Search Results (184)

Reactive co-sputtering was applied to deposit TaN-(Ag,Cu) nanocomposite films on Si and tool steels. Prior to post-deposition annealing, the films were deposited with TaN cap (diffusion barrier) layers in various thicknesses in order to slow down the nucleation and growth of emerging Ag and Cu particles. The thickness of the cap layers was set at 5, 10, 20, or 50 nm. The films were then annealed using Rapid Thermal Annealing (RTA) at 400 °C to induce the nucleation and growth of Ag and Cu nanoparticles. These films’ surface morphologies and structures were examined. The samples were tested for their anti-wear and antibacterial behaviors against Gram-positive S. aureus and Gram-negative E. coli, with a variation in cap layer thickness. It is found that, through the application of TaN cap layers, the out-diffusion of Ag and Cu atoms may be slowed down. The surface concentrations of Ag and Cu might decrease from 35 at.% and 17 at.% to 18 at.% and 6 at.%, respectively, when the cap layer thickness increases to 50 nm (after being annealed for 12 min). The diffusion mechanism is proposed to explain the formation of nanoparticles on the surface through boundary diffusion. Antibacterial behaviors against both bacteria, as well as tribological properties, could still be effective but become less significant with an increase in the cap layer thickness. The antibacterial efficiency after 3 h testing decreased from 99% to 5% and 8% against E. coli and S. aureus, respectively. At 12 h, all the samples reached >99% antibacterial efficiency, despite the variation in cap thickness. For sliding wear, the wear rate was doubled when the cap thickness increased to 50 nm (when the normal load was 1 N). On the other hand, the difference was minor when the normal load was changed to 5 N. The sliding lifetime of the samples was studied using a tribometer. The total lifetime may increase with an increase in the cap thickness. The wear is found to be due to the oxidation of Ag and Cu nanoparticles, which results in the loss of low coefficient behaviors. Full article

We present a systematic study on the fabrication of gold nanoislands by microwave-assisted annealing, a rapid and energy-efficient alternative to conventional thermal treatments. Gold thin films with nominal thicknesses of 4, 5, 6, 8, and 10 nm are deposited by thermal evaporation directly onto BK7 glass substrates, with and without a 3 nm chromium adhesion layer. The samples are subsequently annealed in a microwave kiln, where microwave irradiation is absorbed and converted to heat within the graphite-coated cavity (kiln), allowing the substrate temperature to exceed 550 °C, the threshold required for film dewetting. This process induces a controlled morphological evolution from continuous thin films to well-defined nanoislands, with the final size distribution strongly dependent on the initial film thickness. Compared with oven-based annealing, microwave treatment promotes faster and more uniform heating, which enhances atomic diffusion and accelerates dewetting while reducing the risk of substrate deformation or excessive coalescence. The resulting nanoislands exhibit tailored size-dependent plasmonic properties, with clear correlations between film thickness, crystallite size, and optical absorption features. Importantly, the method is cost-efficient, requiring shorter processing times and lower energy input, while enabling reproducible fabrication of high-quality plasmonic nanostructures on inexpensive glass substrates, suitable for applications in sensing, photonics, and nanophotonics. Full article

