Layers Of Different Materials Research Articles

Investigating the Performance Optimization of Three‐Quantum‐Well High Electron Mobility Transistor Device: Analyzing Operational Characteristics and Gate Voltage Influence

Quantum well AlGaN/AlN/GaN high electron mobility transistor (HEMT) devices are a unique kind of semiconductor device that make use of a heterostructure made up of layers of different materials. In this study, the operational characteristics and performance optimization of HEMT devices, with a specific emphasis on the behavior of three‐quantum‐well (3QW) HEMT devices, are explored. The impact of gate voltage is explored and is observed that higher gate voltages result in lower pinch‐off voltages and higher saturation drain currents. In these findings, valuable insights for optimizing circuit designs and ensuring dependable operation across a range of electronic applications are offered. In addition, In this study, the device's ability to detect changes in gate voltage and its nonlinear characteristics is emphasized, providing valuable information for improving the device's performance. Additionally, the benefits of HEMT devices with negative threshold voltages are explored. Devices utilizing AlGaN/AlN/GaN structures demonstrate exceptional performance characteristics, such as rapid switching capabilities, high energy efficiency, and low noise performance, making them well suited for a wide range of scientific and technological applications. Finally, when comparing a QW HEMT device at different drain bias conditions (Vd = 1 V and Vd = 5 V), noticeable variations suggesting improved performance with higher drain bias.

Direct measurement of microwave loss in Nb films for superconducting qubits

Niobium films are a key component in modern two-dimensional superconducting qubits, yet their contribution to the total qubit decay rate is not fully understood. The presence of different layers of materials and interfaces makes it difficult to identify the dominant loss channels in present two-dimensional qubit designs. In this paper, we present the study that directly correlates measurements of RF losses in such films to material parameters by investigating a high-power impulse magnetron sputtered (HiPIMS) film atop a three-dimensional niobium superconducting radio frequency (SRF) resonator. By using a 3D SRF structure, we are able to isolate the niobium film loss from other contributions. Our findings indicate that microwave dissipation in the HiPIMS-prepared niobium films, within the quantum regime, resembles that of record-high intrinsic quality factor of bulk niobium SRF cavities, with lifetimes extending into seconds. Microstructure and impurity level of the niobium film do not significantly affect the losses. These results set the scale of microwave losses in niobium films and show that niobium losses do not dominate the observed coherence times in present two-dimensional superconducting qubit designs, instead highlighting the dominant role of the dielectric oxide in limiting the performance. We can also set a bound for when niobium film losses will become a limitation for qubit lifetimes.

Role of reactive transport in the alteration of vitrified waste packages: the MOS model

The MOS model (acronym coming from the French MOdèle Simplifié) was born from the desire to have a simple tool that can quantify the contribution of the diffusive reactive environment to the alteration of a vitrified nuclear waste package in deep geological disposal conditions. In the model, this environmental contribution consists partly of the ability of iron, metallic casing corrosion products, and argillite to consume silicon, and partly of the brake on diffusive transport provided by silicon through the successive layers of environmental material. It is a modeling tool serving as an intermediary between operational modeling for the calculation of the source term from the glass, mathematically more simple and giving higher upper margins, and models that use geochemistry and transport, giving greater accuracy for the interactions between glass and its environment. The goal of the MOS model is to calculate the possible impact of silicon reactive diffusion on the alteration rate within the different layers of material surrounding nuclear glass. This article lists the simplifying hypotheses on which the MOS is based, presents the digital resolution method for an environment consisting of several successive layers with different reactivity and transport properties, and explains the model’s implementation.

