Search Results (1,628)

In this study, high-conductivity W-doped Ga₂O₃ thin films were successfully fabricated by directly depositing a composition of Ga₂O₃ with 10.7 at% WO₃ (W:Ga = 12:100) using electron beam evaporation. The resulting thin films were found to be amorphous. Due to the ohmic contact behavior observed between the W-doped Ga₂O₃ film and platinum (Pt), Pt was used as the contact electrode. Current-voltage (J-V) measurements of the W-doped Ga₂O₃ thin films demonstrated that the samples exhibited significant current density even without any post-deposition annealing treatment. To further validate the excellent charge transport characteristics, Hall effect measurements were conducted. Compared to undoped Ga₂O₃ thin films, which showed non-conductive characteristics, the W-doped thin films showed an increased carrier concentration and enhanced electron mobility, along with a substantial decrease in resistivity. The measured Hall coefficient of the W-doped Ga₂O₃ thin films was negative, indicating that these thin films were n-type semiconductors. Energy-Dispersive X-ray Spectroscopy was employed to verify the elemental ratios of Ga, O, and W in the W-doped Ga₂O₃ thin films, while X-ray photoelectron spectroscopy analysis further confirmed these ratios and demonstrated their variation with the depth of the deposited thin films. Furthermore, the W-doped Ga₂O₃ thin films were deposited onto both p-type and heavily doped p⁺-type silicon (Si) substrates to fabricate heterojunction diodes. All resulting devices exhibited good rectifying behavior, highlighting the promising potential of W-doped Ga₂O₃ thin films for use in rectifying electronic components. Full article

The energy deposition process for the main components of SIC Schottky diodes is simulated based on Geant4. Particle bombardment results were simulated under different angles, target materials and doping concentrations on the same target material for different light particles and heavy ions, and then the Linear Energy Transfer of SiC materials and external conditions that affect LET are obtained. The results show that the LET value of protons exhibits significant oscillations at low energy incidence, gradually decreasing exponentially after 10⁻¹ MeV. Alpha particles have a LET peak near 1 MeV, while beta particles show an exponential decrease. The LET values at low energy levels increase exponentially, while at high energy levels, the LET values show a similar linear relationship with energy. For different incident angles, the average LET value of protons in the low-level region gradually increases as the incident angle increases. The average LET value of protons in the remaining energy ranges is less affected by angle; the incident angle has no significant effect on the LET distribution of alpha particles within the full spectrum range. The results provide important references for understanding the energy deposition process and LET distribution of silicon carbide devices under single-particle interaction. Full article

This work presents a novel Gallium Nitride (GaN) high-electron-mobility transistor (HEMT)-based ultraviolet (UV) photodetector architecture that integrates advanced material and structural design strategies to enhance detection performance and stability under room-temperature operation. This study is conducted as a fully numerical simulation using the Silvaco Atlas platform, providing detailed electrothermal and optoelectronic analysis of the proposed device. The device is constructed on a high-thermal-conductivity silicon carbide (SiC) substrate and incorporates an n-GaN buffer, an indium nitride (InN) channel layer for improved electron mobility and two-dimensional electron gas (2DEG) confinement, and a dual-passivation scheme combining silicon nitride (SiN) and hexagonal boron nitride (h-BN). A p-GaN layer is embedded between the passivation interfaces to deplete the 2DEG in dark conditions. In the device architecture, the metal contacts consist of a 2 nm Nickel (Ni) adhesion layer followed by Gold (Au), employed as source and drain electrodes, while a recessed gate embedded within the substrate ensures improved electric field control and effective noise suppression. Numerical simulations demonstrate that the integration of a hexagonal boron nitride (h-BN) interlayer within the dual passivation stack effectively suppresses the gate leakage current from the typical literature values of the order of ${10}^{-8}$ A to approximately ${10}^{-10}$ A, highlighting its critical role in enhancing interfacial insulation. In addition, consistent with previous reports, the use of a SiC substrate offers significantly improved thermal management over sapphire, enabling more stable operation under UV illumination. The device demonstrates strong photoresponse under 360 nm ultraviolet (UV) illumination, a high photo-to-dark current ratio (PDCR) found at approximately ${10}^6$, and tunable performance via structural optimization of p-GaN width between 0.40 μm and 1.60 μm, doping concentration from $5\times {10}^{16}$ ${\mathrm{cm}}^{-3}$ to $5\times {10}^{18}$ ${\mathrm{cm}}^{-3}$, and embedding depth between 0.060 μm and 0.068 μm. The results underscore the proposed structure’s notable effectiveness in passivation quality, suppression of gate leakage, and thermal management, collectively establishing it as a robust and reliable platform for next-generation UV photodetectors operating under harsh environmental conditions. Full article

