Search Results (225)

Background: The optical losses in the form of reflections, parasitic absorption, and scattering limit photovoltaic efficiency. This review examines plasma-assisted surface engineering as an effective tool for improving light management in solar cells. Plasma-based methods, including etching, oxidation, deposition, and texturing, enable precise control of surface morphology and chemistry, lowering reflectance, enhancing light trapping, and passivating defects. Methods: In contrast to wet-chemical or high-temperature processes, plasma processes are dry, low-temperature, scalable, and can be used with silicon, perovskite, thin-film, and organic solar cells, as well as tandem structures. The fundamentals of optical losses are described, along with the principles of radio-frequency (RF), inductively coupled plasma (ICP), microwave, and atmospheric plasma systems and their distinctive advantages for controlling ion and reactive-species generation. Key applications reviewed include black-silicon texturing by ICP reactive-ion etching (ICP-RIE), anti-reflective/passivation coatings by plasma-enhanced chemical vapor deposition (PECVD), and interface activation by atmospheric plasma. Results: Among performance improvements are a reflectance of less than 2%, a photocurrent increase of 10–20%, and longer carrier lifetime. Conclusions: The advantages of plasma compared to lithography and sol–gel processes are in the precision and affordability of the method. The difficulties include damage caused by the processing, uniformity over extensive areas, and environmental stress resistance. Future directions rely on low-temperature plasmas for flexible PV, machine-learning-guided process optimization, and hybrid plasma–laser systems. This synthesis of otherwise fragmented studies is intended to support the implementation of plasma-based methods in next-generation, high-efficiency, and sustainable solar production. Full article

(1) Background: This study aimed to assess how two different adhesive solvent evaporation techniques affect the microtensile bond strength (µTBS) of a universal adhesive to dentin, as well as the enzymatic activity of dentinal matrix metalloproteinases (MMPs) at baseline and after 6-month aging under simulated pulpal pressure. (2) Methods: Middle-depth dentin surfaces of 32 sound extracted human molars were bonded under simulated pulpal pressure using a universal adhesive (Clearfil Universal Bond Quick) in either etch-and-rinse (ER) or self-etch (SE) mode. Two solvent evaporation approaches were compared: evaporation with a disposable air/water syringe (air) and with a disposable suction device (suction), yielding four experimental groups (n = 8): ER/air, ER/suction, SE/air, and SE/suction. After light-curing for 10 s, a 4 mm composite build-up was created. Specimens were stored in distilled water under simulated pulpal pressure at 37 °C for either 24 h (T0) or 6 months (T6) and then sectioned into sticks and subjected to µTBS testing. Fracture surfaces were examined by scanning electron microscopy (SEM). An additional subset of teeth from each group (n = 3) underwent in situ zymographic analysis, in which bonded sticks were ground and exposed to fluorescein-conjugated gelatin, with enzymatic activity quantified by confocal microscopy. Statistical analysis was performed at a significance threshold of p < 0.05. (3) Results: Air-drying yielded significantly higher µTBS values than suction drying, irrespective of adhesive application mode (p < 0.05). At T6, SE groups retained bond strength values comparable to baseline (p > 0.05), whereas ER groups showed a significant reduction in bond strength with aging (p < 0.05). The ER mode and suction were associated with significantly increased MMP activity at T0 (p < 0.05), while there were no differences between SE/ER at T6 (p > 0.05), and air increased MMP activity (p < 0.05). (4) Conclusions: When using an ethanol-based universal adhesive under pulpal pressure, evaporation with a disposable air syringe combined with the self-etch application mode appears to offer greater bonding reliability and stability. Full article

