Deposition Of Metal Oxides Research Articles

Study of molecular layer deposition of zinc-based hybrid film as photoresist

Molecular layer deposition (MLD) of metal oxide and organic hybrid thin films has great potential to be utilized in extreme ultraviolet photoresist, thanks to its excellent uniformity on the nanometer scale thickness control. Zn has large photoelectron effect cross-section, resulting in lots of secondary electrons, which can break the organic bonds, causing changes in solubility upon the ultraviolet (UV) light exposure. In this work, Zn-based MLD thin films have been demonstrated for their potential to be used as photoresist for extreme ultraviolet(EUV) application. UV light exposure mechanisms have been proposed based on X-ray photoelectron spectroscopy(XPS) analysis.

Preparation of Br-terminated Si(100) and Si(111) surfaces and their use as atomic layer deposition resists

In area-selective processes, such as area-selective atomic layer deposition (AS-ALD), there is renewed interest in designing surface modification schemes allowing to tune the reactivity of the nongrowth (NG) substrates. Many efforts are directed toward small molecule inhibitors or atomic layers, which would modify selected surfaces to delay nucleation and provide NG properties in the target AS-ALD processes allowing for the manufacturing of smaller sized features than those produced with alternative approaches. Bromine termination of silicon surfaces, specifically Si(100) and Si(111), is evaluated as a potential pathway to design NG substrates for the deposition of metal oxides, and TiO2 (from cycles of sequential exposures of tetrakis-dimethylamido-titanium and water) is tested as a prototypical deposition material. Nucleation delays on the surfaces produced are comparable to those on H-terminated silicon that is commonly used as an NG substrate. However, the silicon surfaces produced by bromination are more stable, and even oxidation does not change their chemical reactivity substantially. Once the NG surface is eventually overgrown after a large number of ALD cycles, bromine remains at the interface between silicon and TiO2. The NG behavior of different crystal faces of silicon appears to be similar, albeit not identical, despite different arrangements and coverage of bromine atoms.

Effect of Metal Oxide Deposition on the Sensitivity and Resolution of E-Beam Photoresist.

Organic-inorganic hybrid resists offer a solution to the issue of low sensitivity in organic photoresists like poly(methyl methacrylate) (PMMA). In this study, an organic-inorganic hybrid resist (PMMA-Al2O3) with high sensitivity and resolution was prepared by depositing metal oxides into PMMA using sequential infiltration synthesis (SIS). PMMA-Al2O3 was prepared by precisely controlling the number of SIS cycles (<23) in various atomic layer deposition (ALD) processes to facilitate the growth of metal oxides within PMMA pores. The impact of different metal oxide contents and distributions on the sensitivity and resolution of electron beam exposure was investigated. Numerical simulations of the deposit formation within the PMMA pores were performed by solving the pore-scale ALD governing equations fed by the reactor-scale boundary conditions. The gradual pore constriction with SIS cycles was predicted and validated by the experimental charaterizations. The results demonstrated that PMMA-Al2O3 was prepared using 20 SIS cycles, which corresponds to the numerically predicted occurrence of the pore blockage at the upper region of the PMMA layer, exhibiting optimal electron beam (e-beam) resolution while enabling line exposure with a width of 50 nm. While the corresponding sensitivity was lower than those of the samples prepared using 5 and 10 SIS cycles, the degradation of the PMMA structure was affected under exposure. The pattern transfer results showed that the line width was well retained for 20 cycles of deposition because of the high etching resistance of Al2O3. This research is expected to provide an effective approach to developing next-generation high-performance photoresists.