Background/Objectives: Fluoride ion plays a crucial role in protecting teeth against caries by re-mineralizing the caries lesion. The objective of this study was to quantify and compare the fluoride release and recharge of restorative dental materials and their correlation with mass stability. Methods: For this study, 5 × 5 × 2 mm blocks were prepared from GIC, RMGI L, GIOMER, Resin Composite, and RMGI R using a customized silicone index. The amount of fluoride released from each material was quantified using a fluoride electrode at 0 h, 1 day, 3 days, 1-week, and 2-week periods. The fluoride recharge of each material was calculated by quantifying the amount of fluoride uptake from high concentration fluoride solution over a period of 1-week. The mass stability of the materials was measured be quantifying the weight loss/weight gain during fluoride release and recharge phase. The correlation of fluoride release/recharge with weight loss/gain were analyzed using Pearson correlation. Results: One-way ANOVA showed a statistically significant difference in the amount of fluoride released from each group (p < 0.05). The maximum amount of fluoride release was observed on the 3rd day in all the groups except the GIC group, which showed an ascending concentration of fluoride release till 2 weeks. One-way ANOVA showed statistically significant differences in weight loss/gain among the rested group (p < 0.05). GIC showed the highest amount of weight loss and weight gain among the tested materials. Conclusions: The GIC material has the highest fluoride release and RMGI L has the highest fluoride recharge capability. The conventional GIC showed the least mass stability during fluoride release/recharge. Full article

The dye-sensitized solar cell (DSSC) is a promising candidate, offering an attractive substitute for conventional silicon-based photovoltaic technologies. The performance advantages of the DSSC have led to a surge in research activity reflected in the number of publications over the years. To deliver data-driven analysis of DSSC performance, machine learning models have been applied. As a first step, a literature-based database has been developed and after the data preprocesses, Decision Tree (DT), Random Forest (RF), K-Nearest Neighbors (KNN), Support Vector Machine (SVM), xgboost (XGB), and Artificial Neural Network (ANN) algorithms were applied with stratified train-test splits. The performance of the models has been assessed via metrics, and the model interpretability relied on SHAP analysis. Based on the employed metrics and the confusion matrix, DT, RF, and KNN are the most accurate models for predicting DSSC efficiency on the developed dataset. Furthermore, it was revealed that synthesis temperature and the thickness of thin film were identified as the dominant drivers, followed by precursor and dye. Mid-tier contributors were morphological structure, electrolyte concentrations, and the absorption maximum. The results suggest that in optimizing the manufacturing process, targeted tuning of the synthesis temperature, the thickness of thin film, the precursor, and the dye are likely to improve the performance of the device. Therefore, experimental effort should concentrate on these factors. Full article

