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Hot wire chemical vapor deposition for silicon photonics: An emerging industrial application opportunity
摘要： In this work different silicon photonic devices, including straight waveguides, multi-mode interference devices and Mach-Zehnder interferometers, were fabricated and characterized on hot-wire chemical vapor deposition (HWCVD) silicon nitride (SiN) layers deposited at temperatures below 350 °C. These layers presented a hydrogen concentration of 13.1%, which is lower than that achieved with plasma enhanced chemical vapor deposition at these deposition temperatures. The lowest reported optical propagation losses of 6.1 dB/cm and 5.7 dB/cm, 1550 nm and 1310 respectively, for straight SiN waveguides prepared by HWCVD was measured. We demonstrated that silicon nitride SiN, prepared using HWCVD, is a viable material for silicon photonics fabrication.
关键词： Multimode interferometer,Silicon photonics waveguides,Silicon photonics,Hot wire chemical vapor deposition,Silicon nitride,Mach-Zehnder interferometer
更新于2025-11-21 11:20:42
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Hexagonal Boron Nitride Growth on Cu-Si Alloy: Morphologies and Large Domains
摘要： Controllable synthesis of high-quality hexagonal boron nitride (h-BN) is desired toward the industrial application of 2D devices based on van der Waals heterostructures. Substantial efforts are devoted to synthesize h-BN on copper through chemical vapor deposition, which has been successfully applied to grow graphene. However, the progress in synthesizing h-BN has been significantly retarded, and it is still challenging to realize millimeter-scale domains and control their morphologies reliably. Here, the nucleation density of h-BN on Cu is successfully reduced by over two orders of magnitude by simply introducing a small amount of silicon, giving rise to large triangular domains with maximum 0.25 mm lateral size. Moreover, the domain morphologies can be modified from needles, tree patterns, and leaf darts to triangles through controlling the growth temperature. The presence of silicon alters the growth mechanism from attachment-limited mode to diffusion-limited mode, leading to dendrite domains that are rarely observed on pure Cu. A phase-field model is utilized to reveal the growing dynamics regarding B-N diffusion, desorption, flux, and reactivity variables, and explain the morphology evolution. The work sheds lights on the h-BN growth toward large single crystals and morphology probabilities.
关键词： large domain,boron nitride,growth,morphology,chemical vapor deposition
更新于2025-11-21 11:18:25
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Ultrafast Transition of Non-Uniform Graphene to High-Quality Uniform Monolayer Film on Liquid Cu
摘要： It is essentially important to synthesize uniform graphene films with controlled number of layers since their properties strongly depend on the number of layers. Although chemical vapor deposition (CVD) on Cu has been widely used to synthesize large-area graphene films, the growth on solid and liquid Cu suffers from poor thickness uniformity with a great number of adlayers and difficulty in forming continuous film even after a long growth time of hours, respectively. Here, we found that non-uniform graphene film initially grown on solid Cu foil can rapidly transform into continuously uniform monolayer graphene film on liquid Cu within 3 min. Moreover, the films obtained show larger grain size, higher quality, better optical and electrical properties and better performance in organic light-emitting diode (OLED) applications than the original films grown on solid Cu foil. By using carbon isotope labeling, we revealed that the multilayer-to-monolayer transition of graphene on liquid Cu experiences etching-‘self-aligning’-coalescence processes. This two-step CVD method not only opens up a new way for the rapid growth of uniform monolayer graphene films, but also provides helpful information for the controlled growth of uniform monolayers of other 2D materials such as monolayer h-BN.
