Chemical Deposition Research Articles

Spray pyrolysis derived V2O5 thin films as an alternative electrochromic layer for electrochromic devices

In this study, vanadium oxide films were produced in the vanadium pentoxide (V2O5) films phase as an alternative electrochromic layer for electrochromic devices by ultrasonic spray pyrolysis technique at 300 °C. The V2O5 films were subjected to heat treatment at different temperatures (400-450-500 °C) and the ellipsometric, structural, morphological, optical and electrical properties of the films were investigated. The optical parameters of the V2O5 films were calculated by different theoretical methods and compared with the ellipsometric results. The average thickness and refractive index values are 172 nm and 2.29, respectively. The V2O5 films showed high optical absorbance in the visible region and band gap energy values ranged from 2.10 to 2.44 eV. The resistivity and roughness of the films decreased. The average roughness was determined to be 45 nm on average. These results suggest that V2O5 phase films, whose physical properties are improved by annealing without phase change, can be considered as promising electrochromic layers for electrochromic devices applications.

Adaptive temperature compensation for [formula omitted] humidity sensor in complex environments using ISSA-BP neural network

High-precision humidity detection in complex environments is essential across various fields. In this study, a high-performance MoS2 humidity sensor with a dynamic response time of less than 3 s was developed using molten salt-assisted chemical vapor deposition. To address the challenges posed by dynamic ambient temperature changes on sensor accuracy, an improved sparrow search algorithm-back propagation (ISSA-BP) neural network was constructed to mitigate temperature drift and correct nonlinear errors in the sensor output. The ISSA-BP neural network utilizes a global optimization strategy with adaptive learning, significantly enhancing accuracy and efficiency by optimizing the initialization and iterative update processes of traditional algorithms. Experimental results indicate that the proposed ISSA-BP achieves an average relative error of just 0.75% in humidity sensors across various environmental conditions, representing a 5.8-fold improvement in accuracy compared to traditional methods. Additionally, the algorithm demonstrated high robustness and accuracy across different environments, sensors, and datasets, confirming its applicability in complex and variable scenarios.

Nano-strategies for advancing oral drug delivery: Porous silicon particles and cyclodextrin encapsulation for enhanced dissolution of poorly soluble drugs

Development of novel active pharmaceutical ingredients (API) for oral use often face challenges due to low bioavailability. Nanoparticle-based drug delivery systems and cyclodextrin (CD) encapsulation offer promising solutions by enhancing API solubility or dissolution rates. Porous silicon nanoparticles have shown potential to encapsulate APIs in their amorphous form within pores, improving dissolution rates compared to crystalline counterparts. A novel synthesis approach, circumventing the expensive and tedious Si wafer material synthesis, has been developed using centrifugal Chemical Vapor Deposition (cCVD). Herein, various cCVD Si particles were evaluated for their ability to enhance the dissolution rate of the model drugs celecoxib (CEL), phenytoin (PHT), griseofulvin (GRI), diclofenac (DCF), and naproxen (NAP). Our findings demonstrate increased dissolution rates of all tested APIs when formulated with cCVD Si particles, compared to free API in pH 7.4 or pH 2.0. Particle characteristics were largely retained after loading, and the solid state of the loaded APIs were evaluated using Differential Scanning Calorimetry (DSC). Dissolution kinetics were influenced by the particle properties, mass loading and API characteristics. Loading of CD-CEL, −GRI and −DCF complexes into the cCVD Si particles showed a potential for further enhanced dissolution rates, representing the first reported investigation of this combination. In conclusion, the cCVD Si particles are promising for improving the dissolution rate of poorly soluble drugs, potentially due to precipitation of amorphous or metastable forms. Further enhancements were observed upon loading CD-drug complexes, thereby offering promising strategies for optimizing drug bioavailability

Synthesis of MnFe-C core–shell nanoparticles with tunable microwave absorption performance by designing the Mn/Fe ratio

Metal-C nanoparticles with MnFe nanocores and their microwave absorption performances with design Mn/Fe ratios have been rarely reported in previous studies. In this work, MnFe-C core–shell nanoparticles with tunable Mn/Fe ratios were prepared by a one-step metal organic chemical vapor deposition method. It was found that the magnetic properties and microwave absorption performances of the nanoparticles could be well tunable by designing Mn/Fe ratios in their nanocores. These results suggest that the as-synthesized MnFe-C core–shell nanoparticles have great potential for microwave absorption applications.

