低温CVD法制备石墨烯的研究进展（英文）

石墨烯是一种由sp~2杂化碳原子组成的二维碳纳米材料。由于其特殊的性质,在世界范围内引起了广泛的关注和研究。化学气相沉积法(CVD)是制备石墨烯最有效、最常用的方法。然而,传统的CVD石墨烯生长温度非常高(1 000℃),这不仅使得石墨烯制备成本高,而且限制了其在某些领域的应用。因此,低温下石墨烯的合成是目前研究者关注的焦点。前驱体类型(气态、液态、固态)和衬底类型(过渡金属、合金、介质衬底)是影响石墨烯合成温度的重要因素。本文将从以上几个方面对低温条件下CVD合成石墨烯的研究结果进行综述。     

石墨烯的化学气相沉积法制备及其表征

石墨烯是由sp2杂化的碳原子键合而成的具有六边形蜂窝状晶格结构的二维原子晶体,其具有电学、力学和光学等方面一系列优良性能,使得它在各个领域的应用一直被人们所关注。然而,石墨烯的工业化制备仍然面临着巨大的挑战。本文采用化学气相沉积法(CVD)制备石墨烯,并用拉曼光谱、高分辨率扫描电镜和X射线多晶衍射对其进行了分析和表征。研究结果表明,用CVD法制备石墨烯具有工业化的可能。     

北大/香港理工大学单晶石墨烯薄膜生产速度提高150倍技术研发获得成功

正中国科学家在《自然·纳米技术》杂志上发表论文称,他们在单晶石墨烯制备上取得了一项突破。通过对化学气相沉积法(CVD)的调整和改进,他们将石墨烯薄膜生产的速度提高了150倍。新研究为石墨烯的大规模应用奠定了基础。石墨烯是由碳原子构成的只有一层原子厚度的二维晶体材料,在电、光、机械强度上的优异特性,使其在电子学、     

蓝宝石衬底上石墨烯的制备研究

开展了化学气相沉积(CVD)法在蓝宝石衬底上直接生长石墨烯的制备研究和模拟研究,研究衬底表面形貌和生长温度对石墨烯的影响。运用原子力显微镜(AFM)、X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)、拉曼光谱(Raman)、高分辨透射电子显微镜(HRTEM)等对石墨烯生长开展了微结构研究。模拟研究发现,氢气对衬底表面形貌具有重要影响,在H原子的作用下Al—O键被拉长了51.42%,近乎断裂,因而对蓝宝石衬底的表面粗糙度产生影响。实验发现H_2对蓝宝石衬底有刻蚀作用,刻蚀后的蓝宝石衬底表面粗糙度Ra变大,不易于石墨烯生长。随着生长温度的升高,生长的石墨烯质量也逐渐变好。     

三维石墨烯宏观结构材料的制备与应用研究进展

将二维单原子层石墨烯组装成三维宏观结构是石墨烯获得实际应用的最佳途径之一.三维石墨烯(3DG)宏观结构在保留石墨烯本身性质的基础上具有更高比表面积、电导率和更优异的机械性能.近年人们相继提出了模板辅助化学气相沉积(CVD)、自组装、电化学沉积、3D打印等多种方法制备不同结构3DG宏观材料,并在能源、信息、环境、生物医学等方面取得了广泛应用.本文综述了当前3DG的制备方法及其在超级电容器和组织工程领域应用的最新进展.     

化学气相沉积制备大面积高质量石墨烯的研究进展

石墨烯是由单层碳原子紧密堆积形成的一种碳质新材料,具有优良的电学、光学、热学及力学等性质。在众多的石墨烯制备方法中,化学气相沉积(Chemical vapor deposition,CVD)最有可能实现大面积、高质量石墨烯的可控制备。综述了CVD方法制备大面积、高质量石墨烯的影响因素,包括衬底、碳源及生长条件(气体流量、生长温度、等离子体功率、生长压强、沉积时间、冷却速率等)。最后展望了CVD方法制备石墨烯的发展方向。     