关键词： film,2D material,chemical vapor deposition,number of layers,graphene
更新于2025-11-14 17:03:37
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Room Temperature Synthesis of Germanium Oxide Nanofilaments and Their Potential Use as Luminescent Self‐Cleaning Surfaces
摘要： Germanium oxide nanofilaments (GNFs) have been synthesized under ambient conditions from the gas phase using germanium tetrachloride as a precursor. Non-crystalline GNFs synthesized by this procedure are 1-10 μm in length and 80-110 nm in diameter applying Droplet Assisted Growth and Shaping (DAGS) Chemistry. The relative humidity has been adjusted at various values in order to demonstrate the crucial role of humidity in the gas phase for the nanofilament synthesis. The novel GNFs show a strong luminescence emission in the ultra-violet and light blue region. In addition, a self-cleaning and superhydrophobic properties could be introduced in the luminescent GNF nanofilaments by simple treatment with silane molecules.
关键词： silicone nanofilaments,chemical vapor deposition,DAGS chemistry,germanium oxide nanofilaments,self-cleaning surfaces
更新于2025-11-14 15:18:02
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Single process CVD growth of hBN/Graphene heterostructures on copper thin films
摘要： In this study, we have successfully grown hBN/graphene heterostructures on copper thin films using chemical vapor deposition in a single process. The first and most surprising result is that graphene grows underneath hBN and adjacent to the Cu film even though it is deposited second. This was determined from cross-sectional TEM analysis and XPS depth profiling, which chemically identified the relative positions of hBN and graphene. The effect of various growth conditions on graphene/hBN heterostructures was also studied. It was found that a pressure of 200 torr and a hydrogen flow rate of 200 sccm (;1 H2/N2) yielded the highest quality of graphene, with full surface coverage occurring after a growth time of 120 min. The resulting graphene films were found to be approximately 6–8 layers thick. The grain size of the nanocrystalline graphene was found to be 15–50 nm varying based on growth conditions.
关键词： XPS depth profiling,copper thin films,TEM analysis,hBN/graphene heterostructures,chemical vapor deposition
更新于2025-11-14 14:32:36
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Device Fabrication Based on Oxidative Chemical Vapor Deposition (oCVD) Synthesis of Conducting Polymers and Related Conjugated Organic Materials
摘要： Conducting polymers (CPs) combine electronic conductivity, optical transparency, and mechanical flexibility compatible with lightweight substrates. Due to these features CPs exhibit promising performance for a wide range of applications including electronic, optoelectronic, electrochemical, optochemical, and energy storage and harvesting devices. Fabrication of high-quality CPs thin film in a large scale is of high demand in multiple industrial sectors. Chemical vapor deposition (CVD) is a promising approach for scale-up and commercialization of CPs in large-scale thin film applications by a roll-to-roll process. The CVD technique is a versatile deposition technique for fabricating CPs due to its unique combination of characteristics, including formation of conformal coatings, processing at low temperatures, solvent-free synthesis, uniformity of growth, mechanical flexible films, industrial scale-up, and substrate-independence. This review focuses primarily on the oxidative CVD technique for the fabrication of CPs and related conjugated polymers by emphasizing on their applications in devices.
关键词： conducting polymers (CPs),oxidative chemical vapor deposition (oCVD),conjugated polymers
更新于2025-09-23 15:23:52
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CVD Diamond
摘要： Diamond has the most extreme properties in mechanical, chemical and physical domain. There are many methods to manufacture synthetic diamond. Diamond layers can be deposited on various materials by many processes. The most robust and preferred method is chemical vapour deposition. A variety of researches have been performed on CVD coatings, and a range of developments has come forth starting from initial publications to the latest results. The process parameters of different CVD techniques have been discussed with technical limitations. Flow rate, applied power, increased pressure and temperature range are important parameters for the deposition of CVD diamond.
