Buffer Layer Research Articles

In-situ constructed interface buffer layer enabled highly reversible Zn Deposition/Stripping for long-lifespan aqueous zinc metal anodes

Despite the advantages of high capacity, high safety and low cost, zinc anodes also face the inherent problems of dendritic growth, corrosion and passivation, vastly limiting the development and application of aqueous zinc ion batteries (AZIBs). Here, the epigallocatechin gallate (EGCG) was used as a hydroxyl-rich natural electrolyte additive for AZIBs. During charge–discharge process, the EGCG can be preferentially adsorbed on the zinc anode, and act as an interface buffer layer to weaken the direct contact between active water molecule and zinc anode. Based on this effect, the interface buffer layer is helped to inhibit the water-induced side reactions of hydrogen evolution, zinc corrosion and passivation, and lower the polarization overpotential, contributing to highly reversible Zn deposition/stripping behavior. As a result, the Zn||Zn symmetric batteries can maintain a stable cycling for more than 1500 h at 1.0 mA cm−2 and 1.0 mAh cm−2. Furthermore, the assembled Zn||MnO2 full batteries still delivered high capacity retention of 98.02 % after 400 cycles at 1.0 A/g. This finding enriches the design thoughts for the development of high-efficiency and practical AZIBs.

Investigation on thermal annealing effect on the physical properties of CuO-SnO2:F sprayed thin films for NO2 gas sensor and solar cell simulation

Thin films, owing to their versatility, are extensively employed in various applications, including solar cells and gas detection. In this study, CuO-SnO2:F thin films were fabricated using spray method. The influence of annealing temperature on their properties was examined. X-ray diffraction analysis of post-annealing at 300 °C revealed the emergence of the Cu2O phase, which disappeared at higher annealing temperatures of 500 °C. Substantial improvements in structural, optical, and electrical characteristics were observed, with the optimized films exhibiting heightened responsiveness at low NO2 gas concentration (4 ppm). The optimum operating temperature was determined at 150 °C, demonstrating small response and recovery times, and good reproducibility. Furthermore, Silvaco TCAD simulation was employed to model CIGS (Copper Indium Gallium Selenide) solar cells incorporating CuO-SnO2:F thin films as a buffer layer, yielding an impressive efficiency of 15.31 %.

Effective Promotion of Micro Damping of GO Hybrid PU–PF Copolymer Grinding Wheels on Precision Machining

The influence of damping and friction performance of grinding wheels on precision grinding was explored for the first time. GO hybrid PU-modified PF copolymers were prepared by in situ synthesis and adopted as a matrix for fabricating grinding wheels. FT-IR, DSC, TG, and mechanical property tests showed the optimal modification when PU content was 10 wt% and GO addition was 0.1 wt%. Damping properties were investigated by DMA, and tribological characteristics were measured by sliding friction and wear experiments. The worn surfaces and fracture morphologies of GO hybrid PU–PF copolymers were observed by SEM. Distribution of components on the worn surfaces was explored by Raman mapping and EDS. The research results revealed that the PU component tended to be dispersed around the edges of corundum abrasives acting as a buffer layer of abrasive particles, which could provide micro-damping characteristics for abrasives, making the grinding force more stable during precision machining and facilitating a smoother surface quality of the workpiece.

Heterojunction interface engineering of C60 electron transport layer insertion enables efficient Cd-free Sb2Se3 solar cells

Antimony selenide (Sb2Se3) emerges as a promising semiconductor for solar energy conversion, attributed to its high light absorption and excellent photoelectric properties, coupled with notable stability and consistent stoichiometry. Yet, its application in thin-film solar cells is limited by non-radiative recombination losses at suboptimal heterojunction interfaces. Addressing this, we propose a strategy employing a C60 electron transport layer (ETL), thermally evaporated between the Sb2Se3 absorber and SnOx buffer layer. This approach not only increases the carrier density in SnOx but also passivates harmful defects like VO and OH−, thus reducing interfacial recombination. Incorporating C60 ETL improves the fill factor (FF) and open-circuit voltage (VOC) of the Sb2Se3 device, achieving a maximum power conversion efficiency (PCE) of 6.65 %. This finding highlights the significance of ETL-dependent interfacial engineering in enhancing Sb2Se3 solar cell performance, offering a novel and accessible solution to the primary challenge in developing Cd-free Sb2Se3 solar cells.