Exploring the machined surface characteristics of Haynes 25 superalloy: Cost mitigation and quality enhancement perspective

The current study investigates the surface characteristics and machining cost of electrical discharge machining (EDM) of Haynes 25 superalloy using tools made by additively manufactured CuCr1Zr, pure copper and graphite. Before assessing machinability, the workpiece and tool materials were characterized using Energy Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD) and evaluations of tensile strength, micro-hardness, density and thermal conductivity. The effects of current (I), voltage (V), pulse duration (Ton), duty cycle (τ) and flushing pressure (Fp) is analyzed on surface characteristics viz. surface roughness (SR), surface crack density (SCD), recast layer thickness (RCT), heat-affected zone (HAZ), micro-hardness (MH) and machining cost (MC). Post machining XRD analysis revealed the formation of cobalt oxides like (CoO and Co3O4) affecting the micro-hardness of the machined surface. Alongside, a field emission scanning electron microscopy (FESEM) is carried out which confirms, the deposition of metal carbides and oxides on the EDMed surface. Current and pulse-on-time significantly influenced performance, with optimal EDM parameters identified and validated through confirmative experiments, resulting in a mean error of ∼2.84 %. It is seen that the use of additively manufactured CuCr1Zr tools resulted in improved machined surface characteristics and a more cost-effective approach for producing intricate profiles with minimal surface defects.

MALDI target functionalization with deposited thin films of lanthanum stearate – An efficient tool for in situ enrichment of human globin adducts of chlorinated organic compounds

“Lab-on-a-plate” methodology encapsulates a number of different approaches aimed to shorten extensive sample processing for matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) analysis. Lately, we have proposed two approaches to the enrichment of chlorine-containing adducts of human globin (HHb) in a “lab-on-a-plate” format based on different techniques for the sorbent application to MALDI target spots: (i) droplet-free electrospraying of metal oxide nanoparticles and (ii) deposition of lanthanum stearate thin films (FLa). The latter approach has turned out to be more time- and cost-effective and, therefore, seems to be more promising. In this work, we assessed the quantitative characteristics (sensitivity, selectivity) of the “thin-film” procedure in order to estimate its analytical potential. The FLa-modified MALDI target was used for the on-spot enrichment of HHb adducts from the tryptic digests of the protein incubated with two model mono- and dichlorine-containing alkylating agents. The sensitivity of the technique is in the range of hundreds of fmol. Furthermore, the FLa-based procedure shows high selectivity (maximum molar ratio of modified/unmodified form of LLGNVLVC112VLAHHFGK is 1:500). As a case study, on-plate extraction of HHb adducts, formed due to the interaction of the protein with in vitro generated diclofenac metabolites, was performed on FLa-functionalized spots. This resulted in specific extraction of the HHb adducts with two diclofenac oxidation products from the tryptic digest of modified HHb. The developed approach appears to be effective for in situ enrichment of chlorine-containing adducts of HHb.

Fully atomic layer deposition induced InAlO thin film transistors

The atomic layer deposition (ALD) technique has been extensively utilized for depositing metal oxide (MO) thin films, particularly as gate insulators in thin film transistors (TFTs). However, research on MO semiconductors as channel layer materials in TFTs using ALD is limited, especially for fully ALD-fabricated MO TFTs. In this study, fully ALD-fabricated InAlO TFTs were developed, with optimized aluminum doping content and annealing temperature to enhance the electrical properties and stability. The InAlO TFTs, fabricated with a cycle ratio of 15:1 and annealed at 350 °C, exhibit superior performance, including a field-effect mobility of 7.2 cm2/V·s, a subthreshold swing of 165 mV/decade, and an on/off current ratio of 2.3 × 106, with a threshold voltage of only 0.1 V. Additionally, they demonstrated good stability, with a threshold voltage shift of 0.11 V under positive bias stress. The improved electrical properties and stability are attributed to reduced carrier concentration and the inhibition of oxygen defect generation, achieved through appropriate annealing temperatures and aluminum doping. Thus, the development of fully ALD-fabricated high-performance TFTs holds promise for next-generation display technologies as pixel-driving circuits.

Dry Deposition and Dry Development of Metal Oxide Based Photoresist

Dry Deposition and Dry Development of Metal Oxide Based Photoresist

Non-destructive buffer enabling near-infrared-transparent inverted inorganic perovskite solar cells toward 1400 h light-soaking stable perovskite/Cu(In,Ga)Se2 tandem solar cells