关键词： Plasma arrangement,Hot filament,Chemical vapor deposition
更新于2025-09-23 15:23:52
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Growth of graphene on SiO2 with hexagonal boron nitride buffer layer
摘要： One-through process of graphene growth on insulator substrates with inserting a hexagonal boron nitride (h-BN) buffer layer is expected to yield significant improvements in performance of electron transport properties of graphene devices due to the alleviation of the interface interaction between graphene and insulators and the enhancement of the flatness of the substrate. In this study, we successfully fabricated a graphene/h-BN/SiO2 heterostructure by direct chemical vapor deposition (CVD) without mechanical transfer processes. It was found that h-BN promotes the growth of graphene on SiO2 whereas the graphene growth without the h-BN layer is extremely difficult. The electronic structures of graphene and h-BN were investigated by using micro-Raman spectroscopy and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. The B and N K-edge NEXAFS revealed that substitutional oxygen impurities with the chemical form of BN3?xOx (x = 1, 2, 3) are present in both h-BN/SiO2 and graphene/h-BN/SiO2. The number of O substitutional impurities is two times larger in graphene/h-BN/SiO2 than in h-BN/SiO2, which is presumed to be due to the reaction with oxygen from SiO2 and methanol during the graphene growth. The interfacial interaction between graphene and h-BN was found to be weak in graphene/h-BN/SiO2. The present study shows that the h-BN layer grown with CVD can be a superior buffer layer for graphene devices which enables direct graphene growth on it and to decrease the interactions with insulator substrates.
关键词： NEXAFS,h-BN,Chemical vapor deposition,Buffer layer,Graphene
更新于2025-09-23 15:23:52
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Growth Order-Dependent Strain Variations of Lateral Transition Metal Dichalcogenide Heterostructures
摘要： Understanding the heterojunction of a lateral heterostructured transition metal dichalcogenide (hTMD) is important to take advantage of the combined optoelectronic properties of individual TMDs for various applications but, however, is hampered by mingled effects from lattice mismatch and substrate interaction. Here, we systematically investigated the strain occurring at lateral hTMDs consisting of molybdenum disulfide (MoS2) and molybdenum diselenide (MoSe2) prepared by chemical vapor deposition. Comparison of homologous TMDs and hTMDs from controlled growth order revealed systematic change in photoluminescence behavior depending on substrate interaction and relative lattice mismatch. Near the heterojunction, a TMD with a larger lattice constant (a) exhibits photoluminescence (PL) red-shift, whereas a TMD with smaller a shows an opposite trend owing to lattice-induced strain. These effects are augmented in a subtractive or additive manner by tensile strain from the substrate interaction. Moreover, comparison of PLs revealed that the shell region grown from the core edges exhibits weak substrate interaction contrasted by that of a shell region independently grown on a shell. This study provides detailed understandings of the heterojunction at a lateral hTMD for various applications.
关键词： photoluminescence,lateral heterostructure,strain,transition metal dichalcogenides,chemical vapor deposition
更新于2025-09-23 15:23:52
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Chemical vapor deposition of graphene on refractory metals: The attempt of growth at much higher temperature
摘要： Large area graphene is usually grown by chemical vapor deposition on Cu or Ni catalysts at ～1000 °C. For most materials, high temperature leads to high quality. However, graphene growth at even higher temperatures is rarely reported. Therefore, here we systematically investigate the graphene deposition on refractory metals i.e. metals with extremely high melting points. The growth parameters and material characterizations are given in detail. On Ta which readily forms carbides during the carbon deposition, the growth mode is monolayer due to the chemical absorption of excess carbon in the bulk metal. On Re, there is no carbide formed (except in extreme conditions), which greatly simpli?es the scenario. Because of the relatively high carbon solubility in Re, the growth temperature has to be limited in order not to drift into the dominantly multilayer graphene regime caused by the carbon segregation. Graphene with reasonable quality has been achieved, although not as good as expected. For example, on Ta, the residual bonds between the graphene and substrate deteriorate the graphene crystalline quality. Despite the di?culties in refractory metal etching, the transfer technique of the graphene is also explored. This research contributes to the fundamental understanding of the graphene growth theory and technology on refractory metals.
关键词： Refractory metal,Graphene,Chemical vapor deposition,High temperature growth
更新于2025-09-23 15:23:52