Prospects of buffer layer optimization for electrodeposited CZTS-based thin-film solar cell using SCAPS-1D

Kesterite Cu2ZnSnS4 (CZTS) has recently attracted the intensive attention of researchers as a significant photovoltaic material for the scalable production of thin film solar cells. We have particularly focused on replacing the conventional CdS buffer layer with non-toxic and earth-abundant materials of zinc stannate (Zn2SnO[Formula: see text] in environmentally friendly thin-film solar cells based on CZTS. Zinc stannate (ZTO) with a wide bandgap energy of about 3.33[Formula: see text]eV can be a promising material to reduce photon absorption loss and improve the photovoltaic performance of the device. Thus, the absorber and buffer layers were practically prepared to determine the bandgaps of layers for citation in SCAPS-1D simulation program. We employed chemical methods to deposit the CdS and CZTS layers and succeeded to obtain a high-quality kesterite phase of CZTS. The common configuration of FTO/CZTS/buffer/ZnO/AZO was the basis of the simulations in which, the thicknesses of the absorber and buffer layers were optimized by using the SCAPS-1D. According to the outcome of the simulations, the ZTO buffer layer has a better performance than CdS.

Tuning the Electronic Characteristics of Monolayer MoS2‐Based Transistors by Ion Irradiation: The Role of the Substrate

AbstractThis study explores defect engineering in 2D materials using ion beam irradiation to modify the electrical and optical properties with potential in advancing quantum electronics and photonics. Helium and neon ions ranging from 5 to 7.5 keV are employed to manipulate charge transport in monolayer molybdenum disulfide (MoS2). In situ electrical characterization occurs without vacuum breakage post‐irradiation. Raman and photoluminescence spectroscopy quantify ion irradiation's impact on MoS2. Small doses of helium ion irradiation enhance monolayer MoS2 conductivity in field‐effect transistor geometry by inducing doping and substrate charging. Findings reveal a strong correlation between the electrical properties of MoS2 and the primary ion used, as well as the substrate on which the irradiation occurred. Using hexagonal boron nitride (h‐BN) as a buffer layer between MoS2 flake and SiO2 substrate yields distinct alterations in electrical behavior subsequent to ion irradiation compared to the MoS2 layer directly interfacing with SiO2. Molecular dynamics simulations and density functional theory provide insight into experimental results, emphasizing substrate influence on measured electrical properties post‐ion irradiation.

Solution‐Processed Sb2(S,Se)3 Seed‐Assisted Sb2Se3 Thin Film Growth for High Efficiency Solar Cell

Antimony selenide (Sb2Se3) emerges as a promising sunlight absorber in thin film photovoltaic applications due to its excellent light absorption properties and carrier transport behavior, attributed to the quasi‐one‐dimensional Sb4Se6‐nanoribbon crystal structure. Overcoming the challenge of aligning Sb2Se3‐nanoribbons normal to substrates for efficient photogenerated carrier extraction, a solution‐processed nanocrystalline Sb2(S,Se)3‐seeds are employed on the CdS buffer layer. These seeds facilitate superstrated Sb2Se3 thin film solar cell growth through a close‐space sublimation approach. The Sb2(S,Se)3‐seeds guided the Sb2Se3 absorber growth along a [002]‐preferred crystal orientation, ensuring a smoother interface with the CdS window layer. Remarkably, Sb2(S,Se)3‐seeds improve carrier transport, reduce series resistance, and increase charge recombination resistance, resulting in an enhanced power conversion efficiency of 7.52%. This cost‐effective solution‐processed seeds planting approach holds promise for advancing chalcogenide‐based thin film solar cells in large‐scale manufacturing.

