Silicon最新文献

In the present study, we investigate how varying annealing temperatures affect the structural, morphological, and optical properties of copper-titanium oxide composite films deposited on quartz substrates. A range of characterization techniques, including X-ray diffraction, Raman spectroscopy, scanning electron microscopy, atomic force microscopy, and UV–Vis spectroscopy, were employed to analyze the changes in film characteristics. The results demonstrate that annealing temperature plays a critical role in determining the film’s structural integrity, surface morphology, and optical behavior. The crystallite size increased from 16.97 nm at 500 °C to 68.07 nm at 900 °C, while surface roughness rose significantly, reaching 148 nm at 1000 °C. In addition, SEM analysis showed that particle size expanded from 12.55 nm at 400 °C to 603.60 nm at 900 °C. Notably, a strong relationship was found between film transparency and these physical properties, with optical transmittance decreasing from approximately 69% at 400 °C to around 2% at 1000 °C. Based on the findings, the study proposes optimal annealing conditions for achieving high-quality thin films.

Fe-Si alloy is an important soft magnetic alloy material in industrial production. Fe-Si alloy must be decarburized in the production process. Decarburization can not only improve the magnetic properties of the alloy itself, but also improve the corrosion resistance and processing performance of the alloy. The essence of decarburization is the diffusion of C atoms in the Fe-Si alloy. Therefore, it is very significant to study the diffusion process of C atoms in Fe-Si alloy. In this paper, the influence of Si content on the diffusion of C atoms is studied by first-principles. The interaction between C atoms and Si, the properties of bonding electrons in Fe-Si alloy and the diffusion barrier of C atoms are obtained. At the same time, the linear relationship between the diffusion barrier of C atom and Si content was obtained when the Si content was 1.56 at.% ~ 5.47 at.%. Through this linear relationship, the relationship between the diffusion coefficient of C atom and Si content and temperature is also obtained. Finally, the diffusion constant, diffusion coefficient and diffusion activation energy of C atoms in Fe-Si alloy were obtained by expression calculation, and the influence of Si content and temperature on the diffusion process of C atoms was quantitatively analyzed.

This study examines the effect of acidic versus alkaline saw damage removal (SDR) processes on the silicon surface morphology, interface electronic properties, and performance of silicon heterojunction (SHJ) solar cells, without employing any additional additives during SDR. Acidic SDR, using a simple mixture of HF, HNO₃, and CH₃COOH, produced uniformly etched surfaces that led to well-defined pyramid structures after alkaline texturization. This improved morphology enhanced surface passivation, resulting in a higher effective minority carrier lifetime of ~ 2.0 ms from ~ 1.2 ms and a reduction in the c-Si/a-Si:H interface defect density (D_it) to ~ 1.16 × 10⁹ from ~ 2.1 × 10⁹ cm⁻² eV⁻¹ compared to alkaline SDR. SHJ solar cells fabricated with the acidic SDR approach achieved superior performance, with a power conversion efficiency of ~ 22.0%, open-circuit voltage of ~ 733 mV, and fill factor of ~ 77.72%, outperforming those using alkaline SDR, having ~ 20.5%, ~ 730 mV, and ~ 76.04%, respectively. These findings demonstrate that even in the absence of chemical additives, acidic SDR effectively improves wafer surface morphology and device performance, offering an efficient approach for SHJ solar cell fabrication.

The Czochralski (CZ) method is a vital technique for producing single-crystal silicon, which is the foundation of high-efficiency solar panels for renewable energy applications. However, complex melt flow dynamics and impurity transport to the crystal growth interface can lead to defects in the silicon ingot, affecting the performance of solar cells. To address these challenges, external magnetic fields are employed to control melt flow and impurity distribution. In present study, a 3D magnetohydrodynamic (MHD) mixed convection model for the CZ crystal growth process is adopted. The numerical simulations are presented for various Hartmann numbers under transverse magnetic field (TMF) and cusp magnetic field (CMF) configurations, with fixed Richardson number and Reynolds number. The melt oscillation, flow structure, and oxygen concentration under TMF and CMF configurations are compared. CMF exerts a stronger suppression of the melt fluctuation than TMF configuration at the same Hartmann number around crucible bottom area. A periodic flow behavior is observed under CMF at Ha = 20. For TMF configuration, the damping effect due to Lorentz force is mainly exhibited on locations perpendicular to the magnetic field, which causes an un-axisymmetric temperature and velocity field. Oxygen concentration under CMF is significantly reduced compared with TMF cases. An elliptical shape oxygen radial distribution is observed under TMF, and forms a (theta ) angle with direction perpendicular to the magnetic field. Additionally, a uniform radial distribution is observed in central crystal region at high Hartmann number TMF cases. This research provides valuable insights into optimizing the CZ process for producing high-purity single-crystal silicon under magnetic field approaches, thereby enhancing the performance and reliability of single crystal silicon wafers for photovoltaic and semiconductor applications.

Dimethyldichlorosilane, an essential monomer in organosilicon synthesis, is often referred to as the "industrial monosodium glutamate". Traditional direct synthesis methods generate substantial by-products compromising the purity of dimethyldichlorosilane products, while disproportionation reactions enable the conversion of these by-products into the target compound. The catalytic mechanisms governing dimethyldichlorosilane disproportionation over both the pristine ZSM-5(8 T)@NH₂-MIL-53(Al) framework and its AlCl₃-functionalized derivative were computationally elucidated through M06-2X/def2-TZVP density functional theory (DFT) calculations, employing the Minnesota series hybrid functional protocol. Structural optimizations were performed on the molecular models followed by energy and vibrational frequency calculations. Comprehensive analytical methodologies encompassing bond order analysis, Electron Localization Function (ELF), Intrinsic Reaction Coordinate (IRC) tracking, and Localized Orbital Locator (LOL) revealed that the core–shell catalyst architecture incorporating Lewis acidic AlCl₃ exhibited significantly enhanced performance in the disproportionation reaction.

