Si Structures Research Articles

Low current driven blue-violet light-emitting diodes based on p-GaN/i-Ga2O3/n-Ga2O3:Si structure

This paper reports a low current driven LED with p-GaN/i-Ga2O3/n-Ga2O3:Si structure prepared by radio frequency (RF) magnetron sputtering, the driving current of the device is only 0.02 mA. Compared with the reported drive current of the LEDs, the reduction is 100 or even 1000 times. Through the study of its electrical properties, it was found that it had excellent rectification characteristics at different ambient temperatures and the turn-on voltage was about 1.8 V. In addition, the leakage current was as low as 4.30 × 10-8 mA. Through the electroluminescence test, it was found that the device had the function of emitting in the ultraviolet (363 nm) and visible (425 nm) region, which realized the blue-violet luminescence at room temperature. Furthermore, the device had excellent high temperature color stability and ultra-low color temperature of 1924 K. The color coordinate of the device at room temperature was (0.1905,0.0955). A detailed study was conducted on the electroluminescence mechanism of the device through its band structure, and the causes of the luminescence were analyzed through the Gaussian fitting of the EL spectrum.

Syntactic asymmetry and spillover effects in simultaneous interpreting with slides: an eye-tracking study on beginner interpreters

ABSTRACT Simultaneous interpreting with text or slides is a complex form of bilingual language processing due to its dual input. The present study seeks to explore the processing and rendering of asymmetrical structures in SI with slides. To achieve this, we first investigate asymmetrical structures in Chinese-English SI with slides in both directions. Then, we examine whether the processing of asymmetrical structures generates a spillover effect on the continuation segment, and how the spillover effect varies with the interpreting direction. Twenty interpreting students were invited to perform tasks of SI with slides in an eye-tracking experiment. The results show that (1) the processing of asymmetrical structures was more challenging in L2–L1 SI with slides than in L1–L2 SI with slides; (2) asymmetrical structures had a spillover effect on the processing of the subsequent segment; (3) the spillover effect was greater in L2–L1 than in L1–L2 SI with slides. The findings provide new insights into the processing of syntactic asymmetry in an interpreting mode with dual input. Our results also suggest that asymmetrical structures might be potential causes of the spillover effect.

Preparation and Properties of Translucent Suspension Chain Polyurethane With a Broad Damping Temperature Range at Near Room Temperature

ABSTRACTDeveloping a viscoelastic polymer damping material with a broad range of effective damping temperatures at room temperature and multiple functionalities has been a prominent research focus, possessing significant economic and social importance. Herein, the elastic main chain was synthesized using branched polyester polyol (DPH) and isophorone diisocyanate (IPDI). The suspension chain prepolymer was fabricated with monohydroxy long alkyl‐chain hydroxy silicone oil (OH‐PDMS) and IPDI. Translucent and damping branched polyurethane viscoelastic materials (BPUs) were prepared by reacting the elastic main chain and the suspension chain prepolymer with the cross‐linking agent trimethylolpropane (TMP). The influences of introducing suspension chains and their content within the polyurethane structure on the damping, mechanical, dynamic mechanical, thermomechanical, and water resistance properties of the polyurethane were comprehensively investigated. The experimental results indicate that the damping factor (Tanδmax) of polyurethane decreases from 1.17 to 0.91 with the addition of suspension chain. Then, with the increase of suspension chain content, the damping factor (Tanδmax) decreases slightly. The damping factor (Tanδmax) still reaches 0.84 with 66% suspension chain content. At the same time, the effective damping temperature range gradually increases from 56.4°C to 119.4°C. The glass transition temperature decreased from 58.9°C to 27.8°C, enhancing the damping performance at room temperature. It was discovered that introducing suspension chains with the SiOSi structure would delay the decomposition of soft segments and enhance heat resistance. Additionally, when the content of the suspension chain is raised to 66%, the hydrophobicity of polyurethane reaches the maximum level and the elongation at break attains 423% ± 12%.

Design and optimization of two-terminal InGaP/Si tandem solar cell through numerical simulation

Abstract The III-V/Si double junction solar cells demonstrate cost-effective performance comparable to III-V/III-V tandems, with an efficiency of 35.9%, below the 43% theoretical limit. Considering monolithic InGaP//Si based tandem solar cell, this work dealt with the optimization of its efficiency as a function of layer thicknesses and dopings. Considering ideal optoelectronic parameters of materials, numerical simulations were performed by using Silvaco/ATLAS TCAD software. They were conducted within the context of a multi-step optimization procedure that was proposed in this work. The obtained optimum tandem InGaP//Si structure reached an unprecedented power conversion efficiency of 40.74% under 1.5G spectrum.