Surface Modification of Commercial YSZ with SiO2 and SnO2 via Low-Temperature Chemical Vapor Deposition to Improve Electrochemical Performance

Surface Modification of Commercial YSZ with SiO2 and SnO2 via Low-Temperature Chemical Vapor Deposition to Improve Electrochemical Performance

Chemical vapor deposition growth of large-area molybdenum disulphide (MoS2) dendrites

Molybdenum disulphide (MoS2) has emerged as a popular transition metal dichalcogenide (TMDC) in the recent decade because of its potential applications in electronic devices, optoelectronics, and fuel cells. Specifically, dendritic MoS2 has been shown to efficiently catalyse various hydrogen evolution reactions. We report the growth of dendritic MoS2 flakes on SiO2/Si wafers using a sophisticated atmospheric pressure chemical vapor deposition (APCVD) system. High-resolution optical microscopy reveals a morphology comprising different star-shaped dendrites, in addition to large MoS2 domains, which merge to form a continuous film. Our observations reveal that the dendrites originate from the nucleation centre of a monolayer MoS2 island, and their branches develop preferentially along the grain boundaries of this island. Raman spectroscopy, Atomic force microscopy (AFM), Field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS) measurements were carried out to characterize the as-grown MoS2 dendrites and further confirm these observations.

Mass balance of nickel manganese cobalt cathode battery recycle process

Batteries made from lithium, nickel, manganese, and cobalt are widely used, especially in the electrical industry, because they have high specific capacity, high safety, and low production costs. According to the International Energy Agency (IEA), the consumption of batteries used for electric vehicles will increase from 8 million in 2019 to 50 million in 2025 and to 140 million in 2030. As a result, the waste produced is also increasing. This type of lithium ion battery (LIB) which contains heavy metal elements such as nickel, manganese and cobalt can be recycled. This research aims to calculate the mass balance of the recycling process for nickel manganese cobalt (NMC) battery cathodes. The processing process begins with mixing, leaching, filtration, drying the results of the filtration process, molarity adjustment, Flame Assisted Spray Pyrolysis, and calcination. Based on the results of mass balance calculations for the NMC recycle battery cathode, the amount obtained was 43.427 kg/batch from 100 kg of cathode waste raw material. Apart from that, data was obtained on the metals that were successfully recycled, namely NiO, MnO, CoO, Fe2O3, MgO, Al2O3, Cr2O3, and Li2O. The research results provide information that NMC battery waste can be an opportunity for the NMC metal supply chain and can reduce environmental pollution.

Fabrication of C and N co-doped CdS semiconductor photocatalysts derived from a novel Cd-MOF for enhancing photocatalytic performance

The narrow bandgap value and long lifetime of photo generated charges make CdS exhibit higher photocatalytic activity compared to other semiconductor catalysts. Given the excellent optoelectronic properties of CdS, a novel 2D cadmium-organic framework (Cd-MOF) was obtained by solvothermal method, which was served as a precursor template in this paper. C and N co-doped CdS-T (T = 600/800/1000) semiconductor materials were successfully prepared by chemical deposition method under different high temperatures. The as-prepared materials had been characterized in detail. Furthermore, the Cd-MOF and CdS-T were used to conduct the photocatalytic activity of organic dyes. Among them, CdS-800 showed excellent photocatalytic degradation effects on five organic dyes, especially on RB with the photocatalytic degradation efficiency of 98.87 %, which was significantly improved 6.5 times compared to Cd-MOF (58.23 %). Free radical capture experiments have shown that •O2− play a dominant role in the photocatalytic process. In addition, UV–vis diffuse reflection, photoluminescence (PL), photoelectrochemical (PEC) testing and density functional theory (DFT) calculations had shown that CdS-800 could effectively delay the recombination of photo generated charges, improve the rapid migration and separation of photo generated carriers, and enhance photocatalytic activity. This work provides new ideas for the preparation of efficient and recyclable CdS semiconductor photocatalytic materials.