Near-infrared (NIR) transparent inverted all-inorganic perovskite solar cells (PSCs) are excellent top cell candidates in tandem applications. An essential challenge is the replacement of metal contacts with transparent conductive oxide (TCO) electrodes, which requires the introduction of a buffer layer to prevent sputtering damage. In this study, we show that the conventional buffers (i.e., small organic molecules and atomic layer deposited metal oxides) used for organic-inorganic hybrid perovskites are not applicable to all-inorganic perovskites, due to non-uniform coverage of the vulnerable layers underneath, deterioration upon ion bombardment and moisture induced perovskite phase transition. A thin film of metal oxide nanoparticles by the spin-coating method serves as a non-destructive buffer layer for inorganic PSCs. All-inorganic inverted near-infrared-transparent PSCs deliver a PCE of 17.46% and an average transmittance of 73.7% between 780 and 1200 nm. In combination with an 18.56% Cu(In,Ga)Se2 bottom cell, we further demonstrate the first all-inorganic perovskite/CIGS 4-T tandem solar cell with a PCE of 24.75%, which exhibits excellent illumination stability by maintaining 86.7% of its initial efficiency after 1400 h. The non-destructive buffer lays the foundation for efficient and stable NIR-transparent inverted inorganic perovskite solar cells and perovskite-based tandems.

Parameters Optimization for Electrophoretic Deposition of Mn1.5Co1.5O4 on Ferritic Stainless Steel Based on Multi-Physical Simulation

Solid oxide fuel cells (SOFCs) are an effective and sustainable energy conversion technology. As operating temperatures decrease, metal interconnects and supports are widely employed in SOFCs. It is critical to apply a protective coat on ferritic stainless steel (FSS) to suppress Cr evaporation and element interdiffusion under high temperatures. Electrophoretic deposition (EPD) is a promising approach for depositing metal oxides on FSS substrate. Here, a method based on 3D multi-physical simulation and orthogonal experimental design was proposed to optimize deposition parameters, including applied voltage, deposition time, and electrode distance. The EPD process to deposit Mn1.5Co1.5O4 particles in a suspension of ethanol and isopropanol was simulated and the effects of these three factors on the film thickness and uniformity were analyzed. The results indicate that applied voltage has the greatest impact on deposition thickness, followed by deposition time and electrode distance. Meanwhile, deposition time exhibits a more significant effect on film unevenness than applied voltage. Additionally, the particle-fluid coupling phenomenon was analyzed during the EPD process. In practice, these deposition parameters must be selected appropriately and the deposition time must be controlled to obtain a uniform coating. The proposed method can reduce cost and shorten the design period.

Towards sustainable solar cells: unveiling the latest developments in bio-nano materials for enhanced DSSC efficiency

Abstract Fossil fuels—instrumental in powering the nineteenth-century Industrial Revolution—are now under heightened scrutiny due to environmental concerns and carbon emissions. Consequently, there is a global impetus towards achieving carbon-neutral energy production, with solar energy emerging as a cornerstone in this transition. Over the past three decades, dye-sensitized solar cells (DSSCs) have gained increasing prominence due to their unique advantages. This review elucidates several crucial elements essential to DSSC construction, notably bio-nano materials, prized for their structural flexibility, cost-effectiveness and high molar absorption coefficient. It delves into the intricate relationship between molecular structure and DSSC performance, showcasing significant advancements with light-to-power conversion efficiencies reaching 11%. A comprehensive analysis of the photovoltaic performance of DSSCs utilizing bio-nano-based dyes offers invaluable insights into the state of this rapidly evolving industry. Key components under scrutiny include transparent conductive oxide (TCO) layers, physical techniques for metal oxide deposition onto TCO thin films, diverse dye variants and foundational knowledge of components ripe for growth and enhancement. Moreover, the review outlines the latest breakthroughs in the field, providing glimpses into the current status of prototype DSSCs.

One‐Step Synthesis and Deposition of Metal Oxides: NiO Quantum Dots as a Transport Layer for Perovskite Photovoltaics

One‐step synthesis and deposition of nickel oxide quantum dots using a gas‐phase microplasma process is demonstrated and their applicability as a transport layer for solar cell devices is shown. The process uses a solid nickel metal wire as sacrificial electrode, and the concentration of oxygen gas required in the synthesis is investigated. The quantum dots are characterized for physical, chemical, and optical properties and critical process parameters such as the process throughput are also estimated. Direct one‐step deposition directly on perovskite solar cells is carried out using a computer‐controlled x–y stage and the performance of the solar cell device is assessed.