Impact of using dual back surface field layers of different materials on GaAs single junction solar cell performance

This research aspires to investigate the impact of employing dual BSF layers on the performance of single junction GaAs solar cells using the Silvaco TCAD simulator. A layer of GaAs, InGaP, and InAlGaP has been implemented as a second BSF layer on top of the original BSF layer of the n-InGaP/n-GaAs/p-GaAs/p-InAlGaP structured solar cell. The results show that using GaAs as a second BSF layer has increased the carrier’s recombination and degraded the cell efficiency due to its lower energy bandgap, which creates a potential well that lessens the number of photogenerated carriers flowing through the conduction band toward electrodes. However, adding InGaP and InAlGaP as a second BSF layer decreases the recombination rate and generates a broad electric field region leading to extra photogenerated carriers drifting through the cell, which increases the efficiency from 29.42% to 29.81% for the case of using InGaP and 30.33% for the case of using InAlGaP. Furthermore, increasing the thickness and doping of the second BSF layer reduces the carriers’ recombination at the boundaries of this layer, which implies efficiency enhancement.

Modeling swift heavy ion irradiation of substrate-supported two-dimensional material via two-temperature molecular dynamics simulations

This study employs two-temperature molecular dynamics simulations to investigate swift heavy ion irradiation of SiO2 substrate-supported two-dimensional material graphene. Material-dependent electronic and thermal properties are integrated into each region to model the energy transfer between the electronic and atomic subsystems of the studied materials. Simulations of interactions with Xe heavy ions are performed with ion kinetic energies ranging from 0.5 to 25 GeV with electronic stopping powers from ∼2.6 to 17.7 keV/nm. With the studied ion energy range, nanopores with a diameter of up to 5 nm can be formed in graphene due to the thermally driven sputtering effect, while amorphization occurs along the ion track in the SiO2 substrate. The coupling between the substrate and two-dimensional material significantly impacts the structural change due to heat transfer and atomic interactions among different layers of materials. The method applied in this work provides a valuable tool for modeling and understanding the structural modifications induced by ion irradiation in layered structures.

Optimized Fabrication Process and PD Characteristics of MVDC Multilayer Insulation Cable Systems for Next Generation Wide-Body All-Electric Aircraft

For wide-body all-electric aircraft (AEA), a high-power-delivery, low-system-mass electric power system (EPS) necessitates advanced cable technologies. Increasing voltage levels enhances power density yet poses challenges in aircraft cable design, including managing arc-related risks, partial discharges (PDs), and thermal management. Developing multilayer multifunctional electrical insulation (MMEI) systems for aircraft applications is a feasible option to tackle these challenges and reduce the size and mass of cable systems. This approach involves selecting layers of different materials to address specific challenges. Our prior research concentrated on the modeling and simulation-based design of MMEI systems for MVDC power cables. Experimental tests are essential for determining the behavior of PDs under varying pressure conditions. Also, the dielectric strength and time to failure of the designs need to be assessed. In this work, the fabrication process of a down-selected MMEI flat configuration is discussed and analyzed. This paper analyzes the fabrication process of power cables employing MMEI configurations and evaluates the PD characteristics of down-selected ARC-SC-T-MMEI cable samples. This study presents a detailed analysis of the characteristics of PD under atmospheric and low-pressure conditions, which will provide essential insights into the design of MVDC cables for future AEA applications.

Nonlinear interfacial contact laws in multi-layer elastic-viscoelastic structural systems

Layered structures are widely used in construction, such as pavement structures consisting of multiple layers of different materials or interfaces between bricks and mortar in masonry structures, etc. In analyzing such structures, understanding the properties of the interface between two layers of materials is essential. If one layer of material contains cracks and layers exhibit viscoelastic behavior, determining the properties of the interface becomes challenging. This study proposes a constitutive mechanical law to model the behavior of the interface between a microcracked viscoelastic medium and an undamaged elastic body based on the homogenization method. The interface is modeled by a layer of zero thickness. The coupling between the homogenization technique and the Griffith’s theory is used to provide the effective behavior of the micro-cracked medium. The interface is modelled as an effective medium (EF) characterized by normal and tangential stiffnesses (CN, CT ). In this work, two viscoelastic models are considered, i.e., Burger and Modified Maxwell. The formulas of CN and CT for two cases of crack distributions (isotropic and transversely isotropic) are obtained by asymptotic techniques where the thickness of the joint tends to zero