Uncooled microbolometers play a pivotal role in infrared detection owing to their compactness, low power consumption, and cost-effectiveness. This review comprehensively summarizes recent progress in thermistor materials and focal plane arrays (FPAs), highlighting improvements in sensitivity and integration. Vanadium oxide (VO_x) remains predominant, with Al-doped films via atomic layer deposition (ALD) achieving a temperature coefficient of resistance (TCR) of −4.2%/K and significant 1/f noise reduction when combined with single-walled carbon nanotubes (SWCNTs). Silicon-based materials, such as phosphorus-doped hydrogenated amorphous silicon (α-Si:H), exhibit a TCR exceeding −5%/K, while titanium oxide (TiO_x) attains TCR values up to −7.2%/K through ALD and annealing. Emerging materials including GeSn alloys and semiconducting SWCNT networks show promise, with SWCNTs achieving a TCR of −6.5%/K and noise equivalent power (NEP) as low as 1.2 mW/√Hz. Advances in FPA technology feature pixel pitches reduced to 6 μm enabled by vertical nanotube thermal isolation, alongside the 3D heterogeneous integration of single-crystalline Si-based materials with readout circuits, yielding improved fill factors and responsivity. State-of-the-art VO_x-based FPAs demonstrate noise equivalent temperature differences (NETD) below 30 mK and specific detectivity (D*) near 2 × 10¹⁰ cm⋅Hz ^1/2/W. Future advancements will leverage materials-driven innovation (e.g., GeSn/SWCNT composites) and process optimization (e.g., plasma-enhanced ALD) to enable ultra-high-resolution imaging in both civil and military applications. This review underscores the central role of material innovation and system optimization in propelling microbolometer technology toward ultra-high resolution, high sensitivity, high reliability, and broad applicability. Full article

We investigated the protective properties of ultrathin laminated coatings, comprising three pairs of Al₂O₃ and TiO₂ sublayers with coating thicknesses < 150 nm, deposited on AISI 310 stainless steel (SS) and Si (100) substrates at 80–500 °C by atomic layer deposition. The coatings were chemically etched and subjected to corrosion, ultrasound, and thermal shock tests. The coating etching resistance efficiency (R_e) was determined by measuring via XRF the change in the coating sublayer mass thickness after etching in hot 80% H₂SO₄. The maximum R_e values of ≥98% for both alumina and titania sublayers were obtained for the laminates deposited at 250–400 °C on both substrates. In these coatings, the titania sublayers were crystalline. The lowest R_e values of 15% and 50% for the alumina and titania sublayers, respectively, were measured for laminate grown at 80 °C on silicon. The coatings deposited at 160–200 °C demonstrated a delay in the increase of R_e values, attributed to the changes in the titania sublayers before full crystallization. Coatings grown at higher temperatures were also more resistant to ultrasound and liquid nitrogen treatments. In contrast, coatings deposited at 125 °C on SS had better corrosion protection, as demonstrated via electrochemical impedance spectroscopy and a standard immersion test in FeCl₃ solution. Full article

In this study, Hf_0.5Zr_0.5O₂ (HZO) thin-films were deposited using a Co-plasma atomic layer deposition (CPALD) process that combined both remote plasma and direct plasma, for the development of ferroelectric memory devices. Ferroelectric capacitors with a symmetric hybrid TiN/W/HZO/W/TiN electrode structure, incorporating W electrodes as insertion layers, were fabricated. Rapid thermal annealing (RTA) was subsequently employed to control the crystalline phase of the films. The electrical and structural properties of the capacitors were analyzed based on the RTA temperature, and the presence, thickness, and position of the W insertion electrode layer. Consequently, the capacitor with 5 nm-thick W electrode layers inserted on both the top and bottom sides and annealed at 700 °C exhibited the highest remnant polarization (2P_r = 61.0 μC/cm²). Moreover, the symmetric hybrid electrode capacitors annealed at 500–600 °C also exhibited high 2P_r values of approximately 50.4 μC/cm², with a leakage current density of approximately 4 × 10⁻⁵ A/cm² under an electric field of 2.5 MV/cm. The findings of this study are expected to contribute to the development of electrode structures for improved performance of HZO-based ferroelectric memory devices. Full article