Influence of chemistry and topography on the wettability of copper

To understand the complex interplay of topography and surface chemistry in wetting, fundamental studies investigating both parameters are needed. Due to the sensitivity of wetting to miniscule changes in one of the parameters it is imperative to precisely control the experimental approach. A profound understanding of their influence on wetting facilitates a tailored design of surfaces with unique functionality.We present a multi-step study: The influence of surface chemistry is analyzed by determining the adsorption of volatile carbonous species (A) and by sputter deposition of metallic copper and copper oxides on flat copper substrates (B). A precise surface topography is created by laser processing. Isotropic topography is created by ps laser processing (C), and hierarchical anisotropic line patterns are produced by direct laser interference patterning (DLIP) with different pulse durations (D).Our results reveal that the long-term wetting response of polished copper surfaces stabilizes with time despite ongoing accumulation of hydrocarbons and is dominated by this adsorption layer over the oxide state of the substrate (Cu, CuO, Cu2O). The surfaces’ wetting response can be precisely tuned by tailoring the topography via laser processing. The sub-pattern morphology of primary line-like patterns showed great impact on the static contact angle, wetting anisotropy, and water adhesion. An increased roughness inside the pattern valleys combined with a minor roughness on pattern peaks favors air-inclusions, isotropic hydrophobicity, and low water adhesion. Increasing depth of the primary topography can also induce air-inclusions despite increasing peak roughness while time dependent wetting transitions were observed.

Dopamine Sulfonate Ligand-Assisted TiO2 Deposition Enabling Highly Efficient and Stable Perovskite Solar Cells.

The metal oxide electron transport layers (ETLs) with flat morphology and high electrical quality are essential to manufacture highly efficient perovskite solar cells (PSCs), in which the regulation of the metal oxide deposition process plays a crucial role. Herein, a judiciously designed dopamine sulfonate (DS) ligand-assisted deposition of titanium dioxide (TiO2) films approach is implemented based on electrostatic repulsion and steric hindrance of assembled ligands to improve colloidal nanoparticles dispersity in precursor and effectively inhibit their aggregation, which could enable obtaining smooth topography of TiO2 films and initiating growth of top high-quality perovskite films. Furthermore, sulfonate bridges bonded on the perovskite buried layer that is beneficial to form better buried interface contact and accelerate electron extraction. As a result, the PSCs employing DS/TiO2 ETLs exhibit the best power conversion efficiency of 24.53% with impressive storage stability and operation stability, i.e., remaining more than 88% of their initial efficiency upon storage N2 glovebox without encapsulation over 4000 h, and the efficiency does not attenuate significantly under maximum power point for 60 h.

Interface defect formation for atomic layer deposition of SnO2 on metal halide perovskites

With the rapidly advancing perovskite solar cell (PSC) technology, dedicated interface engineering is critical for improving device stability. Atomic layer deposition (ALD) grown metal oxide films have drawn immense attention for the fabrication of stable PSC. Despite the advantages of ALD, the deposition of metal oxides directly on bare perovskite has so far not been achieved without damaging the perovskite layer underneath. In addition, the changes to the physicochemical and electronic properties at the perovskite interface upon exposure to the ALD precursors can alter the material and hence device functionality. Herein, we report on a synchrotron-based hard X-ray photoelectron spectroscopy (HAXPES) investigation of the interface between metal halide perovskite (MHP) absorber and ALD-SnO2 electron transport layer. We find clear evidence for the formation of new chemical species (nitrogen compound, lead dihalides) and an upward band bending in the MHP and downward band bending in the SnO2 towards the MHP/ALD-SnO2 interface. The upward bending at the interface forms an electron barrier layer of ∼400 meV, which is detrimental to the PSC performance. In addition, we assess the effectiveness of introducing a thin interlayer of the organic electron transport material Phenyl-C61-butyric acid methyl ester (PCBM) between MHP and ALD-SnO2 to mitigate the effects of ALD deposition.