Double Carbon-Species Coated Porous Silicon Anode Induced by Interfacial Energy Reduction for Lithium-Ion Batteries.

The rapid development of electric vehicles necessitates high-energy density Li-ion batteries for extended range. Silicon is a promising alternative to graphite anodes due to its high capacity; however, its substantial volume expansion during cycling leads to continuous growth of the solid electrolyte interphase and significant capacity fading. This study addresses these issues by designing a porous Si structure combined with a double carbon-species coating layer, induced by low interfacial energy in a scalable process. Carbon and graphene are located on Si surfaces, forming a close interface that maintains electrical contact, suppresses lithium consumption, and enhances charge transfer properties. The composite anode with a double carbon-species coating on Si demonstrates rapid stabilization with increasing coulombic efficiency, achieving a specific capacity of 1,814 mAh g-1 at 0.2 C and a high-rate capability of 1,356 mAh g-1 at 10C. Additionally, in a full-cell configuration with LiFePO4, it recorded a specific capacity of 161 mAh g-1 at 0.2 C. These results show the potential of porous Si with a carbon-graphene coating for stable, high-capacity operation in Li-ion batteries, offering new insights into high-performance electrochemical systems. Moreover, the double carbon-species coating derived from a scalable surface chemistry-based process presents a realistic alternative for industrial applications.

On the work-hardening behaviour of the additively manufactured Al-Si-Mg alloys: Composite-like versus networked microstructure

Al-Si-Mg alloys are widely used for manufacturing components via laser powder bed fusion in various industrial applications where ductility and the capacity to accommodate the strain hardening are key criteria. The ductility of the laser powder bed-fused Al alloys has become a crucial property due to their fine cellular microstructure. Post-processing heat treatments improve ductility, but resultant microstructural changes affect the work-hardening behaviour, deformability, and uniform elongation values. This study aims to investigate the work-hardening capability, uniform elongation and deformability of AlSi7Mg and AlSi10Mg samples after different post-processing heat treatments by using tensile tests, optical and scanning electron microscopies. At aging temperatures below 200 °C, the fully cellular structure of eutectic Si governs both the work-hardening behaviour and the strengthening mechanisms, despite the precipitation phenomenon. When direct-aging temperatures exceed 200 °C, the coarsening of the Si-eutectic network modifies work-hardening behavior (Stages 1–3), accentuating the effects induced by the precipitates. Artificial aging highlights the role of precipitates in controlling both work-hardening properties and deformability.

The Effect of Dihydromyricetin (DMY) on the Mechanism of Soy Protein Isolate/Inulin/Dihydromyricetin Interaction: Structural, Interfacial, and Functional Properties.

The combination of proteins with polysaccharides and polyphenols is expected to improve their physicochemical and functional properties. In this study, a novel plant-based antioxidant emulsifier was formed by soybean protein isolate (SPI), inulin (INU), and dihydromyricetin (DMY). Based on the binary system of SPI/INU, we focused on exploring the effect of the DMY concentration (0.5 mg/mL~2.5 mg/mL) on the formation and properties of the ternary complex. The structure, interaction mechanism, and interfacial and functional properties of the ternary complex were investigated. The results indicate that compared to the SPI/INU binary complex, the SPI/INU/DMY ternary complex had a significant decrease in particle size (~100 nm) and a slight decrease in absolute zeta potential. The SPI/INU binary complex with DMY mainly interacted by hydrogen bonding and hydrophobic interactions. Due to the incorporation of DMY, the structure of SI was denser and more flexible. The ternary complex exhibited an ideal three-phase contact angle and demonstrated better foaming and antioxidant ability. Additionally, compared to SPI/INU, the ternary complex had a significant improvement in EAI. These results provide a strategy for polyphenols to modify the structure, interfacial properties, and functions of protein/polysaccharide complexes. This provides a potential reference for the preparation of more ternary complexes with excellent emulsifying and antioxidant properties for application in emulsions.

Single-layer black phosphorus-enhanced narrowband perfect absorber in the terahertz range

In this paper, a narrowband absorber based on black phosphorus (BP) is proposed. By utilizing a single-layer BP, a Si structure with four etched holes, and a perfectly electrically conductive (PEC) plate, multi-band absorption can be achieved in the range of 3.8 THz to 5.0 THz. The location and absorbance of the three peaks are 4.32 THz (99.7 %), 4.53 THz (95.6 %), and 4.69 THz (56.7 %), respectively. The anisotropy of the BP structure leads to different absorption spectra when illuminated by TE and TM polarized light sources. Altering the electron doping in BP allows control over the position and intensity of absorption peaks. Upon examining the electric field distribution of the absorber, it is evident that the dominant physical mechanism is the localized surface plasmon resonance (LSPR). Overall, the monolayer BP absorber designed in this study can be utilized to construct a polarimetric sensor for infrared wavelengths. Additionally, it provides a valuable reference for 2D anisotropic plasma devices.

