Search Results (131)

Diamond, as an exceptional material with many superior properties, requires a single crystal in a reasonably large size for practical industrial applications. However, achieving large-area single-crystal diamond (SCD) growth without the formation of polycrystalline rims remains challenging. Microwave plasma chemical vapor deposition (MPCVD) using a gas mixture of 10% CH₄-H₂ was used for the homoepitaxial growth of (001) SCD. The effect of nitrogen gas addition in the range of 0–2000 ppm on lateral growth was investigated. Deposition with 180 ppm N₂ over a growth duration of 20 h to reach a thickness of 0.95 mm resulted in significantly enhanced lateral growth without the appearance of a polycrystalline diamond (PCD) rim for the grown diamond, and the total top surface area of SCD increased by an area gain of 1.6 relative to the substrate. The corresponding vertical and lateral growth rates were 47.3 µm/h and 52.5 µm/h, respectively. Characterization by Raman spectroscopy and atomic force microscopy (AFM) revealed uniform structural integrity across the whole surface from the laterally grown regions to the center, including the entire expanded area, in terms of surface morphology and crystalline quality. Moreover, measurements of the etch pit densities (EPDs) showed a substantial reduction in the laterally grown regions, approximately an order of magnitude lower than those in the central region. The high quality of the homoepitaxial diamond layer was further verified with (004) X-ray rocking curve analysis, showing a narrow full width at half maximum (FWHM) of 11 arcsec. Full article

In this study, we investigate the improvement of physical and electrical characteristics in 4H-silicon carbide (SiC) MOS capacitors using Aluminum Oxynitride (AlON) thin films fabricated via Plasma-Enhanced Atomic Layer Deposition (PEALD). AlON thin films are grown on SiC substrates using a high ratio of NH₃ and O₂ as nitrogen and oxygen sources through PEALD technology, with improved material properties and electrical performance. The AlON films exhibited excellent thickness uniformity, with a minimal error of only 0.14%, a high refractive index of 1.90, and a low surface roughness of 0.912 nm, demonstrating the precision of the PEALD process. Through XPS depth profiling and electrical characterization, it was found that the AlON/SiC interface showed a smooth transition from Al-N and Al-O at the surface to Al-O-Si at the interface, ensuring robust bonding. Electrical measurements indicated that the SiC/AlON MOS capacitors demonstrated Type I band alignment with a valence band offset of 1.68 eV and a conduction band offset of 1.16 eV. Additionally, the device demonstrated a low interface state density (D_it) of 7.6 × 10¹¹ cm⁻²·eV⁻¹ with a high breakdown field strength of 10.4 MV/cm. The results highlight AlON’s potential for enhancing the performance of high-voltage, high-power SiC devices. Full article

MgF₂ films are prepared using plasma-enhanced atomic layer deposition (PEALD). The influence of substrate temperature on the growth behavior, chemical composition, and optical properties of MgF₂ films is systematically investigated. The experimental results show that the deposition process transitions through three distinct regimes: an incomplete-reaction regime at 100 °C, a self-limiting ALD window at 125–150 °C, and a chemical vapor deposition (CVD)-like regime above 175 °C. At 100 °C, incomplete surface chemistry yields low growth-per-cycle, carbon incorporation, and an elevated refractive index. Within 125–150 °C, films are near-stoichiometric, smooth, and exhibit a low refractive index ≈ 1.37 ± 0.003 at 550 nm. Above 175 °C, precursor decomposition drives non-self-limiting growth with increased roughness. As an application-level validation, a film grown at 125 °C used as a double-sided antireflection coating on glass increases transmittance from 92 ± 0.1% (bare) to 97.2% ± 0.2% at 550 nm. The average transmittance of 96.4 ± 0.2% over 380–780 nm can be achieved. Overall, this work establishes the relationship between deposition temperature and PEALD-MgF₂ film properties and demonstrates precise, low-temperature, non-corrosive deposition suitable for advanced optical antireflection coatings. Full article

Graphene was directly grown on SiO₂/Si substrates using microwave plasma-enhanced chemical vapor deposition (PECVD) to investigate how synthesis-driven variations in structure and doping influence carrier transport. The effects of synthesis temperature, plasma power, deposition time, gas flow, and pressure on graphene’s structure and electronic properties were systematically studied. Raman spectroscopy revealed non-monotonic changes in layer number, defect density, and doping levels, reflecting the complex interplay between growth, etching, and self-doping mechanisms. The surface morphology and conductivity were assessed by atomic force microscopy (AFM). Charge carrier mobility, extracted from graphene-based field-effect transistors, showed strong correlations with Raman features, including the intensity ratios and positions of the Two-dimension (2D) and G peaks. Importantly, mobility did not correlate with defect density but was linked to reduced self-doping and a weaker graphene–substrate interaction rather than intrinsic structural disorder. These findings suggest that charge transport in PECVD-grown graphene is predominantly limited by interfacial and doping effects. This study offers valuable insights into the synthesis–structure–property relationship, which is crucial for optimizing graphene for electronic and sensing applications. 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

