石墨烯的化学气相沉积法制备

化学气相沉积(CVD)法是近年来发展起来的制备石墨烯的新方法,具有产物质量高、生长面积大等优点,逐渐成为制备高质量石墨烯的主要方法.通过简要分析石墨烯的几种主要制备方法(胶带剥离法、化学剥离法、SiC外延生长法和CVD方法)的原理和特点,重点从结构控制、质量提高以及大面积生长等方面评述了CVD法制备石墨烯及其转移技术的研究进展,并展望了未来CVD法制备石墨烯的可能发展方向,如大面积单晶石墨烯、石墨烯带和石墨烯宏观体的制备与无损转移等.     

微波等离子体化学气相沉积法制备石墨烯的研究进展

微波等离子体化学气相沉积（MPCVD）法具有低温生长、基底材料选择广泛、容易掺杂等优点,是大面积、高速率、高质量石墨烯制备的首选。首先通过比较制备石墨烯的几种主要CVD方法得出MPCVD法的优势,然后阐述了MPCVD法制备石墨烯的研究,最后介绍了MPCVD法制备的石墨烯的应用并对MPCVD法制备石墨烯的发展趋势进行了展望。     

铜镍合金催化制备大面积均匀的少层石墨烯

少层(1~5层)大面积均匀石墨烯的可控制备,是实现石墨烯在逻辑器件和透明导电电极中使用的关键。本工作使用常压化学气相沉积(CVD)方法,在铜镍合金基底上生长出少数层大面积均匀石墨烯。通过调节铜镍合金的厚度以及控制生长过程中的温度、时间、碳源浓度,本工作实现了层数可控石墨烯的制备。光学显微术、拉曼光谱、紫外可见吸收光谱、高分辨率透射电镜表征结果表明:制备出的石墨烯是大面积均匀的高质量少层石墨烯。     

化学气相沉积法制备大面积石墨烯及其光谱学表征

化学气相沉积（CVD）法是近年来发展起来的制备石墨烯的新方法。该方法产物具有生长面积大、质量高等优点,逐渐成为制备石墨烯的主要方法。用CVD法在常压下通过全面优化实验参量,以镍箔为基底制备了大面积少数层和单层石墨烯,用拉曼光谱,场发射扫描电子显微镜（SEM）和原子力显微镜（AFM）手段表征,通过分析常压下不同温度、不同载气成分比等实验参数,最终获得制备高质量、大面积、少数层石墨烯的最佳参量,用双共振理论解释少数层和单层石墨烯的拉曼光谱中2D峰强度随石墨烯层数变化而变化的原理。CVD法制备的石墨烯具有面积大、低成本、可测量性强、可用于大批量生产的优点,为工业用途石墨烯的制备提供了有效途径。     

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。     

自组装单晶石墨烯阵列的制备

正化学气相沉积法(chemical vapor deposition,CVD)由于成本低、可控性好、可大规模量产等优点近年来被广泛应用与石墨烯的制备中。但是,对于采用CVD方法以固态铜箔作为金属催化剂制备的大面积连续均匀的单层石墨烯薄膜来说,石墨烯晶界较多,质量不高,极大地影响了石墨烯的进一步大规模应用。     

CVD法制备石墨烯中碳源材料的研究进展

大尺寸和晶体结构完整的单层和多层石墨烯的高效制备方法对其工业化生产和大范围应用具有重要意义。化学气相沉积法(CVD)是合成高质量石墨烯薄膜的最有前途的方法。综述了通过常规CVD法或改良CVD法,如等离子体增强CVD法(PE-CVD),制备单层或多层石墨烯所用的固体(S)、液体(L)和气体(G)碳源的先进研究活动和最新进展。     