Aluminum nitride (AlN) thin films were deposited on SiO₂ substrates by RF-magnetron sputtering at varying powers (110–140 W) and subsequently subjected to thermal annealing at 450 °C under nitrogen atmosphere. A comprehensive multi-technique investigation—including X-ray reflectometry (XRR), X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), optical profilometry, spectroscopic ellipsometry (SE), and electrical measurements—was performed to explore the physical structure, morphology, and optical and electrical properties of the films. The analysis of the film structure by XRR revealed that increasing sputtering power resulted in thicker, denser AlN layers, while thermal treatment promoted densification by reducing density gradients but also induced surface roughening and the formation of island-like morphologies. Optical studies confirmed excellent transparency (>80% transmittance in the near-infrared region) and demonstrated the tunability of the refractive index with sputtering power, critical for optoelectronic applications. The electrical characterization of Au/AlN/Al sandwich structures revealed a transition from Ohmic to trap-controlled space charge limited current (SCLC) behavior under forward bias—a transport mechanism frequently present in a material with very low mobility, such as AlN—while Schottky conduction dominated under reverse bias. The systematic correlation between deposition parameters, thermal treatment, and the resulting physical properties offers valuable pathways to engineer AlN thin films for next-generation optoelectronic and high-frequency device applications. Full article

Polyamide 6,6 (PA6,6) fabrics are widely used in textiles due to their high mechanical strength and chemical stability. However, their inherent flammability and melting behavior under fire pose significant safety challenges. In this study, a dual-layer flame-retardant system was developed by integrating atomic layer deposition (ALD) of ZnO with a phosphorus–silane-based flame retardant (DOPO-ETES). ALD allowed precise control of ZnO layer thickness (50, 84, and 199 nm), ensuring uniform coating. Thermal analysis (TGA) and microscale combustion calorimetry (MCC) revealed that ZnO altered the degradation pathway of PA6,6 through catalytic effects, promoting char formation and reducing heat release. The combination of ZnO and DOPO-ETES resulted in further reductions in heat release rates. However, direct flame tests showed that self-extinguishing behavior was not achieved, emphasizing the limitations related to the melting of PA6,6. TG-IR and cone calorimetry confirmed that ZnO coatings suppressed the release of smoke-related volatiles and incomplete combustion products. These findings highlight the potential of combining metal-based catalytic flame retardants like ZnO with phosphorus-based coatings to improve flame retardancy while addressing the specific challenges of polyamide textiles. This approach may also be adapted to other fabric types and integrated with additional flame retardants, broadening its relevance for textile applications. Full article

In this research work, two distinct types of three-dimensional (3D) capacitors were successfully fabricated, each with its own unique features and advantages. The first type of capacitor is centered around a 3D nanoporous structure. This structure is formed on a nickel substrate through anodic oxidation. After undergoing high-temperature thermal oxidation, a monolithic Ni-NiO-Pt metal–insulator–metal (MIM) capacitor with a nanoporous dielectric architecture is achieved. Structurally, this innovative design brings about several remarkable benefits. Due to the nanoporous structure, it has a significantly increased surface area, which can effectively store more charges. As a result, it exhibits an equivalent capacitance density of 69.95 nF/cm², which is approximately 18 times higher than that of its planar, non-porous counterpart. This high capacitance density enables it to store more electrical energy in a given volume, making it highly suitable for applications where miniaturization and high energy storage in a small space is crucial. The second type of capacitor makes use of Through-Glass Via (TGV) technology. This technology is employed to create an interdigitated blind-via array within a glass substrate, attaining an impressively high aspect ratio of 22.5:1 (with a via diameter of 20 μm and a depth of 450 μm). By integrating atomic layer deposition (ALD), a conformal interdigital electrode structure is realized. Glass, as a key material in this capacitor, has outstanding insulating properties. This characteristic endows the capacitor with a high breakdown field strength exceeding 8.2 MV/cm, corresponding to a withstand voltage of 5000 V. High breakdown field strength and withstand voltage mean that the capacitor can handle high-voltage applications without breaking down easily, which is essential for power-intensive systems like high-voltage power supplies and some high-power pulse-generating equipment. Moreover, due to the low-loss property of glass, the capacitor can achieve an energy conversion efficiency of up to 95%. Such a high energy conversion efficiency ensures that less energy is wasted during the charge–discharge process, which is highly beneficial for energy-saving applications and systems that require high-efficiency energy utilization. Full article