Incorporation of Cu and Mn ions into hydroxyapatite channels and deposition of complex metal oxide

The Cu-and Mn-incorporated apatite-type phosphate, Ca10(PO4)6CuxMny(O,OH)2, was successfully synthesized by heating the hydroxyapatite under N2 at 900 °C after Cu- and Mn-nitrate aqueous solution loading with x = 0–0.2 and y = 0–0.2 onto it. In Ca10(PO4)6Cu0·2Mn0·2(O,OH)2, Cu occupies the apatite channel center site, and the Mn site shifts from the center. The deposition of Cu and Mn species was found to occur upon heating Cu0·2Mn0.2-Ca-HAp at 600–800 °C in air, accommodating the spinel-type complex metal oxide, (Cu, Mn)3O4 formation from the apatite channel. In addition, the CuO deposition from the Ca10(PO4)6Cu0·2(O,OH)2 apatite was observed for samples heated at 600–800 °C, whereas Mn3O4 was observed for the Ca10(PO4)6Mn0·2(O,OH)2 sample heated at 800 °C. These results suggest that the presence of Cu in the apatite channel facilitates the deposition of Mn species.

Additive-free electroless deposition on graphene/copper foil: Photo-induced and defect-assisted approach for environmentally friendly plating

The environmental toxicity of chemicals used in electroless plating process is often overlooked. In fact, the wastewater from the electroless plating process contains metal complexes, reducing agents and stabilizers that can create hazard to our environment. To address this concern, an additive-free electroless deposition process on graphene/Cu foil is proposed. The defect structure of graphene plays a pivotal role by acting as a reservoir for concentrating photoelectrons generated from ultra-thin cuprous oxide (Cu2O) located at the interface of graphene and Cu foil upon exposure to light irradiation. In the Cu ion solution, Cu ions were anchored on the defect sites and formed a Cu-C4 structure with graphene. The Cu-C4 sites accumulate abundant photoelectrons and trigger the reduction of Cu ions to form island-like growth of Cu, which immediately was oxidized to Cu2O, leaving only a small portion of metallic Cu. Concurrently, the presence of Cu ions induces the generation of additional defect sites on graphene, providing further growth sites for Cu deposition. This process continues until the entire graphene surface is covered by the deposited Cu2O. Ultimately, the deposition of metallic oxides with lower redox potential can be achieved. The proposed deposition mechanism assisted by irradiation of photocatalyst and defect structure of graphene material provides a truly environmentally friendly electroless plating process. By eliminating the need for additives and significantly reducing the environmental hazards associated with electroless plating, this method holds great promise for sustainable materials manufacturing.

Co–Fe–oxide nanoparticles supported on the various highly dispersed matrices: the effect of the carrier on structural and magnetic properties

sA series of mixed oxides was synthesized by deposition of the guest phase on the highly dispersed oxide matrix. Fumed nanooxides SiO2, Al2O3, SiO2/Al2O3, and SiO2/Al2O3/TiO2 with the specific surface area of 65–91 m2/g were selected as highly dispersed matrices. Co–Fe mixed oxides with the general formula Co4xFexOy (Co: Fe = 4: 1) were deposited as the guest oxides using the two-step method: (i) solvate-stimulated modification of the surface of fumed nanocarriers with the mixture of cobalt nitrate (II) and iron (III) formate and (ii) subsequent heat treatment up to 600 °C to form Co4xFexOy. The aim of this paper was to study the influence of the composition and structure of fumed oxide matrices and deposited guest phase on the morphology of the resulting composites in the gaseous and aqueous media using the XRD, XPS, FTIR, nitrogen adsorption and SEM/EDX, as well as quasi-elastic light scattering (QELS) methods. The low-temperature nitrogen adsorption isotherms have a sigmoidal shape with a narrow hysteresis loop characteristic of mesoporous materials. The specific surface area (SBET) of the composites varies from 48 to 82 m2/g, showing a tendency towards a decrease in the SBET values by 10–26% in comparison with the initial nanocarriers. The SEM data show the denser aggregate structure of nanocomposites compared to the initial carriers. The primary particle size was in the 30–60 nm range and the EDX data confirm the formation of a guest phase on the mixed aluminosilicate carriers, mainly in the surface patches corresponding to the alumina structure. According to the QELS data, there is a tendency to form aggregates of 100–10 μm in size in the aqueous media. The XRD method shows that the deposited metal oxides are in the form of crystalline phases of Co3O4 with the crystallites of 25–26 nm in size for the individual SiO2 and Al2O3 nanocarriers and 34–37 for the mixed ones, but the iron oxide reflections were not identified for the composites. XPS observation demonstrates the signal of Fe 2p electrons as the form of Fe2O3 oxide in the surface layer of nanocomposites as well as Co 2p as the Co3O4 and Co(OH)2.

