Silicon最新文献

Purpose

Accurate dosimetry in small photon fields is a significant challenge in clinical radiotherapy due to detector limitations and complex physical phenomena. This study evaluates the performance of the microSilicon diode detector in small field dosimetry by comparing it with the microDiamond type 60,019 detector and Gafchromic EBT3 film as the reference.

Methods

Measurements were conducted using a 6 MV photon beam from a Clinac IX linear accelerator. Comparative analysis was based on Percentage Depth Dose (PDD), dose profiles (DP), and Output Factor (OF) measurements, with the Relative Dose Difference (RDD) method used for quantitative assessment.

Results

A calibration curve for EBT3 film was established for doses ranging from 0 to 360.9 cGy, achieving a mean deviation of ± 0.5%. PDD measurements showed close agreement between microSilicon and microDiamond detectors for field sizes > 10 × 10 mm², with RDD < 1.2%. For the 5 × 5 mm² field, microSilicon exhibited greater accuracy, with an average RDD of 1.8% compared to 2.5% for microDiamond. Dose profile measurements revealed that microSilicon provided sharper penumbra widths, particularly in high-dose gradient regions, with RDD < 1.5% compared to EBT3 film. OF measurements demonstrated consistency between microSilicon and microDiamond for fields > 10 × 10 mm², with RDD < 1.0%. However, for the 5 × 5 mm² field, microSilicon outperformed microDiamond, showing an RDD of 2.1% versus 3.4%.

Conclusion

These results highlight the microSilicon detector’s superior performance in small field dosimetry, attributed to its reduced sensitive volume and optimized encapsulation layer, making it a promising tool for stereotactic radiotherapy applications.

A low-cost, easy-to-prepare multilayered Surface Enhanced Raman Scattering (SERS) plasmonic sensor was developed with a trimetallic pattern consisting of Aluminum nanostructures (AlNSs), Copper nanostructures (CuNSs), and Palladium nanostructures (PdNSs) on the surface of porous silicon (PSi). PSi was fabricated using the Photo-Electro-Chemical-Etching (PECE) method. Immersion plating was used to deposit the (1:1:1) (Al: Cu: Pd) trimetallic mixed solution on the surface of PSi to fabricate the trimetallic Al/Cu/Pd/PSi SERS sensor. The fabricated sensor was tested with various concentrations of Potassium nitrate (KNO₃).Field Emission Scanning Electron Microscope (FE-SEM) measurements showed a unique cauliflower-like structure which is ideal for SERS applications. Energy Dispersive Spectroscopy (EDS) confirmed the presence of the metals, while X-ray Diffraction (XRD) investigated the crystallinity of this structure. Raman results indicated that the sensor’s performance was influenced by the surface density and arrangement of metal nanostructures (NSs). The sensor exhibited high enhancement factor (EF) of (1.91 × 10¹²) with low limit of detection (LOD) of (3.19 × 10^–10) M. The specifications of this trimetallic Al/Cu/Pd/PSi SERS sensor such as high surface area and dense hot spot regions enabled efficient energy transfer, enhancing its ability to detect ultra-low nitrate concentrations below allowable limits. Our results showed high stability and detection sensitivity demonstrating promising potential for rapid detection and on-site analysis.

A novel benzimidazole derivative, 1-(4-chlorobenzyl)-2-(4-chlorophenyl)-4-fluoro-1H-benzo[d]imidazole (CCHFB), was synthesized via a three-component condensation reaction involving 3-fluorobenzene-1,2-diamine, 5-chloro-2-hydroxybenzaldehyde, and ammonium acetate in the presence of ZnO nanoparticles as a catalyst. The synthesized compound was further functionalized with SiO₂ nanoparticles to investigate enhancements in physicochemical and biological properties. Comprehensive spectral analyses including UV–Vis, fluorescence, NMR, and FT-IR confirmed successful functionalization and highlighted the molecular interactions between CCHFB and the nanoparticle surface. UV–Vis spectra showed enhanced absorbance, while fluorescence quenching indicated possible electron transfer interactions. FT-IR analysis revealed shifts in azomethine group vibrations, confirming nanoparticle binding. Biological evaluations demonstrated that functionalized CCHFB exhibited notable antioxidant activity (via phosphomolybdenum and DPPH assays), significant α-amylase inhibitory potential, and enhanced antibacterial effects against both Gram-positive and Gram-negative strains, compared to unmodified CCHFB. Stability studies revealed that the functionalized compound retained over 92% structural integrity over 24 h in physiological buffer. These findings suggest that SiO₂-functionalized CCHFB is a promising candidate for pharmaceutical and biomedical applications due to its enhanced stability, bioactivity, and broad-spectrum antimicrobial properties.

