Nanometer-thick membranes, including extreme ultraviolet (EUV) pellicles, require temporary protection during wet-based Si bulk etching. This sacrificial layer must shield the target membrane from the Si etchant and be removable after membrane fabrication. Here, sputtered Cu is introduced as a sacrificial protection layer for Mo₂C-based membrane fabrication. Cu exhibited strong resistance to a 30 wt
To achieve a reduction in the footprint and a low-thermal-budget monolithic three-dimensional (M3D) integration, the scaling and stacking of vertical-channel thin-film transistors (VTFTs) were investigated. The feasibility of vertical scaling was examined by reducing the channel length (LCH) from 150 to 40 nm via spacer thickness scaling. During the scaling process, sufficient insulation characteristics were maintained. As the LCH of the VTFTs decreased from 150 to 40 nm, the current drivability (CDR) increased from 35.3 to 74.6 μA/μm. In contrast, the threshold voltage (VTH) decreased from 0.9 to 0.43 V, while the DIBL coefficient increased from 111 to 364 mV/V, suggesting the onset of short-channel effects. Nevertheless, the device exhibited consistent switching characteristics. In consideration of the obtained results, vertically stacked VTFTs incorporating top (ST_T-VTFT) and bottom (ST_B-VTFT) devices were implemented, and their device characteristics were systematically compared with those of single devices. The CDRs of the ST_T-VTFT and ST_B-VTFT were measured to be 83.9 and 68.0 μA/μm, respectively, showing an improvement compared to the S_VTFT (55.4 μA/μm). In addition, key device parameters, including SS and DIBL, remained comparable to those of the single device. To assess structural interactions, electrical coupling in the stacked devices was found to be negligible despite the continuous active layer and shared gate-stack structure, confirming independent device operation. These findings demonstrate that a vertically-stacked VTFTs architecture can achieve both ultra-short-channel scaling and stacking while maintaining stable device performance, providing a promising strategy for low-thermal-budget M3D integration based on oxide semiconductors TFTs.
Tandem quantum-dot light-emitting diodes (QLEDs) offer a promising route to high-brightness displays, but their performance critically depends on efficient and optically transparent charge generation layers (CGLs). Here, we introduce a nanostructured ZnMgO/poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(p-butylphenyl))diphenylamine)] (TFB) bilayer CGL for solution-processed tandem QLEDs. Slowly synthesized ZnMgO nanoparticles formed a highly textured surface that was conformally covered by TFB, enlarging the effective interfacial area while providing favorable wettability and energy-level alignment. The resulting ZnMgO/TFB CGL-only device exhibited a charge-generation current density approximately 160
Despite their promise as energy storage systems, aqueous zinc batteries remain hindered by nonuniform Zn deposition and hydrogen evolution. Herein, a polydopamine (PDA) and poly(vinylidene fluoride) (PVDF) bilayer-structured Zn anode (PDA/PVDF@Zn) is developed, where PVDF is positioned adjacent to the Zn surface as a hydrophobic barrier, while PDA serves as the hydrophilic electrolyte-facing layer. By strategically positioning PDA and PVDF at different interfaces, the bilayer structure simultaneously promotes a favorable interfacial Zn2+ distribution and regulates water accessibility at the Zn interface. Compared with the corresponding single-layer PDA and PVDF coatings, as well as the reverse bilayer configuration, PDA/PVDF@Zn exhibited more stable Zn plating/stripping behavior, sustaining operation for 600 h at 1 mA cm−2 and 1 mAh cm−2. Cell swelling measurements support the suppression of hydrogen evolution in PDA/PVDF@Zn, which exhibited a 3.3-fold reduction in cell swelling compared with PDA@Zn anode. In full cell with a V2O5 cathode, PDA/PVDF@Zn anode delivered a capacity of 138 mAh g−1 after 80 cycles while maintaining a coulombic efficiency above 99.4
This study investigates the synergistic effects of Ag and Mn co-doping on the thermoelectric performance and band gap evolution of p-type Bi0.5Sb1.5Te3 alloys fabricated via scalable melting and hot-pressing. Using Bi0.5Sb1.5Te3 + 0.075 wt