Composite vortex beams (CVBs) with multiple spatial singularities and orbital angular momentum (OAM) are widely used in various applications including multiple optical traps and optical communication. Here, based on the equal-angle segmentation and radial displacement modulation approach, we propose an innovative scheme for generating CVBs with controllable OAM spectrum by proposing a simple and compact optical element termed as single-helicity annulus-sector spiral zone plates (SASZPs). Theoretical analysis reveals that by modulating the structural parameters of the SASZPs, such as the topological charge, the radial misalignment parameter and the number of annulus-sector primitives, an attractive intensity pattern consisting of petal-like structures can not only be produced but also the mode purity of CVBs can also be flexibly controlled. In addition, by adopting the high-quality and low-defect diamond substrate we have synthesized, based on the electron beam lithography technology and dry etching technology, the SASZP samples with different parameters have been fabricated and the focusing properties of such optics in the visible light region have been carried out and verified. These findings direct a new avenue for improving the performance of ultra-compact solar-blind UV imaging, optical communication and integrated optics. Full article

Total internal reflection (TIR) loss is a critical bottleneck limiting light extraction in AlGaN-based deep-ultraviolet (DUV) light-emitting diodes (LEDs), primarily due to the large refractive-index contrast at the light-emitting interface. Here, pyramid-shaped dielectric metasurfaces are designed and fabricated at the sapphire/air interface of flip-chip AlGaN-based DUV LEDs using a scalable nanoimprinting process. The metasurface functions as a light outcoupling layer that modifies the interfacial momentum-matching condition and redistributes photon propagation directions. Experimental results and theoretical simulations show that metasurfaces with different feature sizes enhance light extraction through distinct mechanisms. The subwavelength pyramid nanoarray perturbs the local optical field and provides additional in-plane momentum components, facilitating the coupling of high-angle photons into radiative channels, whereas the larger pyramid void structure mainly promotes photon extraction through geometrical redirection, tilted output interfaces, and dry-etching-induced rough surface scattering. As a result, an average light output power (LOP) enhancement of over 8% is achieved for AlGaN-based DUV LEDs emitting at approximately 275 nm. This work demonstrates a low-cost, scalable, and effective strategy for enhancing the LEE of DUV LEDs, with promising potential for high-efficiency ultraviolet optoelectronic application. Full article

Recent advances in chiplet architectures, heterogeneous integration, 2.5D/3D packaging, high-performance computing, and RF applications have increased the demand for high-density vertical interconnects and low-loss packaging platforms. Glass substrates have attracted considerable attention for next-generation advanced packaging because of their low dielectric loss, high dimensional stability, smooth surface, and compatibility with large-area panel-level processing. Through-glass vias (TGVs) are essential vertical interconnect structures that enable the electrical integration of glass substrates. This focused review summarizes TGV technologies for glass-based advanced packaging from the perspectives of via formation, seed layer deposition, metallization, Cu filling, defect formation, reliability, and plugging-based alternative architectures. Representative TGV formation methods, including laser drilling, selective laser etching, laser-induced deep etching, wet/dry etching, and photosensitive glass processing, are compared. Metallization approaches based on sputtering, electroless plating, ALD/CVD, and hybrid processes are discussed together with Cu electroplating strategies such as conformal plating, bottom-up filling, pulse or pulse-reverse plating, and engineered-geometry filling. Key defects, including voids, seams, pinch-off, seed discontinuity, Cu/glass interfacial delamination, glass cracking, and Cu protrusion, are reviewed in relation to thermomechanical reliability. Finally, polymer/dielectric plugging, plugging/re-drilling, conductive paste plugging, and hybrid Cu/plugging structures are discussed as application-specific alternatives for balancing electrical performance, reliability, manufacturability, yield, and cost. Full article