铜箔表面化学气相沉积少层石墨烯

利用化学气相沉积法(CVD法),在金属基底上生长大面积、少层数和高质量的石墨烯是近年来研究的热点。本研究采用CVD法,在常压高温条件下,以氩气为载体、氢气为还原气体、乙烯为碳源,在铜箔表面生长石墨烯。通过扫描电子显微图(SEM)、X射线衍射仪(XRD)和拉曼图谱(Raman)分析,发现铜箔表面质量和石墨烯的生长时间对石墨烯的层数和缺陷有较大影响。用20%的盐酸去除铜箔表面的保护膜和Cu_2O等杂质,铜箔在1000℃下退火60min可以使铜箔晶粒尺寸增大以及改善铜箔表面的形貌。研究发现生长时间为60s和90s时,制备的石墨烯薄膜对称性良好且层数较少。其中,生长时间为90s时,拉曼表征石墨烯的I_D/I_G值为0.7,表明其缺陷比较少。     

《自然》《科学》8月材料科学前沿要闻

正1.连续供氧辅助下的单晶石墨烯超快生长原标题:Ultrafast growth of single-crystal gra-phene assisted by a continuous oxygen supply石墨烯具有一系列独特的物理性质,可以用于各种电子、光子和光伏发电器件。大多数的应用需要大面积高质量的石墨烯薄膜。在铜表面利用化学气相沉积法(CVD)合成石墨烯的     

原位石墨烯包覆金属复合颗粒的制备与表征

分别采用普通化学气相沉积(CVD)和等离子体增强化学气相沉积(PECVD)在镍粉体颗粒上生长石墨烯的方法,制备出原位石墨烯包覆镍复合颗粒。采用扫描电子显微镜、能谱仪及拉曼光谱仪对两种方法制备的原位石墨烯包覆镍复合颗粒表面石墨烯的形态、分布、结晶质量等特征进行较为系统的测试表征。结果表明,普通CVD法制备的石墨烯沿镍颗粒表面面内生长,较为均匀地包覆着镍颗粒,具有较多褶皱,且石墨烯结晶质量高,缺陷少;PECVD法制备的镍颗粒表面的石墨烯片经较小,呈散乱分布,结晶质量不高,含有缺陷较多。     

Recent trends in graphene materials synthesized by CVD with various carbon precursors

Graphene is a single layer of carbon atoms arranged in an sp²-hybridized structure with properties far superior compared to other materials. Research and development in graphene synthesis have been rapidly growing the past few years, especially using chemical vapor deposition (CVD) over various types of carbon precursor. The nature and the type of carbon precursor is one important parameter of growth by CVD, especially for graphene production, since they can dramatically impact graphene growth yield and rate. However, effects of the used carbon precursor on graphene growth mechanisms are rarely discussed. In the course of large-scale and low-cost graphene preparation, this review on the recent trends regarding the utilization of diverse carbon precursors used to synthesize graphene via the CVD method is of great interest for development of improved or alternative synthesis methods. The details and the mechanisms involved in graphene synthesis using carbon precursors in the form of gaseous, liquids and solids are compared, analyzed and discussed thoroughly. In this review, we present a thorough overview on the impact and mechanisms of carbon precursors in achieving high-quality graphene with competitive edge in the near future.     

铜基底化学气相沉积石墨烯的研究现状与展望

采用粉末包埋法在中国低活性铁素体马氏体钢（RAFM）基底上制备了低活性渗铝层,利用扫描电镜（SEM）和能谱分析（EDS）对渗铝层的形貌和成分进行了分析。结果表明：低活性渗铝层表面铝含量（原子分数）约40％,主要由厚度为15-20μm的FeAl、Fe3-Al及α-Fe（Al）相组成,该渗铝层表面易发生烧结。为避免表面烧结...     

A critical review on the contributions of chemical and physical factors toward the nucleation and growth of large-area graphene

Since the first isolation of graphene over a decade ago, research into graphene has exponentially increased due to its excellent electrical, optical, mechanical and chemical properties. Graphene has been shown to enhance the performance of various electronic devices. In addition, graphene can be simply produced through chemical vapor deposition (CVD). Although the synthesis of graphene has been widely researched, especially for CVD growth method, the lack of understanding on various synthetic parameters still limits the fabrication of large-area and defect-free graphene films. This report critically reviews various parameters affecting the quality of CVD-grown graphene to understand the relationship between these parameters and the choice of metal substrates and to provide a point of reference for future studies of large-area, CVD-grown graphene.     