Unitized regenerative fuel cells (URFCs) integrate fuel-cell and water-electrolysis modes within a single stack, enabling compact and reversible energy storage systems. Bipolar plates are key components that serve as current collectors, gas separators, flow-field supports, and structural elements, and strongly influence stack weight, volume, and ohmic losses. Conventional carbon-based plates offer low density and high electrical conductivity but are prone to carbon oxidation at the high anodic potentials used in electrolysis, leading to increased porosity, surface degradation, and elevated interfacial contact resistance. Metallic plates, particularly titanium and stainless steel, provide superior mechanical strength, reduced thickness, and excellent gas impermeability. However, oxide layer formation on their surfaces necessitates the use of conductive protective coatings to maintain low contact resistance and long-term stability under alternating redox conditions. Recent advances have focused on hybrid metal–carbon bipolar plates that combine the advantages of both material classes. These include bulk metal–carbon composites, metal substrates with carbon-rich or noble-metal coatings, and nanostructured composites incorporating carbon nanotubes or graphene networks. In these systems, performance is governed by the interplay of composition, microstructure, and surface engineering rather than any single material property. The central design strategy is hybridization: carbon components reduce mass and enhance conductivity and hydrophobicity, while metallic phases improve mechanical robustness and corrosion resistance. This review summarizes material systems, fabrication strategies, microstructural control, and corrosion mechanisms, highlighting that compositionally optimized and surface-engineered hybrid bipolar plates offer a promising route toward durable, high-performance URFC stacks.
Copper sulfide-based thermoelectric materials composed of earth-abundant and environmentally benign elements have attracted considerable attention for mid-temperature energy conversion. Bornite (Cu5FeS4), a p-type semiconductor with intrinsically low lattice thermal conductivity, is considered a promising candidate for applications in the 300–700 K temperature range. However, achieving phase-pure bornite with optimized transport properties remains challenging due to its sensitivity to processing conditions and phase stability. In this study, we systematically investigate the effect of hot pressing (HP) temperature on phase evolution, microstructure, and thermoelectric transport properties of bornite synthesized via mechanical alloying (MA). Particular emphasis is placed on understanding the relationship between phase purity, secondary phase suppression, and transport behavior. X-ray diffraction analysis reveals that secondary chalcopyrite (CuFeS2) phases form at lower HP temperatures (623–673 K), while a phase-pure bornite is obtained at 723 K, indicating that sufficient thermal energy is required for complete phase homogenization. This phase evolution is found to strongly influence both charge and thermal transport properties. Although the electrical conductivity decreases slightly with increasing HP temperature, the reduction in thermal conductivity and improved phase homogeneity lead to enhanced thermoelectric performance. The sample processed at 723 K exhibits the lowest thermal conductivity (< 0.5 W m⁻¹ K⁻¹) and achieves the highest figure of merit, with a maximum ZT of 0.65 at 723 K. These results demonstrate that precise control of HP conditions is critical for suppressing secondary phases and optimizing the balance between electrical and thermal transport, providing a practical strategy for improving the performance of bornite-based thermoelectric materials.
Achieving low-leakage and more symmetric bipolar hysteretic response in low-thermal-budget Hf0.5Zr0.5O2 (HZO) is challenging because phase stability, defect populations, and interfacial transport evolve in a coupled manner. Here, we establish a comparative framework to assess the combined roles of tetravalent dopant selection and bottom interfacial-layer insertion in pulsed-laser-deposited HZO thin films ( 19 nm) integrated into Pt/HZO/TiN capacitors without post-annealing. Within a common growth window (400 °C), 5 mol
Cryogenic etching has revolutionized the semiconductor fabrication industry by enabling the creation of High-Aspect-Ratio (HAR) structures with a high degree of precision. This review highlights the advantages of cryogenic etching over traditional etching techniques, particularly in achieving anisotropic profiles with minimal physical imperfections. It provides an in-depth analysis of mask materials used in cryogenic etching, exploring their compatibility with the cryogenic process and their potential for achieving precise etching results. Furthermore, the paper discusses innovations in mask technology, including the development of new composite materials that combine polymers with metal additives to enhance their performance in extreme conditions. The study also identifies potential defects, such as Aspect Ratio Dependent Etching (ARDE), Undercut, and Crystal Orientation Dependent Etching (CODE). It discusses the implications of these defects on process optimization. The paper also covers the application of cryogenic etching in developing advanced semiconductor device fabrication techniques, including Through-Silicon Vias (TSVs), nano-trenches, and Cryogenic Atomic Layer Etching (ALE). Overall, this review provides a comprehensive analysis of the evolution of etching techniques and highlights the advantages of cryogenic etching over traditional etching techniques in achieving high precision and integration, critical for the next generation of semiconductor devices.