Silicon nanowires (SiNWs) were fabricated by electroless etching of n-type Si (100) wafer in HF/AgNO₃. High-density, vertically stacked silicon nanowires are formed on silicon substrates. The paper also discusses nanostructures in solar cells and compares several potential technologies for improving photovoltaic performance. The maximum recorded reflectance of silicon nanowires is about 19.2%, which is much lower than that of silicon substrate (65.1%). Through the results, in the near-ultraviolet region, the minimum reflection reaches about 3.5%, while in the visible infrared region it reaches 9.8%. It was also found that the calculated band gap energy of silicon nanowires is slightly higher than the energy of the silicon substrate The I–V characteristics of the independent silicon nanowires exhibit a linear ohmic behavior for forward bias. The average resistance of silicon nanowires is about 12.9 Ω cm. Using experimental reflectance spectra, the optical properties of different types of conical silicon nanowires (SiNWs) were investigated and the effective refractive index (n) was obtained for both the conical silicon nanowire samples and the silicon nanowire group. Under AM 1.5G illumination, the device exhibits a short circuit current density (Jsc) of 13.4 mA/cm², an open circuit voltage (Voc) of 0.479 V and a fill factor (FF) of 43.4%, giving a power conversion efficiency of 2.89%. The observed Jsc is higher than that of the control device with planar Si p–n junction, indicating a significant improvement in carrier generation and collection efficiency of the palanr structure. The effect of series resistance (Rs) was also studied.

In this study, the effects of silicon carbide (SiC) addition on the properties of cement mortars subjected to hydrochloric acid (HCl) exposure were evaluated. The primary objective was to assess the mechanical performance and durability enhancement of cement mortars incorporating SiC under aggressive acidic conditions. Cement mortars were prepared by replacing aggregates with SiC at ratios of 0%, 5%, 10%, and 15%, and were exposed to 10% HCl solution under three distinct environmental conditions: continuous immersion in acid, alternating periods in air, and water exposure. To evaluate acid resistance, the mass and compressive strength losses of the mortar specimens were measured before and after acid exposure. Additionally, micro-computed tomography (micro-CT) was conducted to examine internal microstructural changes. Results from mechanical tests and micro-CT analysis revealed that the incorporation of SiC significantly reduced the degradation of the cement matrix by densifying the microstructure and lowering porosity, thereby enhancing resistance to acid attack. These findings suggest that SiC can serve as an effective additive for improving the durability of cementitious materials in acidic environments.

Conventional methods of blood glucose monitoring typically require finger pricking to obtain a blood sample, which can be both painful and uncomfortable. Additionally, environmental factors can impact the accuracy and performance of glucose meters and test strips of diabetic patients. We introduce a novel non-invasive lab-on-chip device with an ultra-high sensitivity for routine blood sugar monitoring in diabetic patients, utilizing a patient's tear instead of blood samples to avoid daily unpleasant tests. The proposed sensor leverages the ultra-high sensitivity of the Mach–Zehnder interferometer and the linear response of the Microring resonator, which takes advantage of hybrid single and double-slot optimized waveguides. By employing the delay line signal approach and the Z-transform, a formula was developed to survey the system's overall transmittance. The results were simulated using the variational FDTD method, and an ultra-high sensitivity of 1092 nm/RIU with a high detection precision of 1.8 × 10⁻⁵ RIU was achieved using varFDTD simulation for the sensor. Results simulated for various concentrations of tears and can rapidly differentiate between diabetic and normal tears. The proposed sensor has various advantages, including a quick and painless detection procedure, high precision, and a wide performance range, all of which are desirable in an ideal lab-on-a-chip device.

In this study, a Double Gate (DG) Junction Less (JL) Vertical Tunnel FET(VTFET) structure with GaAs as Channel material is designed with catalytic metals as gate contacts and analyzed using Silvaco ATLAS TCAD simulation software for ammonia gas sensing. The vertical double-sided gate architecture provides better gate controllability over conventional TFETs for band-to-band tunneling (BTBT). Here GaAs is introduced in the channel which improves device sensitivity performance because of its rich physics like high electron mobility, and high band gap compared to more conventional semiconductor Silicon. P + pockets are created near the source region by using work function values and n-type doping of 1 × 10¹⁹ cm⁻³ is used in the channel region. The n-channel JL VTFET with Cobalt (Co) and Molybdenum (Mo) metals as gate contacts are analyzed for ammonia gas sensing. Characteristics of the proposed device structure are studied considering the electric field, surface potential, energy band diagram, and I_d-V_g characteristics curves by taking into account the adsorption of gas molecules. Due to the presence of gas on the gate metal, the work function changes which varies the Off-current (I_off), On-current (I_on), and threshold voltage (V_th) as these are considered as sensitivity parameters for sensing ammonia gas molecules. The length of the channel and the dielectric materials are also varied to see the change in sensitivities of the device. While comparing Silicon and GaAs-based DG JL VTFET gas sensor the simulation results demonstrate that the sensitivity, on/off current ratio of the GaAs-based device increases by varying the work function of catalytic metal gates cobalt and molybdenum by 50, 100, 150, and 200 meV.