The gate reliability issues in SiC-based devices with a gate dielectric formed through heat oxidation are important factors limiting their application in power devices. Aluminum oxide (Al₂O₃) and titanium dioxide (TiO₂) were combined using the ALD process to form a composite AlTiO gate dielectric on a 4H-SiC substrate. TDMAT and TMA were the precursors selected and deposited at 200 °C, and the samples were Ar or N₂ annealed at temperatures ranging from 300 °C to 700 °C. An XPS analysis suggested that the AlTiO film had been deposited with a high overall quality and the involvement of Ti atoms had increased the interfacial bonding with the substrate. The as-deposited MOS structure had band shifts of ΔE_C = 1.08 eV and ΔE_V = 2.41 eV. After annealing, the AlTiO bandgap increased by 0.85 eV at most, and better band alignment was attained. Leakage current and breakdown voltage characteristic investigations were conducted after Al electrode deposition. The leakage current density and electrical breakdown field of an MOS capacitor structure with a SiC substrate were ~10⁻³ A/cm² and 6.3 MV/cm, respectively. After the annealing process, both the measures of the JV performance of the MOS capacitor had improved to ~10⁻⁶ A/cm² and 7.2 MV/cm. The interface charge N_eff of the AlTiO layer was 4.019 × 10¹⁰ cm⁻². The AlTiO/SiC structure fabricated in this work proved the feasibility of adjusting the properties of single-component gate dielectric materials using the ALD method, and using a suitable thermal annealing process has great potential to improve the performance of the compound MOS dielectric layer. Full article

Dynamic random-access memory (DRAM) is a vital component in modern computing systems. Enhancing memory performance requires maximizing capacitor capacitance within DRAM cells, which is achieved using high-k dielectric materials deposited as thin, uniform films via atomic layer deposition (ALD). Precise film deposition that minimizes electronic defects caused by charged vacancies is essential for reducing leakage current and ensuring high dielectric strength. In this study, we fabricated metal–insulator–metal (MIM) capacitors in high-aspect-ratio trench structures using remote plasma ALD (RP-ALD) and direct plasma ALD (DP-ALD). The trenches, etched into silicon, featured a 7:1 aspect ratio, 76 nm pitch, and 38 nm critical dimension. We evaluated the electrical characteristics of HfO₂-based capacitors with TiN top and bottom electrodes, focusing on leakage current density and equivalent oxide thickness. Capacitance–voltage analysis and X-ray photoelectron spectroscopy (XPS) revealed that RP-ALD effectively suppressed plasma-induced damage, reducing defect density and leakage current. While DP-ALD offered excellent film properties, it suffered from degraded lateral uniformity due to direct plasma exposure. Given its superior lateral uniformity, lower leakage, and defect suppression, RP-ALD shows strong potential for improving DRAM capacitor performance and serves as a promising alternative to the currently adopted thermal ALD process. Full article

Silica aerogels exhibit exceptionally low thermal conductivity and a low apparent density, as they are unique porous nanomaterials. They are extensively used in thermal insulation in terms of aerospace and building construction, adsorption processes for environmental applications, concentrating solar power systems, and so on. However, the degradation of the silica aerogel’s nanoporous structure at high temperatures seriously restricts their practical applications. Through a comprehensive review of the high-temperature structural evolution and sintering mechanisms of silica aerogels, this paper introduces two strategies to enhance their thermal stability, including heteroatom doping and surface heterogeneous structure construction. In particular, atomic layer deposition (ALD) of ultra-thin coatings on silica aerogel holds significant potential for enhancing thermal stability, while preserving its ultra-low thermal conductivity. Full article