Scalable approach for growing hexagonal boron nitride on silicon and its role in III-nitride van der Waals epitaxy

Hexagonal boron nitride (h-BN) stands out among 2D materials for its insulating properties, making it promising for the integration of 2D and 3D materials. However, achieving wafer-scale growth on silicon substrates remains a significant challenge. In this study, growth strategies for depositing h-BN on Si substrates are explored utilizing the wafer scalable metalorganic chemical vapor deposition. Our investigations reveal that employing a pulsed flow mode scheme is preferable over the conventional continuous flow mode scheme in growing h-BN thin films on 150 mm Si substrates. The as-grown h-BN film on Si exhibits uniform coverage with h-BN[0001]//Si[111]. With the successful wafer-scale growth of h-BN on Si, its role in aiding the van der Waals epitaxy of III-nitrides on Si substrates and subsequent epitaxial lift-off (ELO) of III-nitrides is further exemplified. An optimized h-BN thickness for the ELO process is also determined.

Construction and Multifunctional Photonic Applications of Light Absorption-Enhanced Silicon-Based Schottky Coupled Structures.

To expand the detection capabilities of silicon (Si)-based photodetector and address key scientific challenges such as low light absorption efficiency and short carrier lifetime in Si-based graphene photodetector. This work introduces a novel Si-based Schottky coupled structure by in situ growth of 3D-grapheneand molybdenum disulfide quantum dots (MoS2 QDs) on Si substrates using chemical vapor deposition (CVD) and plasma-enhanced chemical vapor deposition (PECVD) techniques. The findings validate the "dual-enhanced absorption" effect, enhancing the understanding of the mechanisms that improve optoelectronic performance. The synergistic effect of 3D-graphene's natural nano-resonant cavity and MoS2 QDs enhances light absorption efficiency and extends carrier lifetime. Introducing MoS2 QDs broadens and intensifies the built-in electric field, promoting the separation of photogenerated electrons and holes. The photodetector exhibits a wideband light response in the wavelength range of 380-2200nm. It stably outputs photocurrent under high-frequency (1 kHz) modulated laser (2200nm), with a responsivity (R) of 40mAW-1 and detectivity (D*) of 1.15×109 Jones. Photodetectors show the ability to process and encrypt complex binary signals and achieve versatility in "AND" gate and "OR" gate logic operations, as well as image sensing (240×200 pixels).

Rapid Scalable One‐step Production of Catalysts for Low‐Iridium Content Proton Exchange Membrane Water Electrolyzers

AbstractProton exchange membrane water electrolysis (PEMWE) is a promising technology for green hydrogen production, although its widespread development with state‐of‐the‐art loadings is threatened by the scarcity of iridium (Ir). Homogeneous dispersion of Ir in an immiscible electro‐ceramic matrix can enhance catalytic mass activity and structural stability. The study presents IrySn0.9(1−y)Sb0.1(1−y)Ox solid solutions produced by highly scalable flame spray pyrolysis (FSP) process as efficient anode electrocatalysts for PEMWE, containing only 0.2 mg cm−2 of Ir in the catalyst layer (CL). Intense mixing of metal vapor and large thermal gradients in the precursor‐derived high‐temperature flame aids stabilizing sub‐nanoscale entropic mixing within self‐preserved 4–6 nm particles. Detailed investigations confirm that the one‐step prepared solid solution electrocatalysts exhibit up to fourfold higher activity toward the oxygen evolution reaction (OER) compared to Ir black. The anode of a PEMWE utilizing this catalyst exhibits high performance and stability over 2000 h but with tenfold lower Ir loading than the state‐of‐art.