Among non-volatile memories (NVMs), phase-change memory (PCM) has emerged as a promising candidate for various applications owing to its fast switching speed, scalability, and multilevel-cell (MLC) capability. Nevertheless, resistance drift in the amorphous phase remains a critical obstacle to reliable MLC operation. Although metallic liner integration has been shown to mitigate this issue in planar PCM structures, its direct application to vertically stacked 3D architectures pursued for high-density memory requires re-optimization of the liner parameters. Here, we integrate a metallic liner into a vertically stacked 3D PCM structure and conduct finite element method (FEM) simulations to identify a target thickness range of 15–25 nm based on the trade-off between resistance drift suppression and ON/OFF ratio. Based on these results, a 4-layer metallic liner-integrated vertical PCM was fabricated and electrically characterized, achieving a significant reduction in the RESET state drift coefficient at 25 ℃ while maintaining data retention comparable to the conventional device. This suppression extended across all programmed states, confirming the reliability of multilevel operation. However, the continuous metallic liner along the vertical stack introduces a potential parasitic leakage path between adjacent layers. To evaluate this effect, inter-layer read-current coupling was quantified through a simplified 1 × N stack model extended to 64 layers, with the projected mean error remaining below 1
Flexible electronic devices that can accommodate mechanical deformations during practical use have attracted significant attention. Oxide semiconductors offer long operational lifetimes, excellent stability, and favorable electrical properties. However, sol-gel-processed oxide semiconductors are inherently brittle and typically require high-temperature annealing at > 500 °C, which limits their integration with stretchable substrates that can withstand only 120–200 °C. Consequently, a low-temperature transfer process is required for the application of oxide semiconductors in stretchable electronic devices. In this study, an indium gallium zinc oxide–ethylene glycol (IGZO–EG) solution was formulated by introducing EG into an IGZO metal precursor, enabling uniform thin-film formation and mechanically stable transfer under low-temperature conditions. The prepared films were transferred onto target substrates using a polydimethylsiloxane (PDMS)-based stamp transfer method. The surface chemistry and electrical properties of the IGZO–EG thin-film transistors (TFTs) before and after transfer were quantitatively investigated using X-ray photoelectron spectroscopy, atomic force microscopy, and electrical measurements. The results demonstrate that the PDMS-based stamp transfer process enables reliable low-temperature transfer of sol-gel-based IGZO thin films while preserving their electrical characteristics. These findings confirmed the feasibility of integrating solution-processed oxide semiconductor thin films with stretchable electronic platforms via a simple and cost-effective transfer approach.
Reducing contact resistance remains a critical challenge for improving the performance of two-dimensional semiconductor-based field-effect-transistors (FETs). In this study, we investigate the effect of O2 plasma treatment on the metal/WS2 interface and its impact on device performance. The plasma treatment induces the formation of an ultrathin WO3−x interfacial layer, effectively suppresses metal-induced gap states (MIGS) and mitigates Fermi-level pinning at the contact interface. As a result, the Schottky barrier height is significantly reduced, leading to marked improvements in charge injection and transport characteristics. The optimized WS2 FET exhibited a 14.4-fold enhancement in field-effect mobility, a 799.6-fold reduction in contact resistance, and a 26.2-fold increase in on-current (ION) compared to pristine devices. These findings demonstrate that O2 plasma-induced interfacial engineering provides a scalable approach for achieving high-performance WS2–based FETs with low-contact resistance.