Graphical Abstract

Gliomas are aggressive primary brain tumors with poor treatment outcomes due to their infiltrative nature and therapy resistance. To address this, we developed a targeted nanoplatform based on compound 1 (1), a bioactive molecule extracted from Momordica charantia (M. charantia), functionalized with 3-aminopropyltrimethoxysilane (APTMS) and D-glucosamine (GlcN) to yield GlcN-1-APTMS@CP1, and further loaded with quercetin (Qu) to form GlcN-1-APTMS@CP1@Quercetin. This system exhibited efficient drug loading (pore size reduced from 416.65 μm to 320.68 μm), pH/redox-responsive release, and strong fluorescence at 460 nm. It showed high selectivity for Fe³⁺ and glioma biomarkers, particularly Bcl-2 (K = 4.04 × 10⁴ M⁻¹, R² = 0.9941), with robust stability and anti-interference performance. In vitro, the platform effectively triggered glioma cell apoptosis via the Bcl-2/Bax pathway, highlighting its potential as a plant-derived, quercetin-loaded nanomedicine for glioma therapy.

The integration of Through Glass Vias (TGVs) and microfluidic systems into advanced materials such as silicon dioxide (SiO₂) glass has garnered significant attention owing to their exceptional thermal, chemical, and mechanical properties in various industrial applications, particularly in biomedical, bioelectronics, lab-on-chip devices etc. Electrochemical Discharge Machining (ECDM) has emerged as a promising hybrid micromachining technique for processing non-conductive materials. However, despite its advantages, the process faces several challenges, such as inadequate flushing, restricted electrolyte replenishment, and temperature variations, which collectively impact its overall machining efficiency. As a consequence, the current research work aims to strengthen the performance and enhancement of localised thermal effects and discharge stability to improve machining characteristics by incorporating tool rotation in the ECDM process, referred to as the rotary-mode ECDM process. The primary aim of this research is to systematically analyse the stimulus of key process input parameters such as rotational speed of tool electrode, gap between the electrodes (IEG), applied voltage, and concentration of electrolyte on machining performance metrics, including depth overcut, and surface roughness of the microchannels. The percentage reduction in surface roughness and depth overcut gained using rotary-mode compared to standard ECDM process was 28.5% and 42.4% respectively. The optimal input parameters were identified as 68 V voltage, 20 g/L electrolyte concentration, 30 mm IEG, and 500 rpm rotational speed. Additionally, the successful fabrication of Through Glass Vias (TGVs) with microchannel structure demonstrates the technique's potential for various industrial applications like 3D integrated circuits (3D ICs), MEMS devices, biochips, and lab-on-chip.

A vertical dopingless silicon tunnel field-effect transistor (VDL-SiTFET) is proposed and evaluated as a high-performance resistance temperature detector (RTD). This work is motivated by the need for compact, high-sensitivity, low noise temperature sensor capable of operating over a wide temperature range. We conducted comprehensive device simulations over a wide temperature range (50–500 K) using gate voltages from 0.5 V to 1.5 V in 0.25 V increments. The device exhibits a strong negative temperature coefficient of resistance of -25.7 (times ) 10(^4)/K, indicating a significant decrease in resistance with rising temperature. At a gate voltage of 0.5 V, the RTD response is highly linear (R(^{textbf {2}}) (varvec{approx }) 0.974), and the sensitivity reaches a peak of -300.6 (varvec{Omega })/K. These results confirm the proposed VDL-SiTFET’s high sensitivity and linear accuracy as a temperature sensor. Furthermore, the impact of positive and negative interface trap charges (ITCs) on device reliability is examined. Simulations reveal that ITCs slightly alter the temperature-dependent ON-state resistance, highlighting their critical role in ensuring sensor reliability. Overall, the proposed VDL-SiTFET shows promise as a highly linear, sensitive RTD, with careful consideration of interface traps necessary to ensure reliable operation in practical devices.