Fabrication of thick Cr masks for reactive ion substrate etching by electron beam lithography and lift-off techniques

Fabrication of tall Cr nanostructures of different shapes by lithography and lift-off processes is demonstrated. By varying resist thickness, metal layer thickness, and diameter of holes in the resist mask, it is demonstrated that metal structures with shapes ranging from sharp-tipped conical over flat-top cones to nearly cylindrical can be fabricated. A comparison of resist layer dissolution in acetone, covered by Ag and Cr films, reveals that Cr films grow with an open structure of particles that allow rapid solvent diffusion through Cr layers that are several hundred nanometers thick. On the other hand, the 2D growth of Ag on the resist forms a barrier against acetone diffusion. The open structure of Cr enables the lift-off process to fabricate several-μm-high nanostructures using a single resist layer. As an example, high-aspect-ratio Si structures are demonstrated by reactive ion etching using thick Cr layers as a mask, fabricating nanopillars with 3 μm height at room temperature.

Dramatic Enhancement Enabled by Introducing TiN into Bread-like Porous Si-Carbon Anodes for High-Performance and Safe Lithium Storage.

Doping modifications and surface coatings are effective methods to slow volume dilatation and boost the conductivity in silicon (Si) anodes for lithium-ion batteries (LIBs). Herein, using low-cost ferrosilicon from industrial production as the energy storage material, a bread-like nitrogen-doped carbon shell-coated porous Si embedded with the titanium nitride (TiN) nanoparticle composite (PSi/TiN@NC) was synthesized by simple ball milling, etching, and self-assembly growth processes. Remarkably, the porous Si structure formed by etching the FeSi2 phase in ferrosilicon alloys can provide buffer space for significant volume expansion during lithiation. Highly conductive and stable TiN particles can act as stress absorption sites for Si and improve the electronic conductivity of the material. Furthermore, the nitrogen-doped porous carbon shell further helps to sustain the structural stability of the electrode material and boost the migration rate of Li-ions. Benefiting from its unique synergistic effect of components, the PSi/TiN@NC anode exhibits a reversible discharge capacity up to 1324.2 mAh g-1 with a capacity retention rate of 91.5% after 100 cycles at 0.5 A g-1 (vs fourth discharge). Simultaneously, the electrode also delivers good rate performance and a stable discharge capacity of 923.6 mAh g-1 over 300 cycles. This research can offer a potential economic strategy for the development of high-performance and inexpensive Si-based anodes for LIBs.

Ammonia Gas Sensing Using Porous silicon

Abstract Psi prepared by Electrochemical etching technique at invariable etching current density of 10 mA/cm2 and at different times (7 and 17) min. The porous Si structure was studied using XRD, (FE-SEM) and EDS. The process of sensing NH3 gas is carried out at different operating temperatures (R.t,80,130 and 200)°C and the gas concentration is constant. It is measured by changing the resistance of the sensor as a function of exposure time to the gas. The result showed the XRD patterns of the PS at (7 and 17) min etching time. the peak samples at (111) around 2θ = 28.5°. It is observed that the peak intensity declines with rising the etching time, and some structural parameters for porous silicon are calculated. From FE-SEM, the images show the sample prepared in (7 and 17) min with the depth of (6.18 12.82) μm, with a size of about 50 nm. Porous silicon that was produced in a time of 17 min has a higher sensitivity to NH3 gas than that of the sample that was produced in a time of 7 min. It was found that when the operating temperature changes from (R.T -200C°), the sensitivity of the samples changes with the stability of the etching time. The PSi sample (17 min) has a high sensitivity for NH3 gas at room temp.

Using TiO2 to capture hot electrons for self-powered position-sensitive photodetection.

As environmental issues arise, the demand for self-powered position-sensitive detectors (PSDs) is increasing because of their advantages in miniaturization and low power consumption. Finding higher efficiency schemes for energy conversion is paramount for realizing high-performance self-powered PSDs. Here, a surface plasmon-based approach was used to improve the energy conversion efficiency, and a plasmon-enhanced lateral photovoltaic effect (LPE) was observed in PSD with TiO2/Au nanorods (NRs)/Si structure. The Au NRs convert absorbed light energy into electricity by generating hot electrons, which are efficiently captured by the TiO2 layer, and the PSD is capable of generating position sensitivity as high as 251.75 mV/mm when illuminated by a 780 nm laser without any external power supply, i.e. about five times higher than similar sensors in previous studies. In addition, the position sensitivity can be tailored by the thickness of TiO2 films. The enhancement mechanism is investigated by a localized surface plasmon (LSP)-driven carrier diffusion model. These findings reveal an important strategy for high sensitivity and low energy cost PSDs while opening up new avenues for energy harvesting self-powered position sensors.