The development of efficient thermoelectric materials for direct waste heat–to–electricity conversion remains a major challenge, particularly for high-temperature applications. In this paper, a systematic first-principles examination of the structural, electronic, elastic, thermal and thermoelectric characteristics of double perovskite oxides, Ba2XReO6 (X = Li, Rb, Cs), is conducted using the density functional theory, alongside Boltzmann transport theory. Structural optimization proves that all compounds are thermodynamically stable in the cubic Fm3̅m phase with negative formation energies. Furthermore, ab initio molecular dynamics simulations performed at 300 K confirm the dynamical stability of the optimized structures. The electronic structure analysis reveals semiconducting behavior in Ba2CsReO6, Ba2LiReO6, and Ba2RbReO6, all exhibiting indirect and narrow band gaps, which are ideal characteristics for thermoelectric transport. The elastic constants obtained and used have met the Born stability requirements, indicating mechanical stability and ductile behavior. A systematic decrease in Debye temperature, melting temperature, and lattice thermal conductivity with increasing A-site ionic radius led to ultralow lattice thermal conductivity of Ba2RbReO6 and Ba2CsReO6. Thermoelectric transport calculations show positive Seebeck coefficients and enhanced power factors at elevated temperatures. Of the investigated compounds, the Ba2RbReO6 has the largest thermoelectric figure of merit (ZT), owing to an optimum balance between electrical conductivity and reduced thermal conductivity. Overall, our results suggest that Ba2XReO2, particularly Ba2RbReO2, are promising candidates for high-temperature thermoelectric applications.
Surface engineering via N2 plasma-based ion implantation is presented as a rapid strategy to boost the zinc-storage performance of manganese hexacyanoferrate (MnHCF) cathodes. Precise control of the plasma exposure duration is shown to be essential, with a 1-minute treatment (MnHCF-N1) providing the most significant enhancements in capacity and stability. The MnHCF-N1 electrode exhibits a high specific capacity of 130.9 mAh g-1, which represents a 20
Integrating epitaxial Pb(Zr, Ti)O3 (PZT) thin films on Si requires solving two critical challenges: crystallographic orientation control of the bottom electrode and thermal stress mismatch. This study establishes a “Ti(002)→TiO₂(004)→Pt(111)” texture inheritance pathway, combined with thermal stress modulation, to achieve high-quality epitaxial Pt(111) electrodes. The crystallographic information transfer across layers and its impact on PZT properties are systematically investigated. The texture quality of the Ti layer is amplified through the TiO2 intermediate layer: any degradation in Ti(002) orientation is magnified, leading to increased dispersion in Pt(111) orientation, which is quantitatively inherited by the PZT layer, following FWHM_PZT≈ 1.2× FWHM_Pt+0.5^∘ . By optimizing Ti sputtering and rapid thermal oxidation, a highly oriented rutile TiO2(004) buffer layer is obtained, inducing a Pt(111) electrode with FWHM as low as 1.5°. The resulting PZT films exhibit high (001) orientation, dense morphology, and excellent properties (Pr ≈ 15µC/cm²; e₃₁,f = -15.5 C/m2). Notably, Pt(111) texture critically governs PZT switching symmetry: when Pt FWHM ≤ 2°, the piezoelectric/ferroelectric curves are perfectly symmetric; for FWHM > 2°, asymmetry increases progressively. Integrating such PZT films into a C-beam piezoelectric MEMS scanning mirror achieves an optical scan angle of ± 40° at 25 Vpp, demonstrating both large deflection and symmetric scanning. This work provides a reliable fabrication route for high-performance piezoelectric MEMS and elucidates the texture and stress transfer mechanism in heteroepitaxy, offering a universal strategy for integrating complex oxide films on Si.
The effects of the dielectric curing temperature on the interfacial adhesion characteristics of the photosensitive polyimide (PSPI)/Cu redistribution layer for fan-out packages were systematically investigated using a four-point bending test. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy were used to analyze the chemical properties of PSPI. The interfacial adhesion energy increased as the curing temperature increased from 350 to 375 °C. This increase was associated with the progression of the ring-closing reaction accompanied by an increase in imide (C–N) bonding. However, when the curing temperature was further increased to 390 °C, the interfacial adhesion energy decreased, which is attributed to the partial degradation of carbonyl (C=O) bonds under excessive curing conditions. These results indicate that optimizing the curing temperature is critical to achieving reliable PSPI/Cu interfacial adhesion in FOWLP RDL structures.