Silicon micromachining serves as the foundational enabling technology for high-precision MEMS inertial sensors. However, the relentless pursuit of enhanced sensitivity and multi-functionality in emerging applications encounters a fundamental bottleneck when confined to two-dimensional scaling. The evolution toward complex three-dimensional (3D) stacking architectures is an inevitable trajectory for devices including MEMS inertial sensors, yet performance is constrained by the limitations of conventional processes in fabricating and integrating intricate 3D hollow structures. Specifically, uniformity in large-area deep silicon etching, structural integrity of convex corners in wet etching, and residual stress induced by multi-layer wafer bonding have emerged as critical, shared challenges. To address these issues, this paper proposes a triple-layer wafer-level stacking scheme that synergistically combines wet/dry hybrid etching with low-temperature adhesive bonding. This stacking scheme incorporates an innovative linear compensation model for wet-etched convex corners, enabling high-precision fabrication of complex corner structures under deep etching conditions. Furthermore, a collaborative strategy involving temporary bonding and plasma flow-field optimization improves the uniformity and integrity of dry etching for large perforated structures. A low-temperature triple-layer wafer-level stacking process is developed, encompassing precise adhesive dispensing, optical alignment, and a stepped low-temperature curing profile, thereby achieving highly symmetric 3D integration with controlled adhesive distribution. The efficacy of this stacking scheme is validated through the fabrication of a symmetrically stacked triple-layer MOEMS accelerometer sensing element. Test results demonstrate a noise floor as low as 0.40 µg/√Hz and a bias instability of 1.81 µg over 10 min. Compared with a double-layer counterpart, improved performance is obtained. The wafer-level stacking scheme established in this work not only provides a viable pathway for pushing the manufacturing limits of high-precision inertial devices but also offers a generic methodology for tackling complex hollow structure formation and low-temperature integration, holding referential value for broader applications in high-precision 3D microsystems. Full article

This study explores the influence of MXene solution as an interfacial liquid on the output performance of a Cu/n-Si-based direct current triboelectric nanogenerator (DC-TENG) system. The ${\mathrm{Ti}}_3{\mathrm{AlC}}_2$ MAX phase was successfully transformed into ${\mathrm{Ti}}_3{\mathrm{C}}_2{\mathrm{T}}_{\mathrm{x}}$ MXene through selective etching and was confirmed by scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS) and X-ray diffraction (XRD) analyses, which revealed an increase in d-spacing from 8.99 to 9.58 Å and a transition from dense layered grains to delaminated, sheet-like structures. Electrochemical impedance spectroscopy (EIS) demonstrated a pronounced reduction in impedance with the introduction of MXene solution, indicating enhanced interfacial conductivity and charge transfer capability. The presence of MXene in deionized (DI) water led to the formation of an electrical double layer (EDL) at the Cu/n-Si interface, contributing to additional interfacial capacitance and more efficient charge relaxation dynamics. As a result, the DC-TENG output was significantly enhanced with the incorporation of MXene into the system, exhibiting a markedly higher current compared to the dry contact condition. Moreover, the MXene solution helped suppress charge decay compared to dry interfaces, highlighting its role as an effective liquid medium for stabilizing surface charge and improving interfacial electron transport in DC-TENG systems. Full article

Freestanding graphene exhibits exceptional mechanical flexibility and electrical conductivity, making it well suited for varying capacitance applications. For example, when suspended above a fixed electrode, graphene will move in response to an applied bias voltage, thereby forming a varactor or voltage-controlled capacitor. In this work, we present a very detailed and scalable fabrication process for building graphene-based variable capacitor device structures. Starting with commercially available 100 mm silicon wafers with a thick thermal oxide layer, we fabricate thousands of individually accessible freestanding graphene variable capacitors using standard semiconductor methods. The process begins with metal deposition to establish alignment crosshairs, then oxide etching to create trenches, a second metal deposition to form electrodes and bonding pads, followed by large-area graphene transfer, then patterning the graphene via oxygen plasma etching, critical point drying for suspension, and finally wire bonding our devices into a package. We use optical and atomic force microscopy characterization to confirm our design specifications were met. Electrical characterization confirms successful graphene suspension through voltage-dependent capacitance measurements. The procedure presented here successfully suspends both pure multilayer graphene as well as graphene with a thick layer of PMMA. Full article

With the advancement of computing and transmission technologies, there has been a growing demand for quartz oscillators and resonators, whose performance is evaluated by the quality coefficient (Figure of Merit, FoM). High-frequency, miniaturized fabrication is the design goal, and process optimization and innovative design methods need to be emphasized. Based on the 1978 Institute of Electrical and Electronics Engineers standard definition, the old design parameters of AT-cut quartz crystal sheet are retained to analyze the structural loss factor, dielectric loss factor, frequency, admittance, quality factor, and error value with the fundamental frequency increased from 76.8 to 96 MHz. In this study, COMSOL Multiphysics is used to simulate and analyze the quartz resonator by introducing the femtosecond laser quartz microvia machining technique from the literature, improving the electrode and inverted wet etching process, and incorporating the structural loss factor and dielectric loss factor into the quartz resonator model to observe the changes in the quality factor, the percentage of the quality factor error, and the values of the eigen-frequency and the error of the frequency. We analyze the trend of loss factor, frequency value, and error value and analyze the process advantages and disadvantages of femtosecond laser drilling electrodes, coated electrodes, inverted wet etching, inverted dry etching, and single-side and double-side etching to provide a reference for the design of future process components. Full article