A unified moment tensor potential for silicon, oxygen, and silica

Si and its oxides have been extensively explored in theoretical research due to their technological importance. Simultaneously describing interatomic interactions within both Si and SiO2 without the use of ab initio methods is considered challenging, given the charge transfers involved. Herein, this challenge is overcome by developing a unified machine learning interatomic potentials describing the Si/SiO2/O system, based on the moment tensor potential (MTP) framework. This MTP is trained using a comprehensive database generated using density functional theory simulations, encompassing diverse crystal structures, point defects, extended defects, and disordered structure. Extensive testing of the MTP is performed, indicating it can describe static and dynamic features of very diverse Si, O, and SiO2 atomic structures with a degree of fidelity approaching that of DFT.

Nano-twinned silicon in Al-Si alloys for high wear-resistance

Wear-failure is the most common damage for power transmission components in the field of engineering materials, constituting approximately one-fourth in service loss. The development of high wear-resistant Al alloys plays a crucial role in reducing energy demand and weight, and then attributes to the achievement of dual-carbon target. Here we report a novel strategy to develop outstanding wear-resistant (the coefficient of friction of 0.31) Al-10 wt%Si alloys at room temperature, based on the formation of multiple parallel {111} twins and hierarchical {111}-{111} double twins by a route of combining ultrahigh pressure solid solution and electropulsing assisted aging (HPEP), which overwhelms all values of Al alloys, even Ti alloys and high entropy alloys reported so far. The microstructure, formation process and wear-resistant mechanism of nano-twinned Si have been clarified by transmission electron microscopy observations, molecule dynamics simulations and the first principles calculations. It demonstrates that the interactive nano-twinned Si structures are mainly introduced through twin-twin collision or the phase/matrix interface prohibition of twin motion, which are effective to restrain atom separation in contrast to eutectic Si perfect crystal, resulting in homogeneous wear-loss and long operation life. Those new results provide insights towards designing wear-resistant materials with high mechanical properties.

Enhanced Activation in Phosphorous-Doped Silicon via Dual-Beam Laser Annealing.

In this study, we conduct a comparative analysis of single-beam laser annealing (SBLA) and dual-beam laser annealing (DBLA) techniques for semiconductor manufacturing. In the DBLA approach, two laser beams were precisely aligned to simultaneously heat a phosphorus-doped silicon (Si) wafer. The main objective was to investigate the impact of the two annealing techniques on the electrical properties, crystalline structure, and diffusion profile of the treated phosphorus-doped Si at equivalent laser powers. Both SBLA and DBLA improved the electrical properties of the phosphorus-doped Si, evidenced by increased carrier concentration and reduced carrier mobility. Additionally, the crystalline structure of the phosphorus-doped Si showed favorable modifications, with no defects and improved crystallinity. While both SBLA and DBLA produced similar phosphorus profiles with no significant redistribution of dopants compared to the as-implanted sample, DBLA achieved a higher activation ratio than SBLA. Although the results suggest improved dopant activation with minimal diffusion, further studies are needed to clearly confirm the effect of DBLA on dopant activation and diffusion.

Rotationally invariant local bond order parameters for accurate determination of hydrate structures

Averaged local bond order parameters based on spherical harmonics, also known as Lechner and Dellago order parameters, are routinely used to determine crystal structures in molecular simulations. Among different options, the combination of the q ¯ 4 and q ¯ 6 parameters is one of the best choices in the literature since distinguishes between solid- and liquid-like particles and between different crystallographic phases, including cubic and hexagonal phases. Recently, Algaba et al. [J. Colloid Interface Sci. 623, 354, (2022)] have used the Lechner and Dellago order parameters to distinguish hydrate- and liquid-like water molecules in the context of determining the carbon dioxide hydrate-water interfacial free energy. According to the results, the preferred combination previously mentioned is not the best option to differentiate between hydrate- and liquid-like water molecules. In this work, we revisit and extend the use of these parameters to deal with systems in which clathrate hydrates phases coexist with liquid phases of water. We consider carbon dioxide, methane, tetrahydrofuran, nitrogen, and hydrogen hydrates that exhibit sI and sII crystallographic structures. We find that the q ¯ 3 – q ¯ 12 combination is the best option possible between a large number of possible different pairs to distinguish between hydrate- and liquid-like water molecules in all cases.