Rice husk ash (RHA), a silica-rich byproduct of rice milling, poses environmental and health risks due to the presence of heavy metals and particulate matter. This study presents an optimized biomass gasification method to extract high-purity silica from RHA for industrial applications. Rice husks were gasified at 810–860 °C to produce RHA, dissolved in 2 N NaOH at 105 °C for 2–3 h, followed by carbon removal and sulfuric acid precipitation to yield fine silica powder. The extraction process was optimized for RHA type, gasification duration, and dissolving time, with kinetic analysis using pseudo-first-order and pseudo-second-order models. XRD analysis confirms 96%-99% pure amorphous silica after 4 h of dissolving and 1 h of gasification. Extraction efficiencies were 73.33% and 86.66% by weight for fly and bottom ash, respectively. FTIR analysis confirmed the presence of Si–O-Si and Si–OH bonds. BET surface area analysis showed fly ash-derived silica with a higher surface area (412.72 m²/g) than bottom ash-derived silica (298.98 m²/g). Kinetic studies indicated a peak reaction rate at 2 h (43.33% yield, k₁ = 0.0179 h⁻¹, k₂ = 0.0088 g/(g·h)), with optimal yields between 3 and 4 h. This method provides a sustainable solution for RHA disposal. Future research should explore scalability and practical implementation.

Graphical Abstract

In this work, we investigate the effect of rapid thermal oxidation on the structural, optical, and electrical properties of p-Si nanowires (SiNWs)/SiO₂/n-ZnO heterojunction photodiodes. ZnO thin films were deposited via sputtering onto both planar and nanostructured silicon substrates. XRD and FTIR analyses confirmed the formation of a single-phase hexagonal wurtzite structure, while thermal oxidation led to the appearance of SiO₂-related signatures and modified the crystallographic orientation of ZnO. SEM observations revealed uniform ZnO coating on vertically aligned SiNWs, with grain sizes between 250 and 360 nm. Optical measurements highlighted the excellent light-trapping capability of SiNWs, despite a slight increase in reflectivity due to the SiO₂ layer. Electrical characterization demonstrated that oxidation at 900°C significantly enhances diode performance by reducing both series and dynamic resistances, indicating improved interface passivation. However, oxidation at 1000°C led to a moderate degradation in electrical parameters, likely due to excessive oxide growth. These results underline the potential of controlled thermal oxidation for tuning the properties and improving the performance of SiNWs-based heterojunction photodiodes for optoelectronic applications.

This work explores the synthesis of ZnO thin films through a straightforward co-precipitation method, with and without nickel (Ni) doping, followed by spin coating onto silicon (Si) substrates. The main objective is to investigate the effects of varying Ni doping concentrations on the structural, morphological, and opto-electronic characteristics of the resulting films. Analytical techniques including X-ray diffraction (XRD), atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FTIR), and optical reflectance measurements were used. FTIR and reflectance measurements were performed to assess the surface passivation properties of both Ni-doped and undoped ZnO films. Ni doping led to improved crystallinity, increased grain size, and the formation of Zn–O–Ni and Si–Zn bonds, enhancing the interface quality. Significantly, the minority carrier lifetime increased from 2 μs (undoped) to 82 μs at 2 at.% Ni doping, at a carrier density of 10¹⁴ cm⁻³. In parallel, the reflectance at 500 nm decreased from 31 to 5%, demonstrating the films’ effective antireflection behavior. These improvements underline the potential of Ni-doped ZnO as a dual-function passivation and antireflection layer for Si-based photovoltaic devices.

This work investigates oxidation-related quenching of the photoluminescence intensity of porous silicon produced from metallurgical-grade silicon powders, aiming to understand the mechanisms in this defect-rich material. The synthesis of porous silicon was performed by stain etching, but no catalyst was needed. It takes advantage of the inherent metallic impurities present in metallurgical-grade silicon to act as catalysts. The method is both scalable and cost-effective. By scanning electron microscopy, it was observed that etching created a porous layer on the surface of silicon grains, increasing the material's surface area by 200 times, as confirmed by BET adsorption isotherms. The photoluminescence spectra can be deconvoluted in three bands, which can be assigned to three main phenomena contributing to the emission: quantum confinement effects, oxidized silicon nanocrystals, and the presence of Si–H bonds. It has been found that the intensity of the photoluminescence spectrum decreases in proportion to the oxidation times of the porous silicon powders in hydrogen peroxide. They could be due to changes in the surface chemistry, replacing Si–H and Si–Si bonds with Si–OH and Si–O-Si bonds, as evidenced by Infrared spectroscopy ATR. The decay has been modeled mathematically, describing a first-order chemical reaction. The resulting equation could be used as a calibration curve to determine the amount of oxidant present in a solution if put in contact with the porous silicon. The results demonstrate the potential of photoluminescent porous silicon as a base material for developing low-cost optoelectronic devices and chemical sensors.

Graphical Abstract

Porous silicon powders synthesized from metallurgical grade silicon by stain etching present intense photoluminescence of about 685 nm. The total photoluminescence intensity decreases with chemical oxidation due to the competing effects of non-radiative Si–OH and radiative Si–O-Si. The present study provides valuable insights into the photoluminescent mechanisms of metallurgical-grade porous silicon.