Dental implants have become common for restoring function and aesthetics after edentulism, with titanium (Ti) remaining the most widely used material due to its excellent mechanical properties and biocompatibility. Despite their clinical success, long-term performance is strongly influenced by surface characteristics, which regulate osseointegration and susceptibility to bacterial colonisation. Consequently, surface modification approaches have become critical strategies to enhance implant stability, bioactivity and longevity. This review critically evaluates conventional, advanced, and hybrid surface modification strategies. Subtractive methods, such as sandblasting and acid etching, increase microroughness (Ra 1.5–3 μm), enhancing osteoblast attachment and differentiation, but may promote bacterial adhesion and surface contamination. Combined treatments like SLA and SLActive generate hierarchical micro–nano topographies, improving protein adsorption, early-stage osteoblast proliferation (up to 2-fold), and clinical stability. Laser ablation and photofunctionalisation further modulate surface chemistry and wettability, accelerating osseointegration and epithelial cell adhesion. Coating approaches, including layer-by-layer self-assembly, nanospray drying, plasma spraying, and piezoelectric nanocomposites, introduce antimicrobial activity (>95% reduction in Escherichia coli or Staphylococcus aureus) and enhanced osteogenic differentiation with mechanical stability, with adhesion values reaching 49 MPa. Hybrid techniques such as sol–gel, hydrothermal, and anodisation provide controlled topography, chemical composition, and bioactivity, promoting early bone-to-implant contact (BIC increase of 10%–25%) in preclinical models. Notwithstanding promising in vitro and in vivo outcomes, variability in processing parameters and limited standardisation restrict large-scale clinical translation. Overall, contemporary Ti surface engineering emphasises a synergistic balance of topography, chemistry, wettability, and hierarchical structuring to optimise biological performance for dental implant applications. Full article

High-Al-content AlGaN microrods represent an effective platform for engineering deep-ultraviolet (DUV) emission. Here, we fabricated AlGaN microrods with varying diameters (2, 3, and 4 μm) via a top-down approach involving inductively coupled plasma dry etching followed by a KOH wet chemical modification. Their crystallographic facets and size-dependent optical properties were systematically investigated using scanning electron microscopy (SEM), cathodoluminescence (CL) spectroscopy, and CL mapping. We found that the KOH treatment selectively forms a-plane-dominated sidewalls on the high-Al-content portion of the microrods, whereas the etch pit bottoms stabilize as m-plane facets. Notably, the CL spectra show that the band-edge emission intensity of the 2 μm microrods is enhanced by a factor of 3.76 compared to the 4 μm structures. CL mapping further unveils the competitive dynamics between radiative recombination within the quantum wells and non-radiative recombination at surface states. These findings pinpoint 2 μm as the optimal diameter among the investigated range for maximizing spontaneous emission from these high-Al-content AlGaN microrods. Full article

Potassium-ion batteries hold great promise for large-scale energy storage, but their commercialization is hindered by the large ionic radius of potassium, which causes sluggish kinetics and severe volume expansion in anode materials. To address this, we present a scalable spray-drying strategy coupled with NaCl salt-templating to synthesize hierarchical porous carbon/vanadium sulfide microspheres (p-V₃S₄/C MS). In this structure, V₃S₄ nanoparticles are uniformly encapsulated within a dextrin-derived amorphous carbon matrix, and pores are formed via selective NaCl etching. This unique architecture accommodates volume fluctuations while providing rapid ion diffusion pathways. As a result, the p-V₃S₄/C MS anode exhibits outstanding electrochemical performance, maintaining a reversible capacity of 107 mA h g⁻¹ after 2000 cycles at 2.0 A g⁻¹, and achieves a high pseudocapacitive contribution of 93% at 2.0 mV s⁻¹. Furthermore, a full cell paired with a Prussian blue (PB) cathode demonstrates practical viability and robust reversibility. Our findings demonstrate that this structural engineering effectively mitigates internal resistance and structural degradation, offering a cost-effective route for mass-producing high-performance anodes for next-generation energy storage. Full article