Simulation of the THF hydrate-water interfacial free energy from computer simulation.

In this work, the tetrahydrofuran (THF) hydrate-water interfacial free energy is determined at 500 bar, at one point of the univariant two-phase coexistence line of the THF hydrate, by molecular dynamics simulation. The mold integration-host methodology, an extension of the original mold integration technique to deal with hydrate-fluid interfaces, is used to calculate the interfacial energy. Water is described using the well-known TIP4P/Ice model, and THF is described using a rigid version of the TraPPE model. We have recently used the combination of these two models to accurately describe the univariant two-phase dissociation line of the THF hydrate in a wide range of pressures from computer simulation [Algaba et al., J. Chem. Phys. 160, 164718 (2024)]. The THF hydrate-water interfacial free energy predicted in this work is compared with the only experimental data available in the literature. The value obtained, 27(2) mJ/m2, is in excellent agreement with the experimental data taken from the literature, 24(8) mJ/m2. To the best of our knowledge, this is the first time that the THF hydrate-water interfacial free energy is predicted from computer simulation. This work confirms that the mold integration technique can be used with confidence to predict the solid-fluid interfaces of complex structures, including hydrates that exhibit sI and sII crystallographic structures.

Surface structure of MOVPE-prepared As-modified Si(100) substrates

In the pursuit of high-efficiency tandem devices for solar energy conversion based on III-V-semiconductors, low-defect III-V nucleation on Si(100) substrates is essential. Here, hydrogen and arsenic are key ingredients in all growth processes with respect to industrially scalable metalorganic vapor phase epitaxy. Our study provides insight into Si(100) surface preparation for the initial stage of III-V nucleation. The samples investigated, prepared on substrates with different offcut angles, show single domain surfaces consisting of rows of preferentially buckled dimers. Low energy electron diffraction and reflection anisotropy spectroscopy confirm well-defined (1 × 2)/(2 × 1) majority domains. Fourier-transform infrared spectroscopy revealed hydrogen bonding to the surface dimers, while no impurities were found by XPS. Density functional theory calculations support the experimental results and reveal a novel surface motif of H-passivated Si-As mixed dimers.

Mechanical properties of Si(1−x)–C(x): strength and stiffness of materials using LAMMPS molecular dynamics simulation

This study investigated the mechanical properties (elastic modulus, tensile strength, yield strength, and toughness) of different percent C of silicon carbide (SiC) using molecular dynamics simulations via the large-scale atomic/molecular massively parallel simulator (LAMMPS) with the uniaxial tensile test at four strain rates: 0.1, 0.5, 1.0, and 5.0 m s−1, using the Tersoff potential. The simulation uses 20 × 20 × 20 atoms (108.6 Å × 108.6 Å × 108.6 Å) of the diamond cubic structure of Si, then carbon atoms were placed randomly at 5% intervals from 0–50 percent C. Results show improved mechanical properties when increasing percent C until peaking at 25%, before decreasing. This is caused by the shortest bond length at 25 percent C from the increase of Si=C using the radial distribution function analysis. Increasing the strain rate generally improves the mechanical properties of the material. The deformation mechanism shows that increasing (decreasing) strain rate generally results in multiple (lesser) failure points with a ductile (brittle) fracture mode.

Genetic-algorithm-combined density functional theory calculations for investigating atomic properties of Si−Ge alloys

Compound semiconductors are expected to expand the possibilities of semiconductor applications. In particular, Ⅳ−Ⅳ compound semiconductors, such as silicon−germanium (Si−Ge) alloys, have received much attention over the past several decades. Although many scholars have conducted experiments on Si−Ge alloys, few scholars have conducted theoretical simulations on them. Thus, fundamental understanding of nanoscale phenomena in the Si−Ge alloys is still insufficient. To address this problem, we identified energetically stable structures of the Si−Ge alloys using density-functional-theory (DFT) first-principles calculations and genetic algorithm (GA) and evaluated various properties of the Si−Ge alloys. We confirmed that the formation energies of the stable structures identified by GA-combined DFT calculations were lower than those of other Si−Ge alloys registered in an existing crystal structure database. The lattice constants and electronic band gaps of these stable structures were evaluated using DFT calculations, and trends in their properties similar to those reported in previous experimental studies were verified. From the evaluation of coordination number according to the Boltzmann distribution, we found that homoelement bonds (Si–Si and Ge−Ge) are easier to form than heteroelement bonds (Si−Ge) in the stable structures of Si−Ge alloys at any composition.