Fabrication of 0.6 eV Bandgap In0.69Ga0.31As Thermophotovoltaic Cells and Its System Demonstration

Thermophotovoltaic (TPV) is a promising energy conversion technology that can absorb the heat from a thermal radiator and transfer it into power. As the most significant energy converter, TPV cells need a narrower bandgap to realize a wider absorption spectrum range. In this work, the fabrication and characterization of single‐junction In0.69Ga0.31As TPV cells with a bandgap of 0.6 eV are presented. The main structure is grown on an InP substrate through metal‐organic chemical vapor deposition. Step‐graded InAsyP1−y buffer layers are used to mitigate the dislocations by relaxing the stress induced by lattice mismatch completely. Analysis of the composition, strain relaxation, layer tilt, and crystalline quality of each layer is demonstrated using triple‐axis X‐ray reciprocal space mapping and transmission electron microscopy. According to the tested results, each layer is found to be nearly fully relaxed and the InGaAs active layer grown on the buffer displays a high crystal quality. External quantum efficiency achieves 90% at 1100–1500 nm. Additionally, a TPV test platform is constructed to evaluate the cell performance. The maximum efficiency of the lattice‐mismatched TPV cell reaches 21.92% operating at a power density of 267.4 mW cm−2 and an emitter temperature of 1200 °C.

Two-Step Chemical Vapor Deposition for Fabrication of FAPbI3 Single-Crystal Microsheets with High Exciton Binding Energy.

Hybrid perovskites exhibit highly efficient optoelectronic properties and find widespread applications in areas such as solar cells, light-emitting diodes, photodetectors, and lasers. Here, we report the innovative synthesis of formamidinium lead iodide (FAPbI3) single-crystal microsheets via a two-step chemical vapor deposition (CVD) method. The microsheets exhibit hexagonal and trapezoidal shapes, with hexagonal FAPbI3 growing parallel to the substrate and trapezoidal FAPbI3 growing perpendicular to the substrate. The dominant role of single-exciton recombination in the photoluminescence (PL) of these microsheets is observed, especially pronounced at low temperatures, attributed to the relatively large exciton binding energies of the samples. Calculations reveal exciton binding energies as high as 110.8 meV for hexagonal and 133.3 meV for trapezoidal FAPbI3 single-crystal microsheets, attributed to reduced rotational freedom of the formamidinium (FA) ions. Further investigation into low-temperature phase transitions indicates lower transition temperatures (around 100 K) for these microsheets, suggesting reduced FA ion rotational freedom and consequently higher exciton binding energies.

Passively generated Q-switched pulses fiber laser in 2 μm wavelength using MXene Ti3C2Tx and Ti2CTx saturable absorber

Abstract In this paper, Q-switched Thulium-doped fiber lasers (TDFLs) operating near the 2 µm region were demonstrated, utilizing a newly developed Thulium doped fiber as the gain medium and titanium carbide MXene as the saturable absorber (SA). The Thulium-doped fiber with a composition of SiO2-GeO2-Al2O3-HfO2-Y2O3-Bi2O3, was produced from a preform prepared using the modified chemical vapor deposition (MCVD) process. Two variations of titanium carbide MXene-based SA, Ti3C2Tx and Ti2CTx, were tested and compared, both successfully generating Q-switched pulses. When Ti3C2Tx was used, the Q-switched pulse had a center wavelength of 1934.223 nm, a repetition rate of 55.39 kHz and a pulse width and 1.942 µs. For Ti2CTx, the generated Q-switched pulse has a center wavelength of 1932.229 nm, with a repetition rate of 77.28 kHz and a pulse width of 1.608 µs. The signal-to-noise ratio (SNR) values were 45.6 dB and 50.2 dB for Ti3C2Tx and Ti2CTx respectively. Based on the experimental results, both Ti3C2Tx and Ti2CTx show promise as SAs for generating Q-switched pulses in the 2 µm region within the TDFL cavity.

Stabilizing Metal Halide Perovskite Films via Chemical Vapor Deposition and Cryogenic Electron Beam Patterning.