High-density polyethylene (HDPE) is widely used for different applications, but its low resistance to ultraviolet radiation, plastic deformation, chemical stability, and wear re-sistance limits its use in high-demand work environments. Modifying of the surface characteristics could improve the work efficiency of the parts exposed to an aggressive environment. Plasma treatments change the surface characteristics with deposition of a coating or by modifying the surface’s energy, varying the surface properties. This study presents the mechanical and tribological properties of a titanium (Ti) layer with fiber-like morphology produced on HDPE surfaces by plasma treatment involving plasma etching and the deposition of Ti atoms, through DC magnetron sputtering. On the HDPE substrates grew up Ti layer with fibers-like morphology with a diameter of 1.6 ± 0.44 μm. These fibers were elemental composed by 91.5 ± 0.9% Ti and 8.5 ± 0.6% O with α-Ti phase combined with HDPE crystalline structure. The Ti coating increased the hardness of the substrate and showed a good adhesion to HDPE surface. During the sliding test, the Ti layer with fiber-like morphology exhibited plastic deformation and debris accumulation, leading to the formation of a tribolayer without layer detachment. Notably, no detachment of the layer was observed, effectively protected the polymer surface, and enhanced its performance for tribological applications. Full article

To mitigate the high residual stress inherent in single-layer diamond-like carbon (DLC) films, we fabricate alternating soft/hard multilayer DLC thick films using a cage-type hollow cathode plasma-enhanced chemical vapor deposition (PECVD) system. The microstructure, mechanical properties, and corrosion resistance of these films were systematically investigated. Periodic film structures were characterized via scanning electron microscopy (SEM), Raman spectroscopy, atomic force microscopy (AFM), and X-Ray photoelectron spectroscopy (XPS). Adhesion and hardness were evaluated using a scratch tester and a nanoindentation tester, respectively, while corrosion resistance was assessed by dynamic potential polarization tests in a 3.5 wt% NaCl solution. Findings indicate that as the modulation period of the Si-DLC films increases, a greater proportion of high-energy carbon particles penetrate the non-biased layer under workpiece bias, ultimately disrupting the layered structure in the 90-layer film. This results in densification, reflected in three key improvements: (1) an increase in sp³-bonded carbon content and enhanced smoothness, (2) enhanced adhesion (from 34 N to 46 N) and nanohardness (from 4.94 GPa to 8.41 GPa), and (3) a tenfold reduction in corrosion current density (i_corr) compared to single-layer Si-DLC films. Full article

The GaN-based green miniaturized light-emitting diode (mini-LED) is a key component for the realization of full-color display. Optimized passivation layers can alleviate the trapping of carriers by sidewall defects and are regarded as an effective way to improve the external quantum efficiency (EQE) efficiency of mini-LEDs. Since AlN has a closer lattice match to GaN compared to other heterogeneous passivation materials, we boosted the EQE of GaN-based green flip-chip mini-LEDs through the deposition of a lattice-compatible AlN passivation layer through atomic layer deposition (ALD) and a SiO₂ passivation layer through plasma-enhanced chemical vapor deposition (PECVD). Benefiting from reduced sidewall nonradiative recombination, the EQE of the green flip-chip mini-LED with a composite ALD-AlN/PECVD-SiO₂ passivation layer reached 34.14% at 5 mA, which is 34.6% higher than that of the green flip-chip mini-LED with a single PECVD-SiO₂ passivation layer. The results provide guidance for the realization of high-performance mini-LEDs by selecting lattice-compatible passivation layers. Full article

The tin dioxide (SnO₂) thin films in this work were prepared by using plasma-enhanced atomic layer deposition (PEALD), and a systematic analysis was conducted to evaluate the influence of post-deposition annealing at various temperatures in a nitrogen–hydrogen mixed atmosphere on their surface morphology, optical behavior, and electrical performance. The SnO₂ films were characterized by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Hall effect measurements. With increasing annealing temperatures, the SnO₂ films exhibited enhanced crystallinity, a higher oxygen vacancy (O_V) peak area ratio, and improved mobility and carrier concentration. These enhancements make the annealed SnO₂ films highly suitable as electron transport layers (ETLs) in perovskite solar cells (PSCs), providing practical guidance for the design of high-performance PSCs. 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