The Hugushan banded iron formation (BIF) is one of the most representative iron ore deposits in the central part of the North China Craton, and its ore formation mechanism remains highly controversial. This study presents whole-rock and Fe–Si–O isotope geochemical evidence, offering a new perspective on the ore formation mechanism of the Hugushan BIFs. The samples from the upper and lower parts of the Hugushan BIFs are characterized by slight enrichment of heavy and light Fe isotopes, respectively. Additionally, the samples from the upper part of the Hugushan BIFs show characteristics of slightly positive Ce anomalies and negative La anomalies, suggesting that the shallow ancient seawater was in a partially oxidized state, whereas the deep seawater remained in a reductive environment during the depositional period. The low Al₂O₃ and TiO₂ concentrations, as well as the depletion of Zr and Hf in the Hugushan BIFs, suggest that the contribution of terrestrial detrital materials to deposition is extremely limited. The BIFs all exhibit positive Eu anomalies, and the quartz in the BIFs is depleted in ³⁰Si, a characteristic similar to that observed in siliceous rocks formed in hydrothermal vent environments and during hydrothermal plume activity. Additionally, the δ¹⁸O values of quartz in Hugushan BIFs are similar to the O isotope compositions of hydrothermal sedimentary siliceous rocks, further suggesting that the silicon in BIFs originates primarily from seafloor hydrothermal activity. The combination of Eu/Sm, Sm/Yb, and Y/Ho ratios indicates that the major components (iron and silica) of the Hugushan Iron Ore Deposit originated from the mixing of high-temperature hydrothermal fluids with seawater, with the hydrothermal fluid contributing slightly less than 0.1%. The magnetite and quartz bands in the BIFs exhibit inhomogeneous and covariant δ⁵⁶Fe and δ³⁰Si isotope characteristics, suggesting that the alternating siliceous and ferruginous layers are products of original chemical deposition in the ocean. Periodic hydrothermal activity and ocean transgression caused the recurring deposition of siliceous and ferruginous layers, resulting in the characteristic banded structure of the Hugushan Iron Ore Deposit. Full article

This study evaluated the effect of polyethylene glycol (PEG 1500 and 4000) addition on the enzymatic hydrolysis (EH) of ground rice husk (≤250 μm). To reduce the amount of enzyme adsorbed on silicon dioxide and lignin and to evaluate the enzymatic hydrolysis, PEG 1500 and 4000 g/mol were added at three concentrations (0.3, 0.4 and 0.5 g PEG/g SiO₂). When PEG 1500 was added at 0.5 g/g SiO₂, the conversion of cellulose to cellobiose was not significantly increased (p ≥ 0.05); the conversion to glucose was 41.76%, and the conversion of hemicellulose to xylose was 93.45%, all with respect to the control assay. Addition of PEG 4000 at 0.5 g/g SiO₂ showed an increase of 14.78% in the hydrolysis of cellulose to cellobiose, 56.59% in that of cellulose to glucose, and 93.24% in that of hemicellulose to xylose. The addition of PEG shows that at a higher molecular weight and higher concentration, there are significant differences in the percentage of conversion of cellulose and hemicellulose into fermentable sugars, achieving efficiencies of ≈75%. Full article

In optical one-dimensional grating-on-layer planar structures, an optical resonance occurs when the incident light wave becomes phase-matched to a leaky waveguide mode excited in the layer underneath the grating by an appropriate tuning of the grating periodicity. Changing the refractive indices of the grating’s constituents, and/or thickness, changes the resonance frequency. In the case of a two-dimensional grating atop such a smooth layer, a similar and also cavity-mode resonance can occur. This idea has straightforward usage in diverse optical sensor applications. In this study, a novel guided-mode resonance sensor design for detecting glucose and hemoglobin in minute concentrations at a wide range of incidence angles is presented. In this design, materials of the grating, such as a polymer and cesium-lead halide with a perovskite crystal structure, are examined, which will allow flexible, low-cost fabrication by soft-lithography/imprint-lithography methods. The sensitivity, figure of merit, and quality factor are reported for one- and two-dimensional grating structures. The simulations performed are based on rigorous coupled-wave analysis. Optical resonance quality factor of ∼$5·{10}^5$ is achieved at oblique incidence for a structure comprising a one-dimensional grating etched in a poly-vinylidene chloride layer atop a silicon nitride waveguide layer on a substrate. Record values of the above-noted characteristics are achieved with a synergetic interplay of the materials, structural dimensions, incidence angle, polarization, and grating geometry. Full article

