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Excellent corrosion resistance of graphene coating on copper due to the low defect overlapping structure
摘要： Nowadays, ultra-thin graphene coating can provide considerable resistance against corrosion for various metals, however, there is great variability and contradictory in corrosion resistance mechanism of graphene coating reported in different studies. In this work, the anti-corrosion behaviors of graphene coatings with different defect values on the copper surface were investigated systematically. The results indicated that all graphene coated Cu exhibited superior corrosion resistance than heat treated Cu, regardless of the layer number of graphene. Particularly, anti-corrosion performance of bi-layer graphene coating was the most effective, the corrosive medium transferred a long way to reach the interface between Cu and graphene. The corrosion resistance for mono-layer graphene was inferior to bi-layer graphene, and poor corrosion resistance for multi-layer graphene was due to the high value of defects increasing the corrosion pathways, which leads to easier transfer for the chloride ions among defects. Consequently, the corrosion resistance ability of graphene coatings was mainly determined by the defect density other than the layer number, multi-layer graphene coating may not behave better anti-corrosion performance if it contained a high value of defect.
关键词： graphene,galvanic corrosion,layer number,SVET,CVD,defect
更新于2025-11-21 11:08:12
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Hydrogen Induced Etching Features of Wrinkled Graphene Domains
摘要： Wrinkles are observed commonly in CVD (chemical vapor deposition)-grown graphene on Cu and hydrogen etching is of significant interest to understand the growth details, as well as a practical tool for fabricating functional graphene nanostructures. Here, we demonstrate a special hydrogen etching phenomenon of wrinkled graphene domains. We investigated the wrinkling of graphene domains under fast cooling conditions and the results indicated that wrinkles in the monolayer area formed more easily compared to the multilayer area (≥two layers), and the boundary of the multilayer area tended to be a high density wrinkle zone in those graphene domains, with a small portion of multilayer area in the center. Due to the site-selective adsorption of atomic hydrogen on wrinkled regions, the boundary of the multilayer area became a new initial point for the etching process, aside from the domain edge and random defect sites, as reported before, leading to the separation of the monolayer and multilayer area over time. A schematic model was drawn to illustrate how the etching of wrinkled graphene was generated and propagated. This work may provide valuable guidance for the design and growth of nanostructures based on wrinkled graphene.
关键词： graphene,hydrogen etching,wrinkling,CVD synthesis
更新于2025-11-21 11:01:37
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A spark discharge generator for scalable aerosol CVD synthesis of single-walled carbon nanotubes with tailored characteristics
摘要： We have designed and built an exhaust-free spark discharge generator for robust aerosol CVD synthesis of single-walled carbon nanotubes. The systematic study has shown the generator to provide a facile and repeatable route to precisely control the size of the catalyst particle and, therefore, carbon nanotube growth. Using a comprehensive set of methods (the analysis of differential mobility of the aerosol particles, optical spectroscopy, scanning and transmission electron microscopy, Raman spectroscopy, and atomic force microscopy) we have revealed the relation between the defectiveness, length, diameter distribution of carbon nanotubes and specific features of a generator such as electrode characteristics (breakdown voltage, composition, and current) as well as the nature of the surrounding media (carrier gas nature, flow rate). The design used has resulted in separation of the nanoparticle formation and carbon nanotube nucleation processes. This provides a mutual independence of the growth parameters and the diameter distribution of the single-walled carbon nanotubes enhancing the scalability of the process. For instance, the breakdown voltage has been shown to have nearly zero effect on diameter and length distribution of carbon nanotubes produced while strictly governing the yield. We focus here on producing specifically short carbon nanotubes (l < 500nm) of pronounced defectiveness for drug delivery and transistor applications.
关键词： single-walled carbon nanotubes,differential mobility analyzer,catalyst activation,spark-discharge generator,aerosol CVD,floating bed reactor
更新于2025-11-14 17:03:37
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Low-Temperature Graphene Growth by Forced Convection of Plasma-Excited Radicals
摘要： We developed the forced convection (FC)-PECVD method for the synthesis of graphene in which a specially designed blowing plasma source is used at moderate gas pressure (1-10 Torr) and the distribution of reactive radicals reaching the substrate surface can be controlled by forced convection. Self-limiting growth of graphene occurs on copper foil and monolayer graphene growth with few defects is achieved even at low temperature (<400 °C). We also demonstrated the enlargement of growth area using the scalable blowing plasma source. We expect that the FC-PECVD method overcomes the limitations of conventional low-temperature PECVD and provides a breakthrough for the achievement of industrial applications based on graphene.
关键词： low temperature growth,self-limiting growth,Graphene,forced-convection plasma CVD
更新于2025-09-23 15:23:52
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A novel SiC nanowire aerogel consisted of ultra long SiC nanowires
摘要： SiC nanowire aerogel (SNA) with highly porous 3D nanowire architecture was synthesized by polymer pyrolysis chemical vapor deposition (PPCVD) process to deposit SiC nanowires in the pores of carbon foam, followed by high temperature oxidation of carbon foam. The microstructure of the prepared SNA was characterized by SEM, TEM and a large number of interweaving SiC nanowires with a diameter of 80-100 nm and a length of hundreds of micrometers form the highly porous 3D nanowire architecture of SNA. The prepared SNA possesses the performance combination of ultra-low density (30±7 mg·cm-3), high-temperature oxidation resistance (750 °C), noncombustible and fire resistance property in the fire, excellent thermal insulating property (0.03 W·m-1·k-1 at room temperature in He) and compressive strength of 0.11 MPa, which is applicable as high-temperature heat insulator, ceramic matrix composite, high temperature flue gas filter, fire-proofing material and catalyst carrier.