From 4G to 5G to 6G, every few years, a new generation of data transmission technology emerges to meet the growing demand for faster and more efficient communication. Artificial intelligence, the Internet of Things and the increasing need for global connectivity are the key drivers of this evolution, pushing both research and industry toward ever-higher data rates. These advanced technologies already consume vast amounts of resources and energy, relying on high-tech nano-fabrication processes such as metal–organic chemical vapor deposition, dry etching, deposition and lithography, all of which typically occur in energy-intensive cleanroom environments. This study evaluates the epitaxy process of GaN on SiC for high-electron-mobility transistor (HEMT) devices and integrated circuits using life cycle assessment. GaN HEMTs offer high efficiency and excellent thermal conductivity, paving the way for reduced chip footprints for lower energy consumption. This analysis enables informed decision-making regarding sustainability by providing detailed data and interpretation of Fraunhofer IAF’s GaN-on-SiC HEMT technology. Full article

This in vitro study evaluated the shear bond strength (SBS) and adhesive remnant index (ARI) of orthodontic molar tubes bonded using conventional, hydrophilic, and self-etch adhesives under dry and saliva-contaminated conditions, while also assessing the impact of shear force direction. Extracted molars were bonded with Transbond XT™ (T), Transbond MIP™ (M), or Scotchbond Universal™ (S) under dry or saliva-contaminated conditions. Debonding was performed at 90° or 45°, introducing a clinically relevant but underexplored variable in orthodontic bond-strength testing. ARI scores were assessed via stereomicroscopy and visual inspection. Statistical tests (Kruskal–Wallis and Mann–Whitney) showed no significant SBS differences among adhesives under identical conditions (p > 0.05). However, all adhesives exhibited significantly reduced SBS under saliva contamination (p < 0.001; T: 5.4 vs. 4.1 MPa; M: 5.7 vs. 3.6 MPa; S: 5.5 vs. 4.5 MPa). In dry conditions, SBS was significantly higher with 45° debonding (p < 0.05). Under contamination, SBS varied by ARI score (p = 0.05), with ARI 0 specimens showing higher SBS than ARI 3. These findings confirm that moisture reduces bond strength across adhesive types, while 45° force application enhances SBS under dry conditions. ARI score variability under contamination may reflect complex failure modes. Full article

The inner spacer module, which profoundly affects the final performance of a device, is a critical component in GAA NSFET (Gate-all-around Nanosheet Field Effect Transistor) manufacturing and necessitates systematic optimization and fundamental innovation. This work aims to develop an advanced SiGe etching process with high selectivity, uniformity and low damage to achieve an ideal inner spacer structure for logic GAA NSFETs. For three distinct dry etching technologies, ICP (Inductively Coupled Plasma Technology), RPS (Remote Plasma Source) and Gas Etching, we evaluated their potential and comparative advantages for inner spacer cavity etching under the same experimental conditions. The experimental results demonstrated that Gas Etching technology possesses the uniquely high selectivity of the SiGe sacrificial layer, making it the most suitable approach for inner spacer cavity etching to reduce Si nanosheet damage. Based on the results, in the stacked structures, the SiGe/Si selectivity ratio exhibited in Gas Etching is ~9 times higher than ICP and ~2 times higher than RPS. Through systematic optimization of pre-clean conditions, temperature and chamber pressure control, we successfully achieved a remarkable performance target of cavity etching: the average SiGe/Si etching selectivity is ~56, the inner spacer shape index is 0.92 and the local etching distance variation is only 0.65 nm across different layers. These findings provide valuable guidance for equipment selection in highly selective SiGe etching and offer critical insights into key process module development for GAA NSFETs. Full article