Impact of B4C buffer layer on interface diffusion in Cr/Sc multilayers: combined study by x-ray reflectivity, scattering and fluorescence

In thin film multilayer based optical componentsof x-ray imaging system, diffusion of one material into the other degrades the reflectivity of the mirrors severely. Along with this thermodynamically driven diffusion, there are also growth generated interface roughness of different special frequencies and microstructures which can increase the diffused scattering from the multilayer and reduce the resolution of an image. Generally grazing incidence x-ray reflectivity in specular geometry (specular GIXR) and diffused x-ray scattering measurement in rocking scan geometry yield information regarding microstructure and overall diffusion at the interfaces of a multilayer. In this paper it is shown that grazing incidence x-ray fluorescence (GIXRF) measurement in standing wave condition alongwith the above measurements can give precise information regarding element-specific diffusion at the interfaces of a multilayer structure. Periodic multilayers made of 75 Cr/Sc bilayers with bilayer thickness ∼4 nm with and without B4C barrier layer of 0.2 nm thickness at the interfaces have been prepared using ion beam sputtering system and characterized by GIXR, diffused x-ray scattering and GIXRF measurements using synchrotron x-ray radiation just above the Cr K-edge. From the above measurements, drastic reduction in interface diffusion of Cr and improvement of interface morphology after addition of B4C barrier layer at the interfaces of Cr/Sc multilayers have been observed which is also corroborated by cross-sectional transmission electron microscopy of the multilayers. Finally, in the water window soft x-ray region of 2.3–4.4 nm performance of these multilayers have been tested and the Cr/B4C/Sc multilayer with improved interface quality has been found to yield ∼30.8% reflectivity at 3.11 nm wavelength which is comparable with the best reported reflectivities in the literature at this wavelength.

Heteroepitaxial growth of Ga2O3 thin films on nickel-nanodot-induced buffer layers for solar-blind ultraviolet photodetector applications

Heteroepitaxial growth of gallium oxide (Ga2O3) thin films has been conducted on nickel (Ni)-nanodot-induced buffer layers using a mist chemical vapor deposition. The separation degree and droplet size of the Ni nanodots on sapphire substrates were controlled through a thermal annealing process, thereby being used as templates for the Ga2O3 thin-film growth. The growth of the inverted cone-shaped ε-Ga2O3 polymorph was observed on the nanodots while the α-Ga2O3 polymorph was grown on the sapphire substrate without nanodots, ultimately a thin film with a mixture of ε and α polymorphs can be achieved. By comparing photoresponses of metal–semiconductor–metal photodetectors fabricated on the thin film with the mixed polymorphs and on a single-crystalline α-Ga2O3 film, a promising template for using solar-blind photo-detecting applications has been verified.

High-Voltage Cable Buffer Layer Ablation Fault Identification Based on Artificial Intelligence and Frequency Domain Impedance Spectroscopy.

In recent years, the occurrence of high-voltage cable buffer layer ablation faults has become frequent, posing a serious threat to the safe and stable operation of cables. Failure to promptly detect and address such faults may lead to cable breakdowns, impacting the normal operation of the power system. To overcome the limitations of existing methods for identifying buffer layer ablation faults in high-voltage cables, a method for identifying buffer layer ablation faults based on frequency domain impedance spectroscopy and artificial intelligence is proposed. Firstly, based on the cable distributed parameter model and frequency domain impedance spectroscopy, a mathematical model of the input impedance of a cable containing buffer layer ablation faults is derived. Through a simulation, the input impedance spectroscopy at the first end of the cables under normal conditions, buffer layer ablation, local aging, and inductive faults is performed, enabling the identification of inductive and capacitive faults through a comparative analysis. Secondly, the frequency domain amplitude spectroscopy of the buffer layer ablation and local aging faults are used as datasets and are input into a neural network model for training and validation to identify buffer layer ablation and local aging faults. Finally, using multiple evaluation metrics to assess the neural network model validates the superiority of the MLP neural network in cable fault identification models and experimentally confirms the effectiveness of the proposed method.