Enhancement of the mechanical properties in ultra-low weight SWCNT sandwiched PDMS composites using a novel stacked architecture

This study focuses on enhancing the mechanical properties of thin, soft, free-standing films via a layer-by-layer (LBL) fabrication process called LBL-FP. Soft polymer nanocomposite (PNC) thin films, combining polydimethylsiloxane (PDMS) and single-walled carbon nanotubes (SWCNT) at ultra-low loadings using a unique bottom-up LBL-FP, are examined. Two different structures of layered composites, (i) LBL PNCs- Layered composites with alternating layers of PDMS and SWCNT, (ii) Bulk PNCs- Layered composites with SWCNT dispersed in the bulk of PDMS, are comparatively investigated for their structural and mechanical properties. Silane-functionalized SWCNT strengthens the chemical bonding with PDMS, improving adhesion and dispersion. Mechanical analysis using nanoindentation, delamination, and dynamic analysis highlights the advantages of LBL PNCs with alternating layers of PDMS and SWCNT. Notably, LBL PNC (0.5 wt%) exhibits significant improvements, such as 2.6X increased nanoindentation resistance, 3X improved viscoelasticity, and (2–5)X enhanced tensile properties in comparison with neat PDMS. Due to this, LBL PNCs offer potential for soft, lightweight applications like wearables, electromagnetic interference shielding materials, and strain sensors while advancing composite thin film mechanics. The study emphasizes using a stacked architecture to produce PDMS-SWCNT multilayered PNCs with improved mechanics utilizing ultra-low concentrations of SWCNT. This first-of-its-kind stack design facilitates possibilities for lightweight composites utilizing less fillers. The LBL assembly involves the stacking of alternating layers of different materials, each contributing specific properties to enhance the overall strength and toughness of the structure.

Investigation of mechanical behavior of glass fiber reinforced extruded polystyrene core material composites.

Layered composites are composite materials created by combining different layers of materials. Each layer can possess unique properties, often tailored to meet specific application or design requirements. These composites have found applications in various sectors due to their features, which include lightness, excellent impact properties, and customization according to specific application areas. In this study, glass fiber reinforced polymer foam core layered composite materials were produced. EPS polymer foam was used as the core material. During production, polymer foams and fibers were bonded to the upper and lower sides of the foams using resin. Samples were produced with 4 and 6 layers on both sides, totaling 8 and 12 layers, respectively. The vacuum bagging method was employed in production, utilizing the manual laying technique. Upon completion of production, the materials were cut into sizes conforming to standards and converted into samples. Subsequently, three-point bending and low-speed impact tests were conducted on the produced samples. As a result of the impact tests, perforation occurred in the 8-layer samples of 200 g m-2 glass fiber composites, while rebound was observed in the 12-layer samples. Although more deformation occurred in the 8-layer glass fiber composites of 300 g m-2 than in the 12-layer samples, both sets of experiments resulted in rebound. Similar results to the impact tests were obtained in three-point bending tests, with higher strengths observed in the 12-layer samples compared to the 8-layer samples. Composite samples with fiber layers of 300 g m-2 exhibited better performance than samples with 200 g m-2 fibers.

Simulation of Multi-Layered Ballistic-Resistant Armour with Enhanced Energy Absorption Properties

This research focuses on the simulation of ballistic impact on multi-layered ballistic resistant armour. The efficiency of spring-loaded backing plate armour was compared with armour that has solid end plate with a view to introducing a more elastic surface that enhances energy absorption properties. The design consists of three major layers of different materials: fibre cement as the first layer; Kevlar as the second; and a spring-loaded backing plate made of steel as the third layer. SolidWorks was used to model the multi-layered armour and ANSYS Workbench Explicit Dynamics and AUTODYN 3D solver were used to simulate the ballistic impact. The simulation involved testing different configurations of the multi-layered structure. Analysis of the effect of the spring wire diameter on the armour's energy-absorbing characteristics was carried out while keeping the overall weight within the acceptable range. The simulation results for the different configurations were compared and the ballistic-resistant armour designed with a spring-loaded backing plate of 0.40 mm spring wire diameter gave the least deformation. The research suggested an enhanced armour performance using embedded elastic material.