Halide perovskites are hailed as semiconductors of the 21st century. Chemical vapor deposition (CVD), a solvent-free method, allows versatility in the growth of thin films of 3- and 2D organic-inorganic halide perovskites. Using CVD grown methylammonium lead iodide (MAPbI3) films as a prototype, the impact of electron beam dosage under cryogenic conditions is evaluated. With 5 kV accelerating voltage, the dosage is varied between 50 and 50000 µC cm-2. An optimum dosage of 35 000 µC cm-2 results in a significant blue shift and enhancement of the photoluminescence peak. Concomitantly, a strong increase in the photocurrent is observed. A similar electron beam treatment on chlorine incorporated MAPbI3, where chlorine is known to passivate defects, shows a blue shift in the photoluminescence without improving the photocurrent properties. Low electron beam dosage under cryogenic conditions is found to damage CVD grown 2D phenylethlyammoinum lead iodide films. Monte Carlo simulations reveal differences in electron beam interaction with 3- and 2D halide perovskite films.

Realizing 0.7 dB/m gain in O + E band by promoting BACs-P formation in bismuth-doped phosphosilicate fiber with double-pass configuration.

The long fiber length required for the amplification of bismuth-doped fiber (BDF) has hindered its practical application. In this paper, we propose and demonstrate a feasible method to improve the active absorption of bismuth active centers (BACs) by optimizing the drawing conditions, achieving a high gain with a short fiber length. The bismuth-doped phosphosilicate fiber (BPSF) preform was fabricated by the modified chemical vapor deposition (MCVD) process and drawn into fiber under nine different conditions. The results indicate that the active absorption of BACs increases as the drawing temperature increases and the drawing speed decreases within these drawing parameters. Meanwhile, the corresponding gain per unit length is improved. Furthermore, a maximum gain of 31.6 dB at 1350 nm with the >20 dB gain wavelength range of 1311-1401 nm was achieved in a double-pass double-pump configuration, using only 45 m BPSF. Meanwhile, the -3 dB bandwidth was 1328-1370 nm. The gain per unit length is 0.7 dB/m, which, to the best of our knowledge, is the highest gain per unit length reported for the BPSF.

Nanocrystalline Lanthanum Oxide Layers on Tubes Synthesized Using the Metalorganic Chemical Vapor Deposition Technique

Lanthanum oxide (La2O3) layers are widely used in electronics, optics, and optoelectronics due to their properties. Lanthanum oxide is also used as a dopant, modifying and improving the properties of other materials in the form of layers, as well as having a large volume. In this work, lanthanum oxide layers were obtained using MOCVD (Metalorganic Chemical Vapor Deposition) on the inner walls of tubular substrates at 600–750 °C. The basic reactant was La(tmhd)3 (tris(2,2,6,6-tetramethyl-3,5-heptanedionato)lanthanum(III)). The evaporation temperature of La(tmhd)3 amounted to 170–200 °C. Pure argon (99.9999%) and air were used as the carrier gases. The air was also intended to remove the carbon from the synthesized layers. Tubes of quartz glass were used as the substrates. La2O3 layers were found to be growing on their inner surfaces. The value of the extended Grx/Rex2 criterion, where Gr—Grashof’s number, Re—Reynolds’ number, x—the distance from the gas inflow point, was below 0.01. The microstructure of the deposited layers of lanthanum oxide was investigated using an electron scanning microscope (SEM). Their chemical composition was analyzed via energy-dispersive X-ray (EDS) analysis. Their phase composition was tested via X-ray diffraction. The transmittance of the layers of lanthanum oxide was determined with the use of UV-Vis spectroscopy. The obtained layers of lanthanum oxide were characterized by a nanocrystalline microstructure and stable cubic structure. They also exhibited good transparency in both ultraviolet (UV) and visible (Vis) light.