This study investigates the potential of two low-iron-grade bauxite residue (BR) samples, containing up to 27.4 wt.% Fe and originating from alumina plants in Romania and Turkey, for the recovery of iron concentrate via wet magnetic separation. The methodology involved the hydrothermal reduction of the residues, aiming to transform the hematite/goethite (Fe³⁺) phases into magnetite (Fe²⁺/Fe³⁺) and enhance their magnetic susceptibility. The effect of hydrothermal treatment, magnetic induction value (up to 1600 Gs), and slurry dispersion on iron recovery and iron grade were investigated. An optimum magnetic fraction was obtained, containing 44.4 wt.% elemental iron (Fe_elem) and achieving 98% iron recovery. These results demonstrate a significant improvement compared to the magnetic fraction derived from the respective non-reduced sample, which showed a maximum of 29.7 wt.% Fe grade and 59.7% recovery. Furthermore, silicon and sodium are primarily distributed in the non-ferrous fraction. The application of sonication to enhance slurry dispersion during magnetic separation did not have a positive impact on the process. In addition to iron recovery, an aspect of considerable potential is the reutilization of the Al-rich liquor generated during hydrothermal treatment of the BR. Its reintroduction into the Bayer process circuit could contribute to improved material utilization and enhanced overall process efficiency. Full article

The reaction tank of process wastewater, as one of the key pieces of equipment for wastewater treatment, is exposed to an acidic and alkaline wastewater immersion environment for a long time and is prone to the influence of complex ions in water, resulting in concrete shedding and steel bar corrosion, which seriously affect service performance. To address the issue of ionic erosion in process wastewater reaction tanks, a silicon–oxygen grid substrate was constructed with ethyl orthosilicate, and graphene oxide was used as the corrosion-resistant functional component to prepare GO/SiO₂ corrosion-resistant films under acid-catalyzed conditions. Extreme corrosion environments were designed to evaluate the corrosion resistance of GO/SiO₂ films. The results showed that the permeability of the uncoated samples decreased significantly, and the ion concentration leached in the corrosive medium was higher. The permeability of the GO/SiO₂-coated samples did not decrease significantly, and the ion leaching concentration in the corrosive medium gradually decreased with the increase in GO content, verifying the positive correlation between GO content and corrosion resistance and GO’s use in the field of corrosion resistance in water treatment facilities. Full article

Trap states in 2D transition metal dichalcogenides significantly affect the responsivity and response time of photodetectors, and previous ReS₂/Si-based heterojunction photodetectors have struggled to simultaneously achieve high responsivity and fast response. To address this issue, we developed a n-type ReS₂/p-type Si heterojunction photodetector through interface engineering. Specifically, the silicon substrate with a silicon dioxide dielectric layer was treated with inductively coupled soft plasma to adjust the thickness and surface states of the dielectric layer. This treatment created a multilayered heterostructure, which increased carrier concentration, effectively passivated sulfur-vacancy-induced defects, and thereby improved responsivity. Experimental results showed that the silicon-based n-type ReS₂ photodetector achieved a responsivity of 0.88 A W⁻¹ with a rapid response rise time of 2.5 s, a significant improvement from the intrinsic values of 12 mA W⁻¹ responsivity and 6 s rise time. Additionally, due to the defect-tunable nature of this pretreatment technique, the device exhibited enhanced Raman peaks and intensified photoluminescence (PL) absorption features, confirming the effectiveness of the interface engineering in optimizing device performance. Full article

Using molecular dynamics (MDs) simulations with Materials Studio 8.0 software, we systematically investigated the adsorption and aggregation behaviors of silicon, tin, and copper atoms on the surface of (7,7) single-walled carbon nanotubes (SWCNTs). Silicon, tin, and copper were selected due to their distinct bonding characteristics—covalent (Si), semi-metallic (Sn), and metallic (Cu)—and their relevance in potential composite interface applications such as energy storage, thermal management, and electronics. The results indicate that silicon atoms form multi-layered concentric shells; however, the rigidity of their covalent bonds makes the resulting structures susceptible to disruption by local density fluctuations. Tin atoms form a limited number of stable concentric shells benefiting from the flexibility of their semi-metallic bonds. In contrast, copper atoms rapidly aggregate into disordered clusters due to their high diffusivity and metallic bonding. Within the confined geometry of the carbon nanotubes, all three types of atoms exhibit a tendency toward spiral growth, but their regularity depends on the properties of their chemical bonds, leading to distinct spiral features. These findings are further supported by linear density and radial distribution function (RDF) analyses. Full article