The morphology and properties of recycled plastics made from multi-layered packages and the consequences for the circular economy

Multilayer packaging, comprising layers of different materials, offers various advantages for the storage of products but poses challenges concerning its recyclability. The layers provide specific functionalities (strength, barrier properties) but their combination results in incompatibilities and layer inseparability, limiting recyclability. Sustainable designs for multilayers hold great potential to meet the European Union's recycling targets, as they account for up to 20% of flexible films. However, this study demonstrates that the majority of investigated packaging structures does not comply with current guidelines for sustainable packaging design. Contamination by polymers, especially the combination of polyethylene terephthalate with polyolefins, leads to embrittlement of the recyclate, making reprocessing into products of similar economic value impossible. Holistic design choices and material selection based on legal guidelines, management of expectations and profit margins, and harmonization of processes and product appearances to bridge the gap between design for and from recycling of multilayer packaging are suggested.

Mono-component bacterial cellulose heterogeneous membrane mediated by ionic liquids for osmotic energy harvesting

The massive reserves of osmotic energy existing in estuary will be highly desired as promising energy source that avails to solve the problem of energy shortage and environment deterioration. The ion transport membrane is core component optimized through composite membrane heterostructure to maximize the osmotic energy harvesting but suffer from gaps and resistance increase, which limit their practical applications. Here we demonstrate mono-component heterogeneous regenerated bacterial cellulose (RBC) membranes fabricated by subtle regenerated technique through Ionic Liquids (ILs). Such membranes obtain heterogeneous nature by the difference in fiber intertwining states due to the different treatment conditions on both sides. It achieves osmotic energy conversion with maximum power density of 0.70 W·m−2at 100-fold, which provides ingenious strategy for excellent performance and low-cost osmotic energy harvesting. By minimizing pores and maximizing the surface charges, energy barriers can be lowered, ion permeable and selective transport channels for energy harvesting device can be increased, as supported by the numerical simulation. This is the first time the construction strategy for mono-component heterogeneous membrane mediated by ILs for osmotic energy harvesting is proposed, which averts gaps between the layers of different materials effectively and provides theoretical guidance for subsequent in-depth research on mono-component ion-selective heterogeneous membrane.

Formal derivation of a new sediment transport model using a multiscale procedure: Numerical Validation

We study in this work structures formed under a unidirectional flow. The main problem that addresses sediment transport by aquatic flow. We present the formal derivation of a new sediment transport model by using a multiscale procedure in time and space. We consider two non-miscible layers of different materials with physical properties by including friction. Interactions at the fluid-sediment interface and those internally sediment are also taken into account. The derived model is the Saint–Venant–Exner type obtained by coupling a Saint-Venant system governing the hydrodynamic component and an Exner equation describing the morphodynamical component. The first part of this work takes into account two major contributions namely the formal derivation of new unidirectional Saint–Venant–Exner model inspired by the work in Fernández-Nieto et al. (2017) and the introduction of a new multiscale parameterization in space-time characterized by the combination of classical variability and rapid variability of solutions. However, we have limited ourselves to the case of a first order approximation which does not include viscosity terms. Further analysis of the second order approach leading to a viscous model can be deduced from the work in Fernández-Nieto et al. (2013). We also propose a numerical study of the derived model. Thus, we develop finite volume numerical schemes. The numerical approach employs a Riemann solver, and various options ranging from an exact solver to an approximate Riemann HLL-type and HLLC-type solvers. We did some numerical tests leading to consistent and effective results.