Comparison of ZnO Nanoparticles Prepared by Spray Pyrolysis and Consecutive Method for UV-Driven Photocatalytic Degradation of Methylene Blue

ZnO is a semiconductor material that is widely used for many applications in industries such as solar cells, dye-sensitized solar cells, food packaging, photocatalytic, anti-microbial, light-emitting diode devices, and gas sensors. In this study, ZnO nanoparticles (NPs) have been successfully synthesized using two methods, namely spray pyrolysis and a consecutive method. The consecutive method is a combination of sol-gel and spray drying methods. The objective of this study is to investigate the photocatalytic performance of ZnO fabricated using those methods. Both methods used the same precursor, zinc acetate dehydrate as a source of zinc, but with different solvents and additives. Based on the X-ray diffraction pattern, the ZnO NPs synthesized using spray pyrolysis and a consecutive method exhibited similar polycrystalline hexagonal wurtzite structures. The large crystal sizes of ZnO NPs were obtained using a consecutive method, sol-gel followed by spray drying, in comparison with those from the ZnO spray pyrolysis. In contrast, the particle size of ZnO prepared by the consecutive method was in a smaller range. The SEM analysis implied that the ZnO structures had surface defects. In the UV-driven photocatalytic degradation of methylene blue, ZnO produced by the consecutive method exhibited slightly higher degradation performance than ZnO spray pyrolysis. This performance was attributed to the larger crystal size of ZnO NPs, which provided a longer carrier movement at semiconductor surfaces and reduced electron-hole recombination. Additionally, ZnO NPs produced using the consecutive method underwent agglomeration that leads to a smaller contact surface with methylene blue, obstructing the degradation process.

Ultraviolet Laser Activation of Phosphorus‐Doped Polysilicon Layers for Crystalline Silicon Solar Cells

AbstractIn crystalline silicon photovoltaics (c‐Si PV), a pulsed laser can be used as a substitute for a high‐temperature furnace dopant diffusion/activation step. In contrast to furnace‐based activation, lasers can be used to achieve highly localized doping with controlled dopant concentrations, useful in advanced architectures such as the interdigitated back contact (IBC) solar cell. In this study, a pulsed ultraviolet (UV) laser is utilized for phosphorus dopant activation within a low‐pressure chemical vapor deposited (LPCVD) polycrystalline silicon (poly‐Si) passivated contact layer. The highest implied open‐circuit voltage iVoc values achieved using this approach reach 726 mV. However, this comes at the expense of high specific contact resistivities ρc, which is attributed to a lower dopant concentration across the poly‐Si(n+)/SiOx/c‐Si interface. Regardless, the optimum iVoc, ρc combination is measured at a laser fluence of 0.78 J cm−2 producing values of 712 mV and 89 mΩ‐cm2, respectively. These values are still compatible with high‐efficiency solar cell designs, underscoring the feasibility and effectiveness of this approach.

Hydrogen‐Driven Phase Differentiation in BN Nucleation on Diamond

AbstractBoron nitride has attracted scientific interest in recent years due to its potential use in electronics, both as hexagonal (hBN) and cubic (cBN) phases. While both are successfully realized through chemical vapor deposition, the heteroepitaxial growth of cBN on another iconic semiconductor, diamond is plagued with mixed‐phase formation. Employing first‐principles computations and a nanoreactor approach, the BN phase preferences are explored on diamond (001) controlled—as it is discovered—by the hydrogen gas concentration. In a limited‐hydrogen environment, the initial BN‐island expands along the diamond surface, forming a 3D metastable cubic phase that grows in the direction normal to the basal plane through kinetically‐limited nucleation, thus overcoming the thermodynamic preference toward the hBN phase. Comparatively, the amorphous phase is favored in the absence of hydrogen, while the hexagonal phase dominates at its high levels, elucidating numerous experimental observations. A obtained kinetic phase diagram connects the phase with hydrogen chemical potential to facilitate targeted phase selection. The results suggest that gas‐mediated nucleation kinetics provide feasible control for the precise synthesis. It also offers valuable guidance for the controllable synthesis of desired BN phases and advances research toward potential BN electronics.