Zinc oxide (ZnO) is one of the most widely used electron transport layers (ETLs) in inverted organic photovoltaics (OPVs). However, its strong photocatalytic activity and abundance of surface defects induce the generation of radical intermediates under illumination, leading to rapid degradation of nonfullerene acceptors (NFAs) and severe efficiency loss. Here, we propose a hybrid ETL composed of a fullerene derivative (C₆₀-SB) modified with a conjugated polyelectrolyte, poly[(9,9-bis(3′-(N, N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] bromide (PFN-Br), which simultaneously tunes the surface energy and reduces the effective work function (WF) of the ETL. The synergistic C₆₀-SB/PFN-Br interface forms a molecularly ordered, energetically favorable layer that promotes efficient electron extraction and suppresses photocatalytic radical formation. Devices based on C₆₀-SB/PFN-Br exhibit initial power conversion efficiency ( 9
O3-type layered oxide cathode materials have garnered substantial attention owing to their high theoretical capacity and low cost, making them one of the most promising candidates for sodium-ion battery (SIB) cathodes. Nevertheless, their practical application is hindered by insufficient structural stability and inferior rate capability. Rational morphology engineering emerges as a viable strategy to alleviate these drawbacks, as it can enlarge the Na+ interlayer spacing, increase the electroactive surface area, and thereby enhance both structural integrity and ionic transport kinetics. In this study, a co-precipitation method was adopted to regulate the morphology of the Fe0.5Mn0.5(OH)2 precursor (denoted as FM-X) by tailoring the reaction environment. The ultimately synthesized O3-Na0.87Fe0.5Mn0.5O2 cathode material (denoted as NFMO-X) exhibit distinct morphologies and microstructures. Notably, the NFMO-9.5 sample, prepared at pH = 9.5 with a hexagonal block-like morphology, possesses high crystallinity, abundant surface active sites exposed 010 planes, and an expanded Na+ interlayer spacing. These favorable characteristics endow NFMO-9.5 with the highest initial discharge specific capacity (163.61 mAh g− 1 at 0.1 C), better capacity retention rate (73
Amidst escalating global energy crises and environmental degradation, biomass resources offer a critical pathway for energy transition through their inherent renewability, carbon neutrality, and abundance. However, efficient conversion of waste biomass remains impeded by compositional complexity and suboptimal process energetics, constraining scalable industrial implementation. Building on this, we innovatively utilize waste grapefruit peel as a multifunctional precursor to construct Ni-Mo₂C heterojunction nanocomposites (Ni-Mo₂C/NGC) on a biomass-derived N-doped graphene-like carbon matrix (NGC) via an in situ one-step pyrolysis strategy. Electrocatalytic evaluation reveals that the nanocomposite exhibits outstanding bifunctional activity for both oxygen and hydrogen evolution reactions (OER/HER) in alkaline electrolyte, achieving low overpotentials (η) of 260 mV for OER and 120 mV for HER at a current density of 10 mA cm⁻², with corresponding Tafel slopes of 48 and 52 mV dec⁻¹, respectively. Density functional theory (DFT) calculations elucidate that synergistic interfacial electron coupling between Ni and Mo₂C at the heterojunction significantly elevates the density of exposed catalytic active sites, optimizes the adsorption free energy of key reaction intermediates, and accelerates interfacial charge transfer kinetics, thereby cooperatively enhancing the intrinsic bifunctional electrocatalytic activity. This study establishes a novel strategy for the high-value-oriented preparation of high-performance electrocatalysts from waste biomass, providing insights into the construction of non-precious metal bifunctional heterojunction catalysts.
Gas diffusion layers (GDLs) are important components of fuel cells, which play important roles in supporting catalyst layer, collecting current, transmitting gas and managing water reaction product in fuel cells. Due to the carbon corrosion issue, however, the durability of GDLs is still not satisfied. Herein, a duplex oxidation–reduction treatment is adopted to tune the sp3/sp2 hybridization of CNTs in GDLs. XRD, FTIR and Raman spectroscopies measurement elucidated that, the sp3/sp2 ratio of GDLs was precisely tuned by duplex oxidation–reduction treatment, which enhanced the electrochemical stability and electric conductivity of GDLs. When duplex oxidation–reduction treated GDLs were assembled to single fuel cells, a high power-density (838 mW cm−2) was achieved, which was much higher than that of untreated GDLs (571 mW cm−2). Because the output power-density of single fuel cells in this paper is similar to that of commercial GDLs assembled fuel cells (908 mW cm−2), the s–p hybridization route will provide fruitful highlights to overcome carbon corrosion and find promising applications in the fields of fuel cells.