Assessment of Biological Trickling System with Different Layers of Material for Grey Water Treatment

Greywater reuse is an attractive alternative whenever water resources are scarce because it can lower water demand and increase available water supply. This study used simple, easy-to-find treatment and purification methods to examine how gray sewage from homes could be used in agriculture. The primary motivation for reducing agricultural fertilizer consumption is financial gain. If feasible, society can achieve more acceptable economic objectives. The multimedia biofilter, a biological trickling filter, treats wastewater biologically by attaching biomass to various media. In this investigation, raw greywater was settled for two hours. The same influent was used to compare and contrast two treatment approaches. The treatment methods include an exploration of the effectiveness of two filters. The first filter comprises sand, gravel, cotton, and activated carbon filtration layers. The second contains sand, gravel, brick bat, wood chips, and rice husk filtration layers. Gray water was purified utilizing a sand filtration system (gravel and sand), along with the addition of other materials to improve the effectiveness of the treatment. These additional materials included cotton, active carbon, brick, wood chips, and rice husks. Chemical tests were performed on the graywater, and each component was identified. Overall, the sand-gravel-cotton-activated carbon filter improved greywater quality to irrigation standards by reducing organic matter. The second filter (made of sand, gravel, brick, wood chips, and rice husks) is a low-cost greywater recycling unit. But there is still room for improvement in how well these filters work with higher and changing loads and how long their materials last. As a result, most of the filter materials used were waste products generated inside homes and are said to be the least expensive and most inexpensive filters.

Experimental study of the double-layer cylindrical shell under uniform axial pressure

In this paper, the buckling performance of the double-layer cylindrical structure with different layers of materials under uniform axial pressure is studied. Three identical double-layer and single-layer cylindrical thin shells are fabricated, measured, and tested respectively. The results indicate that the average ultimate strength of the double-layer cylinder is about 1.91 times that of the single-layer cylinder.

Effect of loading paths on hydroforming ability of stepped hollow shaft components from double layer pipes

The step hollow shaft components are composed of two layers of different materials, they are formed using tube hydroforming process due to its high strength and rigidity, low weight and flexible profiles, compared to traditional casting, welding, and forming methods. These products are effectively used in industries such as the automotive, shipbuilding, aerospace and defense, and oil and gas sectors. The success of various double layer pipe hydroforming process depends on several factors, with the most important being the internal pressure path and axial loading path. This paper presents research on the effect of input loading paths on the hydroforming ability of a different two-layer metal structure - an outer layer of SUS304 stainless steel and an inner layer of CDA110 copper - using 3D numerical simulations on Abaqus/CAE software. Output criteria were used to evaluate the forming ability of the formed components, including Von Mises stress, Plastic strain component (PEmax), wall thinning, and pipe profile, based on which the input loading paths were combined during the forming process. These output criteria allow for more accurate predictions of material behavior during the hydroforming process, as well as deformation and stress distribution. This can support the design process, improve product quality, reduce errors, and increase production efficiency. The research results can be applied as a basis for optimizing load paths for the next experimental step in the near future, for undergraduate and graduate training, as well as allowing designers and engineers to optimize the process of hydroforming of different 2-layer tubes, reducing costs, improving accuracy, flexible design, minimizing risks, and increasing efficiency

Bio‐Inspired Homologous Magnesium‐Based Reflective Filters with Angular Heterochromatic Structural Colors

AbstractThe existing color filter implementation schemes are prone to introduce prestress during the preparation process due to the large difference in thermal expansion coefficients of different layers of materials, resulting in poor mechanical stability. Inspired by beetle forewings’ structure, it is proposed to construct asymmetric Fabry–Perot (F‐P) angular heterochromatic structural colors utilizing homologous materials through a continuous deposition method of magnetron sputtering technology. The fabricated large‐area F‐P‐type reflective filters not only exhibit high color saturation but also achieve good bonding ability between the layers with a steady‐state friction coefficient of ≈0.1. The large‐area reflective filter can achieve different colors such as blue, yellow, violet, and green, which is in agreement with the simulation results. This work not only provides a new design method for advanced decorative applications but also provides protection to the substrate.