Wet synthesis of Cu2MnSnS4 thin films for photovoltaics: Oxidation control and CdS impact on device performances

The manganese-based quaternary chalcogenide Cu2MnSnS4 could have the chance to promote the production of sustainable solar cells, but the reported photovoltaic efficiencies are still too poor to push the research on the topic. Herein, a low-cost, straightforward, and sustainable wet methodology to synthesise Cu2MnSnS4 thin films is reported. The main issues that hindered their power conversion efficiencies have been investigated. Firstly, the manganese oxidation state has been stabilised by fine-tuning the synthesis parameters. Cu2MnSnS4 was obtained in the crystalline structure of stannite, and no oxygen was found in the material bulk. Prototype devices in substrate configuration were produced, and the new record efficiency (η = 0.92 %) for wet-synthesised Cu2MnSnS4 was reached. Since the photovoltaic performances were poor despite the high quality of Cu2MnSnS4 produced, the interface between the light absorber material and the buffer layer, CdS, was investigated, and its suitability to work as an efficient photovoltaic p-n junction was evaluated. We reveal that the buffer layer deposition procedure highly impacts the composition of the Cu2MnSnS4 surface, and that band alignment between Cu2MnSnS4 and CdS is unfavourable. The statements have been sustained by X-ray diffraction and Raman analysis, X-ray and ultraviolet photoelectron, electron paramagnetic resonance, and energy dispersive X-ray spectroscopies.

Ultrafast UV Luminescence of ZnO Films: Sub‐30 ps Decay Time with Suppressed Visible Component

AbstractUltrafast sub‐100 picosecond luminescence is vital in many applications involving ultrafast events and time‐of‐flight systems. Materials exhibiting fast luminescence, such as barium fluoride (BaF2) and zinc oxide (ZnO), also suffer from an intrinsically slow nanosecond (ns) to microsecond (µs) luminescence. Here, 2.2 micrometer (µm)‐ to 5.7 µm‐thick undoped ZnO films on soda‐lime glass (SLG) substrates without a buffer layer by a hybrid pulsed reactive magnetron sputtering operating in the medium‐frequency range (MF magnetron) assisted by an electron cyclotron wave resonance (ECWR) plasma is deposited. The undoped ZnO films exhibited superior optical properties characterized by intense ultraviolet (UV) luminescence, unprecedented ultrafast decay times, and for the case of MF+ECWR‐deposited films, suppressed defect‐related visible luminescence. The 2.2 µm‐thick MF‐deposited film exhibited the fastest 9‐ps decay time at room temperature. The impressive properties of the films are attributed to the use of advanced deposition technology with properly tuned plasma parameters, especially a high degree of dissociation of molecular oxygen together with an increased proportion of activated zinc particles, leading to a higher deposition rate, better crystallinity, fewer defects, and a lower proportion of oxygen vacancies. These films will pave the way toward the development of time‐of‐flight detectors, high‐resolution nuclear imaging cameras, and high‐rate ultrafast timing devices.

Research on Single-Event Burnout Reinforcement Structure of SiC MOSFET.

In this paper, the single-event burnout (SEB) and reinforcement structure of 1200 V SiC MOSFET (SG-SBD-MOSFET) with split gate and Schottky barrier diode (SBD) embedded were studied. The device structure was established using Sentaurus TCAD, and the transient current changes of single-event effect (SEE), SEB threshold voltage, as well as the regularity of electric field peak distribution transfer were studied when heavy ions were incident from different regions of the device. Based on SEE analysis of the new structural device, two reinforcement structure designs for SEB resistance were studied, namely the expansion of the P+ body contact area and the design of a multi-layer N-type interval buffer layer. Firstly, two reinforcement schemes for SEB were analyzed separately, and then comprehensive design and analysis were carried out. The results showed that the SEB threshold voltage of heavy ions incident from the N+ source region was increased by 16% when using the P+ body contact area extension alone; when the device is reinforced with a multi-layer N-type interval buffer layer alone, the SEB threshold voltage increases by 29%; the comprehensive use of the P+ body contact area expansion and a multi-layer N-type interval buffer layer reinforcement increased the SEB threshold voltage by 33%. Overall, the breakdown voltage of the reinforced device decreased from 1632.935 V to 1403.135 V, which can be seen as reducing the remaining redundant voltage to 17%. The device's performance was not significantly affected.