Single-junction perovskite solar cells (PSCs) have been one of the most promising photovoltaic technologies owing to their high-power conversion efficiencies (PCEs) of ~27% and the low-cost fabrication processes involved, which pay off significantly given their distinct structural characteristics. Recently, inorganic hole-transport materials (HTMs) such as nickel oxide (NiO_x) have been developed and received considerable attention for use in OPVs due to their excellent thermal stability, low-cost materials, and compatibility with scalable deposition methods. Here, we summarize the recent progress on inorganic HTMs for PSCs, which can be divided into three categories: NiO_x, copper-based compounds, and emerging new alternatives. The deposition method (sputtering, atomic layer deposition, or a solution-based technique) is one of the most important factors affecting the performance and stability of PSCs. Finally, we review interfacial engineering strategies, such as surface modifications and doping, which can enhance charge transport and extend a device’s lifetime. We also balance the benefits of inorganic HTMs against the key challenges in advancing to commercialization, namely interior defects and environmental degradation. In this review, we summarize the recent progress and challenges toward developing cost-efficient and stable PSCs with inorganic HTMs and provide insights into the future development of these materials. Full article

Extreme ultraviolet (EUV) imagers are key tools to monitor the space environment and forecast space weather. EUV filters are important components to block radiation in the ultraviolet (UV), visible, and near-infrared (IR) regions. In this study, various characterization methods were proposed for the nickel mesh-supported indium (In) filter, and their spectral characteristics were comprehensively studied. The material and thickness of the filter were chosen based on atomic scattering principles, determined through theoretical calculation and software simulation. The metal film was deposited using the vacuum-resistive thermal evaporation method. The measured transmission of the filter was 10.06% at 83.4 nm. The surface elements of the sample were analyzed using X-ray photoelectron spectroscopy (XPS). The surface and cross-sectional morphologies of the filter were observed using a scanning electron microscope (SEM). The impact of the oxide layer and carbon contamination on the filter’s transmittance was investigated using an ellipsometer. A multilayer “In-In₂O₃-C” model was established to determine the thickness of both the oxide layer and carbon contamination layer on the filter. This model introduces the filling factor based on the original model and considers the diffusion of the contamination layer, resulting in more accurate fitting results. The transmittance of the filter in the visible light range was measured using a UV-VIS spectrophotometer, and the measurement error was analyzed. This article provides preparation methods and test methods for the 83.4 nm EUV filter and conducts a detailed analysis of the spectral characteristics of the prepared optical filters, which hold significant value for space exploration applications. Full article

Vanadium and oxygen form a complex system of vanadium oxides with multiple phases and mixed valency, increasing the difficulty of characterization. In this work, amorphous vanadium oxide thin films with mixed valence states were fabricated by atomic layer deposition, and then post-annealing was conducted for crystalline films. For the surface analysis of this mixed-valence system, X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) were employed. However, XPS is only able to quasi-quantitatively determine the surface-proximity oxidation states. To account for the inadequacy of surface-sensitive XPS and AES techniques, a surface oxidation model (SOM) was proposed for the ellipsometric modeling of the mixed-valence system. Furthermore, by conducting air thermal oxidation (ATO) experiments, the four sets of fitting parameters of SOM were decreased to three, lowering the system complexity. This study is expected to help with the analysis of vanadium oxide mixed-valence systems and other multivalent metal oxide systems. Full article

This study investigates the enhancement of thermal conductivity in silicon carbide (SiC) matrix pellets for accident-tolerant fuels via atomic layer deposition (ALD) of alumina (Al₂O₃) coatings. Pressure-holding ALD protocols ensured precursor saturation, enabling precise coating control (0.09 nm/cycle). The ALD-coated Al₂O₃ layers on SiC particles were found to be more uniform while minimizing surface oxidation compared to traditional mechanical mixing. Combined with yttria (Y₂O₃) additives and spark plasma sintering (SPS), ALD-coated samples achieved satisfactory densification and thermal performance. Results demonstrated that 5~7 wt.% ALD-Al₂O₃ + Y₂O₃ achieved corrected thermal conductivity enhancements of 14~18% at 100 °C., even with reduced sintering aid content, while maintaining sintered densities above 92% T.D. (theoretical density). This work highlights ALD’s potential in fabricating high-performance, accident-tolerant SiC-based fuels for safer and more efficient nuclear reactors, with implications for future optimization of sintering processes and additive formulations. Full article