Hardmask engineering by mask encapsulation for enabling next generation reactive ion etch scaling

Miniaturization and scaling of semiconductor devices require development of innovative techniques to sustain advancements. A promising trend is the migration from 2D to 3D device architectures that necessitate fabrication of high-aspect-ratio narrow features through layers of different materials. Reactive ion etching can achieve this but poses unique challenges due to the requirement of etch chemistries capable of etching dissimilar materials with varying etch rates while maintaining high productivity. The choice of hardmask is also crucial, as it plays a critical role in determining efficacy of the etch process and the final shape of the feature being etched. To address these challenges, we introduce a new concept of hardmask engineering that involves a bilayer hardmask scheme consisting of a patterned conventional hardmask encapsulated with a thin layer of etch-resistant ruthenium (Ru) layer. Experimental results for etching multilayer stacks consisting of alternating pairs of SiO2 and Mo show that this engineered hardmask results in improved hardmask remaining and etch profile with smaller critical dimensions (CDs). Technology computer-aided design simulations with the Ru encapsulation layer on conventional carbon hardmask demonstrate increased poly-Si etch depth with reduced bow CD. This concept can be extended to any semiconductor nanofabrication step involving high-aspect-ratio etching where precise control of CDs is essential in the vertical direction.

Experimental Study on Flexural Behavior of RC–UHPC Slabs with EPS Lightweight Concrete Core

This paper presents an experimental investigation that focuses on the flexural behavior of an innovative reinforced concrete–ultra-high performance concrete slab with an expanded polystyrene lightweight concrete core. This type of slab is proposed to serve the semi-precast solution, in which the bottom layer is ultra-high performance concrete working as a formwork during the construction of semi-precast slab, the expanded polystyrene lightweight concrete layer is used for the reduction of structure self-weight, and the top layer is normal concrete designed to withstand compressive stress when the slab is loaded. Two similar large-scale specimens with dimensions of 6200 mm × 1000 mm × 210 mm were fabricated and tested under four-point bending conditions to investigate the flexural behavior of composite slab. Test results indicated that three different layers of materials can work effectively together without separation. The bottom ultra-high performance concrete layer leads to the high ductility of the slab and has a good effect in limiting the widening of the crack width by forming other cracks. According to design code ACI 544.4R, a modified distribution stress diagram on the composite section was proposed and proven to be suitable for the prediction of flexural strength of the composite section with an error of 3.4% compared to the experimental result. The effect of the ultra-high performance concrete layer on the flexural strength of the composite slab was clearly demonstrated, and for the case in this study, the ultra-high performance concrete layer improves the flexural strength of the slab by about 11.5%.

Realizing the heteromorphic superlattice: Repeated heterolayers of amorphous insulator and polycrystalline semiconductor with minimal interface defects.

An unconventional "heteromorphic" superlattice (HSL) is realized, comprised of repeated layers of different materials with differing morphologies: semiconducting pc-In2 O3 layers interleaved with insulating a-MoO3 layers. Originally proposed by Tsu in 1989, yet never fully realized, the high quality of the HSL heterostructure demonstrated here validates the intuition of Tsu, whereby the flexibility of the bond angle in the amorphous phase and the passivation effect of the oxide at interfacial bonds serve to create smooth, high-mobility interfaces. The alternating amorphous layers prevent strain accumulation in the polycrystalline layers while suppressing defect propagation across the HSL. For the HSL with 7:7nm layer thickness, the observed electron mobility of 71 cm2 /Vs, matches that of the highest quality In2 O3 thin films. The atomic structure and electronic properties of crystalline In2 O3 / amorphous MoO3 interfaces are verified using ab-initio molecular dynamics simulations and hybrid functional calculations. This work generalizes the superlattice concept to an entirely new paradigm of morphological combinations. This article is protected by copyright. All rights reserved.