelectron x-ray spectroscopy. The synthesized P-rGO was employed as a low-cost and Pt-free counter electrode material for the construction of dye-sensitized solar cells (DSSCs). The effect of annealing temperature on the construction of the DSSCs using P-rGO was also studied, and the highest power conversion efficiency of 6.3% and photocurrent density of 15.37 mA/cm² were obtained at 200°C. The platinum counter electrode-based DSSCs exhibited the power conversion efficiency of 7.4%. The performance of the P-rGO counter electrode-based DSSCs was reasonable and can be further improved by developing novel device architectures. This work proposes the simple, eco-friendly, and Pt-free counter electrode for the construction of DSSCs with a decent performance.

This work is focused on fabricating a counter electrode (CE) for application in a dye-sensitized solar cell (DSSC). Cobalt manganese oxide (CoMn₂O₄) nanoparticles (NPs) and its nanocomposite with graphene were prepared by a hydrothermal method. The nanocomposites of cobalt manganese oxide with graphene as CoMn₂O₄/(graphene)_x (where x = 0.2, 0.4, and 0.6) were synthesized as an electrode material, and a cell was fabricated for the x = 0.6 nanocomposite to investigate the activity for use in DSSCs. These nanocomposites were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX), and Fourier transform infrared (FTIR) spectroscopy. SEM analysis revealed the nature of the particles, and the average grain size was in good agreement with XRD results. EDX showed the ratio of the respective samples. The XRD pattern showed the hexagonal structure of CoMn₂O₄ NPs with an average size of 39.45 nm. The FTIR spectrum indicated O–H stretching bonds and the vibrational bending of MnO at the interstitial sites. For electrochemical analysis, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were performed. Through CV analysis, an anodic peak current (I_pa) was observed at 41.42 µA, while the cathodic peak current (I_pc) was observed at −37.13 µA, and peak-to-peak separation (ΔE_pp) = 0.31 V for CoMn₂O₄ NPs. For graphene, I_pa = 180.45 µA, I_pc = −230 µA, and ΔE_pp = 0.25 V, while I_pa = 100.23 µA, I_pc = 80.65 µA, and ΔE_pp = 0.16 V for the CoMn₂O₄/graphene (x = 0.6) nanocomposite, which also showed excellent electrocatalytic properties. The charge transfer mechanism on the surface of the electrode was found to have rapid oxidation–reduction behavior and can be used as an alternative to platinum as the CE in the DSSC. The CV analysis of the CoMn₂O₄/graphene (x = 0.6) nanocomposite-based DSSC showed that the I_pa current was observed at 26.85 mA, while the I_pc current was observed at −27.25 mA in the two-electrode system. The R_s values for CoMn₂O₄/graphene with x = 0.2, 0.4, and 0.6 were 142.80 Ω, 141.33 Ω, 135.18 Ω, and 131.18 Ω, respectively, as an electrode material. The exchange current density J = 2.13 × 10⁻³ A/cm² was found using the charge transfer resistance value (R_ct = 6.03 Ω cm²) and was verified by the Tafel curve.

Graphical Abstract

Hysteresis window observed in ferroelectric negative capacitance field-effect transistors (NCFETs) have been a persistent challenge in the development of reliable logic circuits, often leading to abnormal operational conditions. Despite its significance, the underlying factors driving this hysteresis phenomenon remain elusive. In this study, we employ the quasi-static L–K equation in conjunction with the Mott–Gurney law to study the impact of V_O⁺⁺ migration on the hysteresis behavior of NCFETs, based on a surface potential-based physical model. Compared with pristine NCFET, the difference of peak voltages in value of 1.3 V was achieved in V_O⁺⁺-involved sample upon reverse and forwards scanning. This result clearly suggests that the relaxation of charged oxygen vacancies significantly affects the threshold voltage under applied sweeping voltages, providing a plausible explanation for the emergence of hysteresis windows in NCFETs. A replacement of the conventional oxide layer with a buffer layer containing high-mobility ions is proposed to adjust the hysteresis window. Importantly, in accordance with the theoretical predictions, the increased ion mobility results in a substantial reduction in the hysteresis window observed in NCFETs. Our proposed physical mechanism, elucidating the space-charge-induced hysteresis behavior, provides fresh insights for mitigating hysteresis effects, thereby advancing the potential applications of NCFETs in logic circuits.