Film Deposition of Electrochromic Metal Oxides through Spray Coating: A Descriptive Review

Electrochromism induces reversible changes of coloration in specific organic and inorganic materials through electrical charge/discharge reactions. When processed into thin films, electrochromic metal oxides can be integrated into glazing applications such as displays, rearview mirrors, goggles and, most notably, smart windows in energy-efficient buildings. Over the years, the use of spray coating as a liquid-based approach has been acknowledged for its cost-efficient, high-throughput samples production with a low volume consumption. It represents an interesting alternative to vacuum processes and to other wet methods, suitably responding to the current limitations of electrochromic thin films production by offering improved control over deposition parameters and capacities of up-scaling, together with lowered energetic and economic costs. The present review summarizes the main theoretical and practical aspects of spray coating, notably distinguishing room-temperature methodologies from pyrolysis-based, under heating protocols. The main families of functional electrochromic metal oxides are then screened and discussed, establishing how spray processing can challengingly lead to higher levels of optical contrast, commutation kinetics, coloration efficiency and cycling durability, and how low-toxic and environment-friendly precursors can be favored while sustaining large deposition areas.

Spray deposited pristine and Mo doped WO3 thin films for acetaldehyde gas sensing at room temperature

In this paper, pure WO3 and molybdenum-incorporated WO3 were directly deposited in the form of thin films on the glass substrate. The films were deposited through the spray pyrolysis technique, and their gas sensing properties, structural, optical, electrical, and morphological properties were altered by adding a dopant to the pristine WO3. A direct, one-step approach is used to deposit metal oxide semiconductor materials as thin films, which enhances the ability to detect gas. A novel gas sensing response for acetaldehyde gas detection was observed from Molybdenum doped WO3 thin film at 25 °C. On investigating the sensing performance of both films for various volatile organic compounds (VOC), a high response (54.55 %) towards acetaldehyde was achieved for 2 % molybdenum-doped WO3 film. The XRD analysis demonstrated that the synthesized films are crystalline with triclinic phase. Decrease in crystallite size increases the grain boundaries that enhance the sensing response. The absorption spectra of UV–Visible spectroscopy showed an apparent change of increase in the absorbance and decrease in the optical band gap on addition of the dopant to the pure WO3 thin film. Filamentous structured porous thin films are discovered to have larger voids and greater surface roughness from FE-SEM and AFM, which aids in the adsorption of gas molecules. Mo-doped WO3 thin films showed a strong sensing response due to larger grain boundary scattering and wide pores abetting for more gas adsorption.

Picosecond Pulsed Laser Deposition of Metals and Metal Oxides.

In this work, we present the fabrication of thin films/nanostructures of metals and metal oxides using picosecond laser ablation. Two sets of experiments were performed: the depositions were carried out in vacuum and in air at atmospheric pressure. The subjects of investigation were the noble metals Au and Pt and the metal oxides ZnO and TiO2. We studied and compared the phase composition, microstructure, morphology, and physicochemical state of the as-deposited samples' surfaces in vacuum and in air. It was found that picosecond laser ablation performed in vacuum led to the fabrication of thin films with embedded and differently sized nanoparticles. The implementation of the same process in air at atmospheric pressure resulted in the fabrication of porous nanostructures composed of nanoparticles. The ablation of pure Pt metal in air led to the production of nanoparticles with an oxide shell. In addition, more defects were formed on the metal oxide surface when the samples were deposited in vacuum. Furthermore, the laser ablation process of pure Au metal in a picosecond regime in vacuum and in air was theoretically investigated using molecular dynamics simulation.