衬底对CVD生长石墨烯的影响研究

石墨烯有独特的结构和优异的性能,在电子、信息、能源、材料和生物医药等领域都有着广阔的应用前景。为了更好的应用这种新型材料,如何大规模可控合成高质量石墨烯是一个必须克服的困难。相比与机械剥离法、化学氧化还原法和碳化硅表面外延生长法,化学气相沉积法（CVD）因其可以生长大面积高质量连续石墨烯膜而倍受关注。基于石墨烯的生长机理,从衬底材料的角度,综述了近几年衬底对CVD生长石墨烯的影响的研究进展。展望了衬底选择的发展新趋势。     

六方氮化硼二维材料的制备及光电特性的研究进展

介绍了六方氮化硼(h-BN)材料的几种主要制备方法,如剥离法、化学气相沉积法、水热法等,并讨论了各种制备方法的特点。同时展示了以h-BN二维材料制备的晶体管的特性,发现其具有良好的电学和放大特性。综述了h-BN与石墨烯、硫化钼等其他二维材料构成的异质结的光电特性,因为h-BN带隙宽,与其他二维材料形成的异质结势垒高度增加,载流子复合速率降低,使光电流响应率增加,响应时间减小,从而使器件的频率特性得到显著提升。这些优异特性可用于制备光电探测器和太阳能电池等高效率的纳米光电子器件。最后,还对h-BN未来的发展方向进行了展望,其制备工艺和应用领域还有待进一步深入拓展。     

中国科大揭示石墨烯有序晶界的范霍夫奇异性

正中国科学技术大学侯建国、王兵教授研究组近日利用扫描隧道显微术(STM)研究石墨烯有序晶界,揭示了原子尺度分辨的有序晶界结构,证明了有序晶界中存在范霍夫奇异性(VHS)。相关研究成果发表在《Physical Review Letters》上。晶界是石墨烯材料中的一种结构缺陷,通常是生长过程中各晶粒间取向差异所致,常见于通过化学气相沉积(CVD)生长的较大面积石墨烯。与其他晶体材料相似,石墨烯中晶     

介质阻挡放电化学气相沉积法制备DLC薄膜研究

采用介质阻挡化学气相沉积法(DBD CVD)在Si及石英衬底上、室温下成功的沉积出光滑、致密、均匀、膜基结合较好的类金刚石(DLC)薄膜,并考察了电源电压对类金刚石薄膜结构及性能的影响。拉曼光谱(Raman)、扫描电子显微镜(SEM)、原子力显微镜(AFM)、紫外可见光谱(UV Vis)、高阻仪等测试及分析结果显示DBD CVD 法适于制备高质量硬质DLC薄膜。对DBD放电做了理论分析,结果与工艺研究的结论相符合。     

Direct growth of graphene/hexagonal boron nitride stacked layers

Graphene (G) and atomic layers of hexagonal boron nitride (h-BN) are complementary two-dimensional materials, structurally very similar but with vastly different electronic properties. Recent studies indicate that h-BN atomic layers would be excellent dielectric layers to complement graphene electronics. Graphene on h-BN has been realized via peeling of layers from bulk material to create G/h-BN stacks. Considering that both these layers can be independently grown via chemical vapor deposition (CVD) of their precursors on metal substrates, it is feasible that these can be sequentially grown on substrates to create the G/h-BN stacked layers useful for applications. Here we demonstrate the direct CVD growth of h-BN on highly oriented pyrolytic graphite and on mechanically exfoliated graphene, as well as the large area growth of G/h-BN stacks, consisting of few layers of graphene and h-BN, via a two-step CVD process. The G/h-BN film is uniform and continuous and could be transferred onto different substrates for further characterization and device fabrication.     

Synthesis of monolayer hexagonal boron nitride on Cu foil using chemical vapor deposition

Hexagonal boron nitride (h-BN) is very attractive for many applications, particularly, as protective coating, dielectric layer/substrate, transparent membrane, or deep ultraviolet emitter. In this work, we carried out a detailed investigation of h-BN synthesis on Cu substrate using chemical vapor deposition (CVD) with two heating zones under low pressure (LP). Previous atmospheric pressure (AP) CVD syntheses were only able to obtain few layer h-BN without a good control on the number of layers. In contrast, under LPCVD growth, monolayer h-BN was synthesized and time-dependent growth was investigated. It was also observed that the morphology of the Cu surface affects the location and density of the h-BN nucleation. Ammonia borane is used as a BN precursor, which is easily accessible and more stable under ambient conditions than borazine. The h-BN films are characterized by atomic force microscopy, transmission electron microscopy, and electron energy loss spectroscopy analyses. Our results suggest that the growth here occurs via surface-mediated growth, which is similar to graphene growth on Cu under low pressure. These atomically thin layers are particularly attractive for use as atomic membranes or dielectric layers/substrates for graphene devices.     