The advancement of portable high-definition organic light-emitting diode (OLED) displays necessitates thin film transistors (TFTs) with low power consumption and high pixel density. Amorphous indium gallium zinc oxide (a-IGZO) TFTs are promising candidates to meet these requirements. However, conventional silicon dioxide gate insulators provide limited channel modulation due to their low dielectric constant, while alternative high-k dielectrics often suffer from high leakage currents and poor surface quality. Plasma-enhanced atomic layer deposition (PEALD) enables the atomic-level control of film thickness, resulting in high-quality films with superior conformality and uniformity. In this work, a systematic investigation was conducted on the properties of HfO₂ films and the electrical characteristics of a-IGZO TFTs with different HfO₂ thicknesses. A Vth of −0.9 V, μ_sat of 6.76 cm²/Vs, SS of 0.084 V/decade, and I_on/I_off of 1.35 × 10⁹ are obtained for IGZO TFTs with 40 nm HfO₂. It is believed that the IGZO TFTs based on a HfO₂ gate insulating layer and prepared by PEALD can improve electrical performance. Full article

The lack of ultra-thin, controllable dielectric layers poses challenges for reducing power consumption in 2D FETs. In this study, plasma-enhanced atomic layer deposition was employed to fabricate a highly reliable, ultra-thin aluminum oxide (Al₂O₃) dielectric layer with a thickness of 4 nm. The Al₂O₃ film grown on highly conductive silicon substrates demonstrated a maximum breakdown field of 5.98 MV/cm and a leakage current density as low as 2.48 × 10⁻⁷ A/cm² at 1 MV/cm. MoS₂ FETs incorporating this Al₂O₃ gate dielectric exhibited high-performance n-type characteristics at a low operating voltage of 1 V, achieving a subthreshold swing (SS) of 65 mV/dec, a threshold voltage (V_th) of −0.96 V, a high carrier mobility (μ) of 34.85 cm²·V⁻¹·s⁻¹, and an on/off current ratio exceeding 10⁶. These results highlight the potential of Al₂O₃ in enabling low-power 2D electronic devices for post-Moore applications. 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

In this work, micro Zn-doped Ga₂O₃ films (GZO) were deposited by one-step mixed atomic layer deposition (ALD) followed by post-thermal engineering. The effects of Zn doping and post-annealing temperature on both structure characteristics and electric properties were investigated in detail. The combination of plasma-enhanced ALD of Ga₂O₃ and thermal ALD of ZnO can realize the fast growth rate (0.62 nm/supercyc.), high density (4.9 g/cm³), and smooth interface (average R_q = 0.51 nm) of Zn-doped Ga₂O₃ film. In addition, the thermal engineering of the GZO was achieved by setting the annealing temperature to 400, 600, 800, and 1000 °C, respectively. The GZO film annealed at 800 °C exhibits a typical crystalline structure (Ga₂O₃: β phase, ZnO: hexagonal wurtzite), a lower roughness (average R_q = 2.7 nm), and a higher average breakdown field (16.47 MV/cm). Notably, compared with the pure GZO film, the breakdown field annealed at 800 °C increases by 180%. The O_V content in the GZO after annealing at 800 °C is as low as 34.8%, resulting in a remarkable enhancement of electrical properties. These research findings offer a new perspective on the high-quality ALD-doped materials and application of GZO in high-power electronics and high-sensitive devices. Full article

This study provides a systematic review of photocatalytic fiber coating technology as a potential solution to challenges in the textile industry. An analysis of recent research (2020–2024) reveals significant developments in materials and methods. Traditional photocatalysts (TiO₂ and ZnO) are being enhanced through doping and nanostructure control, and novel materials such as graphene-based composites and metal-organic frameworks are emerging. Advanced coating technologies, such as plasma treatment, atomic layer deposition, and magnetron sputtering, have been introduced to improve coating uniformity and durability. Key trends include the development of multifunctional coatings that combine self-cleaning, antibacterial effects, ultraviolet (UV) protection, and superhydrophobic properties. Environmental sustainability is advancing through eco-friendly manufacturing processes, although concerns regarding nanoparticle safety persist. While applications are expanding into medical textiles, protective gear, and wastewater treatment, challenges remain in terms of mass production technology, cost-effectiveness, and long-term durability. Future research should focus on nanostructure control, the development of visible-light-active materials, the optimization of coating processes, and the investigation of environmental impacts. This review suggests that photocatalytic fiber coating technology can significantly contribute to sustainable textile industry development when these challenges are effectively addressed. Full article