Effect of alloy 625 buffer layer on corrosion resistance of nickel base hardfacing

Nickel base hardfacing alloys serve to mitigate corrosion losses at elevated temperatures. Efficacy of Nickel base hardfacing alloys can be compromised when applied onto Fe base substrates due to iron dilution in hardfacing. The degree of Fe dilution can be reduced by using advanced deposition methods and optimized deposition parameters. Gas Tungsten Arc Welding (GTAW) method is commonly employed for its cost-effectiveness and versatility, but it tends to induce higher Fe dilution due to increased heat input. This study aims to reduce the degree of Fe dilution and enhance corrosion resistance by introducing a nickel base buffer layer (alloy 625) between the nickel base hardfacing alloy and AISI 316L stainless steel substrate. For comparative purposes, Ni base hardfacing alloy was deposited on the substrate without any buffer layer. Hardfacing depositions were prepared using manual GTAW process. Process parameters namely, deposition current, voltage, travelling speed, pre-heating temperature, and cooling method were kept constant. Samples underwent aging at 1123 K for 4 h, followed by microstructural examination via optical and scanning electron microscopes. Iron (Fe) dilution quantification was performed using energy dispersive spectroscopy (EDS). The EDS analysis showed that the use of buffer layer between the hardfaced deposit and the substrate decreased the degree of Fe dilution in the hardfaced deposit. X-Ray diffraction (XRD) analysis was performed to identify various phases formed in the hardfaced deposit. Potentiodynamic polarization test was performed to assess the corrosion resistance of hardfaced deposit in 3.5 wt% NaCl solution. Results show significant improvement in corrosion resistance of hardfacings deposited sample with buffer layer as compared to those without buffer layer. Aging treatment further enhanced corrosion resistance. The corrosion resistance data is correlated with the microstructure and phases formed in various samples.

Growth mechanism and the properties of CIGS thin films for zero bias photodetector devices

CuInGaSe2 quaternary thin films have been deposited using a single-source, single-step thermal evaporation technique using hydrothermally fabricated CIGS powder. Highly crystalline, homogeneous, and stoichiometric CIGS powder source was prepared by a hydrothermal method and then evaporated at substrate temperatures of room temperature, 150°C, and 300°C. The bulk and surface structural, morphological, and optical properties of the samples were analyzed. The sample deposited at room temperature did not show any phase formation; however, increasing the substrate temperature resulted in the formation of binary and quaternary phases due to interdiffusion of the species. XPS and Raman spectra analysis revealed nanocrystalline Cu2Se phase formation at the interface, while the bulk of the sample remained single-phase CIGS. A higher deposition temperature also facilitated larger grain size and a more compact surface morphology. Increasing the substrate temperature increased the likelihood of interdiffusion of the species from the evaporation flux and controlled the bulk and surface properties of the samples. CIGS/CdS active photodetectors were fabricated by deposition of a CdS buffer layer, with the sample deposited at 150°C showing the highest photocurrent along with low response and recovery times at 0 V bias.

Hydrothermal synthesis of kesterite CZTSSe nanoparticles for highly efficient thin film

CZTSSe kesterite nanoparticles have been investigated for the efficient. The hydrothermal method has been used to prepare the material. The various characterization like X-ray diffraction (XRD), Raman scattering, Scanning Electron Microscopy (SEM) for (UV–Vis) ultraviolet–visible spectrophotometry and (EDS) energy-dispersive X-ray spectroscopy and of the prepared nano particles have been studied. Furthermore, numerical analysis of the synthesized material has also been investigated to optimize the performance for more characterization at the device level. For the optimization purpose, we have modelled a device structure of the hybrid buffer layer and optimized its physical parameters for the efficient. Theoretical efficiency is found to be 18.46 % for the prepared model. The results of this study show that Cu2ZnSn (S, Se)4 could be used as an absorbent layer for efficient solar cell.

Epitaxial growth and characterization of GaAs (111) on 4H-SiC

Epitaxial growth and characterization of GaAs (111) on 4H-SiC

Study on Anomalous Hall Effect and Spin-Orbit Torque Effect of TbCo-Based Multilayer Films.