The present study provided an exhaustive examination of VOC emissions originating from 13 different raw materials susceptible to being used in the sampling of the human volatilome and encompassing both polymeric and non-polymeric compositions. To achieve this aim, thermodesorption coupled with comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (TD-GC×GC/ToFMS) was employed. For each material, we report the total number of detected peaks, total volatile organic compound (TVOC) concentration, distribution of VOC emissions across different chemical families, minimum and maximum individual concentrations, as well as hypotheses regarding the origins of some specific VOCs depending on the material considered. The findings from this investigation revealed that materials, such as silicone and polyurethane, could emit an extensive array of VOCs, with up to 2000 chromatographic peaks detected, and emissions of total volatile organic compounds (TVOCs) reaching levels of 5.4 µg·g⁻¹ and 9.8 µg·g⁻¹, respectively. In the case of polyamide, some VOCs could be related to potential reagents involved in its synthesis. While highlighting materials that should be used with caution depending on the topic and target analytes, this study identified materials that exhibited minimal VOC emissions, such as polytetrafluoroethylene, aluminum, and stainless steel, after an adequate conditioning step. The selected analytical technique, TD-GC×GC/ToFMS, proved its relevance to identify and characterize semi-quantitatively VOC emissions coming from those materials. Such information was essential within the frame of the development of a body odor sampling system, our primary objective. Full article

This study investigates the novel application of silicon nanoparticles (SiO₂ NPs) to enhance drought tolerance and medicinal quality in the threatened medicinal plant Sophora tonkinensis, providing technical support for its conservation and cultivation. Six treatments were applied: control (CK), CK + 100 mg/L SiO₂ NPs, CK + 200 mg/L SiO₂ NPs, drought stress (SD), SD + 100 mg/L SiO₂ NPs, SD + 200 mg/L SiO₂ NPs. After 21 days of foliar application, we assessed biomass, physio–biochemical parameters (including soluble protein, soluble sugar, superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), malondialdehyde (MDA), superoxide anion (O₂⁻), and hydrogen peroxide (H₂O₂)), as well as concentrations of matrine, oxymatrine, genistin, genistein, total alkaloids, and total flavonoids. Under drought stress, the application of 100 mg/L SiO₂ NPs was the most effective treatment for enhancing biomass accumulation and eliciting a coordinated physio–biochemical response. This was demonstrated by a significant increase in leaf soluble protein content and root SOD activity, along with a decrease in oxidative stress markers (H₂O₂ and O₂⁻). Furthermore, SiO₂ NPs application under both normal and drought conditions selectively enhanced the accumulation of bioactive compounds in the roots, with the optimal concentration being compound-specific. Notably, under drought conditions, the application of 200 mg/L SiO₂ NPs proved optimal for enhancing the biosynthesis of several key medicinal compounds in the roots. Specifically, this treatment significantly maximized the content of matrine (214.15 μg/g), genistin (4.06 μg/g), genistein (48.56 μg/g), total alkaloids (9.96 mg/g), and total flavonoids (11.44 mg/g) compared to the drought-stressed control (SD). These results demonstrate that SiO₂ NPs significantly improve yield and key medicinal components of S. tonkinensis under drought stress, with a differential efficiency depending on the concentration, plant organ, and target compound. Full article

Silicon-based MEMS devices are essential in extreme radiation environments but suffer progressive reliability degradation from irradiation-induced defects. Here, the generation, aggregation, and clustering of defects in single-crystal silicon were systematically investigated through molecular dynamics (MD) simulations via employing a hybrid Tersoff–ZBL potential that was validated by nanoindentation and transmission electron microscopy. The influences of the primary knock-on atom energy, temperature, and pre-strain state on defect evolution were quantified in detail. Frenkel defects were found to cause a linear reduction in the Young’s modulus and a nonlinear decline in thermal conductivity via enhanced phonon scattering. To link atomic-scale damage with device-level performance, MD-predicted modulus degradation was incorporated into finite element (FE) models of a sensing diaphragm. The FE analysis revealed that modulus reductions result in nonlinear increases in deflection and stress concentration, potentially impairing sensing accuracy. This integrated MD–FE framework establishes a robust, physics-based approach for predicting and mitigating irradiation damage in silicon-based MEMS operating in extreme environments. Full article