关键词： Carbon foam,Aerogel,SiC nanowire,CVD
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE International Meeting for Future of Electron Devices, Kansai (IMFEDK) - Kyoto, Japan (2018.6.21-2018.6.22)] 2018 IEEE International Meeting for Future of Electron Devices, Kansai (IMFEDK) - Thermoelectric Conversion Devise Using Ga-Sn-O Thin Film Prepared by Mist CVD Method
摘要： We proposed a GTO thin film thermoelectric conversion devise by the mist CVD method. The thermoelectric conversion devise with the best performance had a Seebeck coefficient of -193[μV/K], a conductivity of 6.35[S/cm], and a PF of 0.0179[mW/mK2].
关键词： Ga-Sn-O,Seebeck coefficient,conductivity,mist CVD,power factor
更新于2025-09-23 15:23:52
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ZnO-based nanocomposites prepared by a vapor phase route, investigated by XPS
摘要： Nanostructured materials based on ZnO, eventually functionalized with titanium oxide (TiO2) or tungsten oxide (WO3), were fabricated on fluorine-doped tin oxide-coated glass substrates by a combined chemical vapor deposition/radio frequency-sputtering route. In particular, the present work focuses on the use of x-ray photoelectron and x-ray excited Auger electron spectroscopies for a detailed investigation of the system O 1s, Zn 2p3/2, Zn 3p, and Zn LMM core levels, as well as Ti 2p and W 4f photoelectron peaks. In a nutshell, the results of these analyses highlight the obtainment of pure ZnO nanodeposits, as well as of ZnO-TiO2 and ZnO-WO3 composites, in which the identity of each component is preserved, and the occurrence of an electronic interplay between ZnO and WO3 phases in the latter system.
关键词： RF-sputtering,CVD,x-ray photoelectron spectroscopy,WO3,TiO2,ZnO
更新于2025-09-23 15:22:29
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Selective Area Deposition of Hot Filament CVD Diamond on 100 mm MOCVD Grown AlGaN/GaN Wafers
摘要： A new technique is reported for selective growth of polycrystalline diamond by hot filament chemical vapor deposition (HFCVD) on AlGaN/GaN-on-Si (111) wafers without degradation of the underlying layers. Selective diamond seeding is accomplished by dispersing nano-diamond seeds in photoresist and patterned lithographically prior to HFCVD growth. A thin layer of plasma enhanced CVD SiNx, deposited prior to seeding and diamond deposition, was found to be essential to protect the AlGaN/GaN wafer. Methane concentration of 3.0% was used to achieve increased diamond growth rate and faster surface coverage. Excellent selectivity and minimal AlGaN surface damage were achieved due to the protective layer and faster surface coverage with increased methane concentration. Damage mitigation was confirmed by comparison of atomic force microscopy, x-ray diffraction, and Raman spectroscopy, each conducted before and after diamond deposition, and by SEM images of the final structures.
关键词： 2DEG,Reciprocal space mapping,III-Nitride,SiNx,Selective area deposition,CVD diamond,Photolithography,GaN decomposition
更新于2025-09-23 15:22:29
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Effects of substrate temperature and precursor amount on optical properties and microstructure of CVD deposited amorphous TiO2 thin films
摘要： In this research, TiO2 thin films were deposited on glass substrate by chemical vapor deposition using tetra isopropylorthotitanate as a precursor at low temperature. The TiO2 thin films were formed without using an oxygen source or annealing. Effects of substrate temperature and amount of the precursor on surface microstructure and optical properties of deposited TiO2 thin films were investigated. X-ray diffraction (XRD), UV-visible spectrophotometry and atomic force microscopy (AFM) were used to analyze the fabricated layers. The XRD analysis revealed that structure of all prepared layers was in amorphous phase. Analysis of AFM images showed that by increasing substrate temperature, the layer surfaces became rougher and simultaneously nanoparticle size was more uniform. Texture analysis revealed that increasing substrate temperature and decreasing precursor amount both increased surface isotropy. Thickness of layers was calculated by applying the Swanepoel method to the transmittance spectra. Variations in optical parameters were studied, including of optical band gap, refractive index, extinction coefficient, complex dielectric function, Urbach energy, single oscillator energy and dispersion energy. The results indicated that optical properties were functions of substrate temperature and precursor amount.
关键词： CVD,TiO2 thin film,Substrate temperature,Optical properties,Amorphous structure
更新于2025-09-23 15:22:29
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A Peeling Approach for Integrated Manufacturing of Large Mono-Layer h-BN Crystals
摘要： Hexagonal boron nitride (h-BN) is the only known material aside from graphite with a structure composed of simple, stable, non-corrugated atomically thin layers. While historically used as lubricant in powder form, h-BN layers have become particularly attractive as an ultimately thin insulator, barrier or encapsulant. Practically all emerging electronic and photonic device concepts currently rely on h-BN exfoliated from small bulk crystallites, which limits device dimensions and process scalability. We here focus on a systematic understanding of Pt catalysed h-BN crystal formation, in order to address this integration challenge for mono-layer h-BN via an integrated chemical vapour deposition (CVD) process that enables h-BN crystal domain sizes exceeding 0.5 mm and a merged, continuous layer in a growth time less than 45 min. The process makes use of commercial, reusable Pt foils, and allows a delamination process for easy and clean h-BN layer transfer. We demonstrate sequential pick-up for the assembly of graphene/h-BN heterostructures with atomic layer precision, while minimizing interfacial contamination. The approach can be readily combined with other layered materials and enables the integration of CVD h-BN into high quality, reliable 2D material device layer stacks.
关键词： transfer,catalyst,h-BN,graphene,CVD,2D materials,heterostructures,platinum
更新于2025-09-23 15:22:29