The anomalous Hall effect and spin-orbit torque of TbCo-based multilayer films have been methodically studied in recent years. Many properties of the films can be obtained by the anomalous Hall resistance loops of the samples. We report on the effects of a structure composed of two heavy metals as the buffer layers on the anomalous Hall resistance loops of TbCo-based multilayers at different temperatures. The results showed that the coercivity increases dramatically with decreasing temperature, and the samples without perpendicular magnetic anisotropy at room temperature showed perpendicular magnetic anisotropy at low temperatures. We quantified the spin-orbit torque efficiency and Dzyaloshinskii-Moriya interaction effective field size of the films W/Pt/TbCo/Pt at room temperature by measuring the loop shift of anomalous Hall resistance. The results showed that the study of anomalous Hall resistance loops plays an important role in the study of spintronics, which can not only show the basic properties of the sample, but can also obtain other information about the sample through the shift of the loops.

Improving the emission properties of graphene–carbon nanotube hybrid nanostructures through functionalization with BaO nanoparticles and laser treatment

This paper presents the manufacturing technology of hybrid nanostructures based on a buffer layer of reduced graphene oxide (rGO) flakes with vertical single-walled carbon nanotubes (SWCNTs) and their bundles functionalized with BaO nanoparticles. Using density functional theory (DFT) calculations, supercells of rGO/SWCNT/BaO films were constructed and the patterns of the electron work function were revealed. It has been demonstrated that the electron work function is influenced by both the mass fraction of BaO nanoparticles and the inter-tube distance. Branched carbon nanostructure was formed using a pulsed laser irradiation. Fragmentation of BaO nanoparticles on the carbon surface was achieved. It was shown that after laser treatment, Ba(NO3)2 particles up to 200 nm in size were fragmented into smaller BaO nanoparticles with sizes of a few nanometers, covering the nanotubes. The field emission current–voltage characteristics (CVCs) were measured and showed a 42-fold increase in emission current compared to the nanostructure without BaO functionalization and laser treatment. BaO-functionalized hybrid carbon nanostructures are predicted to be efficient field cathodes, with a current density of at least 2 A/cm2, for use in X-ray tubes, field emission displays, and vacuum microwave devices.

Investigating the potential of WO3 and WS2 as Cd-free buffer layers in Sb2Se3-Based thin-film solar cells: A numerical study with SCAPS-1D software

In this numerical study, the performance of thin-film solar cells (TFSCs) based on Sb2Se3 with WO3 and WS2 materials as Cd-free buffer layers was investigated using SCAPS-1D software. WO3 and WS2 were chosen for their suitable band gaps, good electrical conductivity, and optical transparency. The proposed solar cell structures, Au/Sb2Se3/WO3/ITO and Au/Sb2Se3/WS2/ITO were theoretically examined, considering various factors such as conduction band offset, absorber and buffer layer thickness, doping concentrations, series and shunt resistances, temperature, activation energy, and C–V characteristic. The conduction band offset at the absorber/buffer interface showed spike-like configurations, with values of 0.38 eV and 0.23 eV for the WO3 and WS2 buffer layers, respectively. The optimized thickness for the absorber layer in both structures was 1 μm, while for WO3 and WS2 buffer layers, it was 0.1 μm and 0.05 μm, respectively. The optimized acceptor and donor doping concentrations were 1 × 1016 cm−3 and 1 × 1018 cm−3, respectively. The efficiency of the proposed photovoltaic devices was found to be 9.538 % (with Voc = 0.561 V, Jsc = 30.856 mA/cm2, FF = 55.84 %) and 10.151 % (with Voc = 0.558 V, Jsc = 29.189 mA/cm2, FF = 62.34 %) for structures with WO3 and WS2 buffer layers, respectively. These results suggest that using non-toxic materials like WO3 and WS2 as buffer layers can be an efficient and environmentally friendly alternative to toxic CdS for fabricating cost-effective and highly efficient Sb2Se3-based TFSCs.