Wafer-Scale Single Crystal Hexagonal Boron Nitride Layers Grown by Submicron-Spacing Vapor Deposition

The direct growth of wafer-scale single crystal two-dimensional (2D) hexagonal boron nitride (h-BN) layer with a controllable thickness is highly desirable for 2D-material-based device applications. Here, for the first time, a facile submicron-spacing vapor deposition (SSVD) method is reported to achieve 2-inch single crystal h-BN layers with controllable thickness from monolayer to tens of nanometers on the dielectric sapphire substrates using a boron film as the solid source. In the SSVD growth, the boron film is fully covered by the same-sized sapphire substrate with a submicron spacing, leading to an efficient vapor diffusion transport. The epitaxial h-BN layer exhibits extremely high crystalline quality, as demonstrated by both a sharp Raman E_2g vibration mode (12 cm⁻¹) and a narrow X-ray rocking curve (0.10°). Furthermore, a deep ultraviolet photodetector and a ZrS₂/h-BN heterostructure fabricated from the h-BN layer demonstrate its fascinating properties and potential applications. This facile method to synthesize wafer-scale single crystal h-BN layers with controllable thickness paves the way to future 2D semiconductor-based electronics and optoelectronics.     

Recent Advances in Growth of Large‐Sized 2D Single Crystals on Cu Substrates

Large‐scale and high‐quality 2D materials have been an emerging and promising choice for use in modern chemistry and physics owing to their fascinating property profile. The past few years have witnessed inspiringly progressing development in controlled fabrication of large‐sized and single‐crystal 2D materials. Among those production methods, chemical vapor deposition (CVD) has drawn the most attention because of its fine control over size and quality of 2D materials by modulating the growth conditions. Meanwhile, Cu has been widely accepted as the most popular catalyst due to its significant merit in growing monolayer 2D materials in the CVD process. Herein, very recent advances in preparing large‐sized 2D single crystals on Cu substrates by CVD are presented. First, the unique features of Cu will be given in terms of ultralow precursor solubility and feasible surface engineering. Then, scaled growth of graphene and hexagonal boron nitride (h‐BN) crystals on Cu substrates is demonstrated, wherein different kinds of Cu surfaces have been employed. Furthermore, the growth mechanism for the growth of 2D single crystals is exhibited, offering a guideline to elucidate the in‐depth growth dynamics and kinetics. Finally, relevant issues for industrial‐scale mass production of 2D single crystals are discussed and a promising future is expected.     

Nano- and microstructuring of graphene using UV-NIL

In this work we demonstrate for the first time the micro-?and nanostructuring of graphene by means of UV-nanoimprint lithography. Exfoliated graphene on SiO(2) substrates, as well as graphene deposited by chemical vapor deposition (CVD) on polycrystalline nickel and copper, and transferred CVD graphene on dielectric substrates, were used to demonstrate that our technique is suitable for large-area patterning (2?×?2?cm(2)) of graphene on various types of substrates. The demonstrated fabrication procedure of micrometer as well as nanometer-sized graphene structures with feature sizes down to 20?nm by a wafer-scale process opens up an avenue for the low-cost and high-throughput manufacturing of graphene-based optical and electronic applications. The processed graphene films show electron mobilities of up to 4.6?×?10(3)?cm(2)?V (-1)?s(-1), which confirms them to exhibit state-of-the-art electronic quality with respect to the current literature.     

Large-area vapor-phase growth and characterization of MoS(2) atomic layers on a SiO(2) substrate

Atomic-layered MoS(2) is synthesized directly on SiO(2) substrates by a scalable chemical vapor deposition method. The large-scale synthesis of an atomic-layered semiconductor directly on a dielectric layer paves the way for many facile device fabrication possibilities, expanding the important family of useful mono- or few-layer materials that possess exceptional properties, such as graphene and hexagonal boron nitride (h-BN).     

Direct Growth of Highly Stable Patterned Graphene on Dielectric Insulators using a Surface‐Adhered Solid Carbon Source

A novel method is described for the direct growth of patterned graphene on dielectric substrates by chemical vapor deposition (CVD) in the presence of Cu vapor and using a solid aromatic carbon source, 1,2,3,4‐tetraphenylnapthalene (TPN), as the precursor. The UV/O₃ treatment of the TPN film both crosslinks TPN and results in a strong interaction between the substrate and the TPN that prevents complete sublimation of the carbon source from the substrate during CVD. Substrate‐adhered crosslinked TPN is successfully converted to graphene on the substrate without any organic contamination. The graphene synthesized by this method shows excellent mechanical and chemical stability. This process also enables the simultaneous patterning of graphene materials, which can thus be used as transparent electrodes for electronic devices. The proposed method for the synthesis directly on substrates of patterned graphene is expected to have wide applications in organic and soft hybrid electronics.     

Oxygen-suppressed selective growth of monolayer hexagonal boron nitride on copper twin crystals

Controlled growth of hexagonal boron nitride (h-BN) with desired properties is essential for its wide range of applications.Here,we systematically carried out the chemical vapor deposition of monolayer h-BN on Cu twin crystals.It was found that h-BN nucleated and grew preferentially and simultaneously on the narrow twin crystal strips present in the Cu substrates.The density functional theory calculations revealed that the introduction of oxygen could efficiently tune the selectivity.This is because of the reduction in the dehydrogenation barrier of the precursor molecules by the introduction of oxygen.Our findings throw light on the direct growth of functional h-BN nanoribbons on nano-twinned crystal strips and switching of the growth behavior of h-BN films by oxygen.     

Large-scale synthesis of high-quality hexagonal boron nitride nanosheets for large-area graphene electronics

Hexagonal boron nitride (h-BN) has received a great deal of attention as a substrate material for high-performance graphene electronics because it has an atomically smooth surface, lattice constant similar to that of graphene, large optical phonon modes, and a large electrical band gap. Herein, we report the large-scale synthesis of high-quality h-BN nanosheets in a chemical vapor deposition (CVD) process by controlling the surface morphologies of the copper (Cu) catalysts. It was found that morphology control of the Cu foil is much critical for the formation of the pure h-BN nanosheets as well as the improvement of their crystallinity. For the first time, we demonstrate the performance enhancement of CVD-based graphene devices with large-scale h-BN nanosheets. The mobility of the graphene device on the h-BN nanosheets was increased 3 times compared to that without the h-BN nanosheets. The on-off ratio of the drain current is 2 times higher than that of the graphene device without h-BN. This work suggests that high-quality h-BN nanosheets based on CVD are very promising for high-performance large-area graphene electronics.     

MoS<Subscript>2</Subscript>/h-BN heterostructures: controlling MoS<Subscript>2</Subscript> crystal morphology by chemical vapor deposition

Tuning the properties of van der Waals heterostructures based on alternating layers of two-dimensional materials is an emerging field of research with implications for electronics and photonics. Hexagonal boron nitride (h-BN) is an attractive insulating substrate for two-dimensional materials as it may exert less influence on the layer’s properties than silica. In this work, MoS₂ layers were deposited by chemical vapor deposition (CVD) on thick h-BN flakes mechanically exfoliated deposited on Si/SiO₂ substrates. CVD affords the controllable, large-scale preparation of MoS₂ on h-BN alleviating shortcomings of manual mechanical assembly of such heterostructures. Electron microscopy revealed that in-plane and vertical to the substrate MoS₂ layers were grown at high yield, depending on the sample preparation conditions. Raman and photoluminescence spectroscopy were employed to assess the optical and electronic quality of MoS₂ grown on h-BN as well as the interactions between MoS₂ and the supporting substrate. Compared to silica, MoS₂ layers grown on h-BN are less prone to oxidation and are subjected to considerably weaker electronic perturbation.