Layer-by-layer growth of graphene layers on graphene substrates by chemical vapor deposition

We demonstrate a synthesis of graphene layers on graphene templates prepared by the mechanical exfoliation of graphite crystals using a developed chemical vapor deposition (CVD) apparatus that has a furnace with three temperature zones and can regulate the temperatures separately in each zone. This results in individual control over the decomposition reaction of the carbon feedstock and the growth of graphene layers by activated carbon species. CVD growth using multi-temperature zones provides wider temperature windows appropriate to grow graphene layers. We observed that graphene layers proceed by a layer-by-layer growth mode using an optical microscopy, an atomic force microscopy, and Raman spectroscopy. This result suggests that a graphene growth technique using the CVD apparatus is a potential approach for making graphene sheets with precise control of the layer numbers.     

Facile one-step transfer process of graphene

Chemical vapour deposition (CVD) is emerging as a popular method for growing large-area graphene on metal substrates. For transferring graphene to other substrates the technique generally used involves deposition of a polymer support with subsequent etching of the metal substrate. Here we report a simpler one-step transfer process. Few-layer graphene (FLG) grown on a Cu substrate were transferred to a silanized wafer by just pressing them together. Hydrogen bonding between the hydroxyl group on FLG and the amine group on silane molecules facilitate the transfer.     

Molecular absorption and photodesorption in pristine and functionalized large-area graphene layers

We studied the photodesorption behavior of pristine and nitric acid (HNO(3)) treated graphene layers fabricated by chemical vapor deposition (CVD). The decrease in electrical conductivity and a negative shift of the Dirac point in graphene layers illuminated with ultraviolet light are caused by molecular photodesorption, while the UV illumination does not degrade the carrier mobility of graphene layers. When graphene layers were treated with concentrated HNO(3), the photodesorption-induced current decrease became less significant than for pristine graphene layers. We suggest this is due to the passivation of oxygen-bearing functionalities to CVD grown graphene structural defects by HNO(3) functionalization, which prevents the further absorption of gas molecules. Our results provide a new strategy for stabilizing the electrical performance of CVD grown large-area graphene layers for applications ranging from nanoelectronics to optoelectronics.     

Remote catalyzation for direct formation of graphene layers on oxides

Direct deposition of high-quality graphene layers on insulating substrates such as SiO(2) paves the way toward the development of graphene-based high-speed electronics. Here, we describe a novel growth technique that enables the direct deposition of graphene layers on SiO(2) with crystalline quality potentially comparable to graphene grown on Cu foils using chemical vapor deposition (CVD). Rather than using Cu foils as substrates, our approach uses them to provide subliming Cu atoms in the CVD process. The prime feature of the proposed technique is remote catalyzation using floating Cu and H atoms for the decomposition of hydrocarbons. This allows for the direct graphitization of carbon radicals on oxide surfaces, forming isolated low-defect graphene layers without the need for postgrowth etching or evaporation of the metal catalyst. The defect density of the resulting graphene layers can be significantly reduced by tuning growth parameters such as the gas ratios, Cu surface areas, and substrate-to-Cu distance. Under optimized conditions, graphene layers with nondiscernible Raman D peaks can be obtained when predeposited graphite flakes are used as seeds for extended growth.     

Topology evolution of graphene in chemical vapor deposition, a combined theoretical/experimental approach toward shape control of graphene domains

Morphology control of thin film relies on understanding multiple ongoing processes during deposition and growth. To reveal the shape evolution of graphene domains on copper surfaces in chemical vapor deposition (CVD), a combinative study is performed on the CVD growth of graphene on copper surfaces. To identify the factors that influence the adsorption and diffusion of carbon atoms and further determine the domain shape, simulations based on kinetic Monte Carlo techniques are carried out. The results reveal the dependence of the graphene domain shapes on the crystalline orientation of the underlying copper substrate surfaces.     

Thermal stability of multilayer graphene films synthesized by chemical vapor deposition and stained by metallic impurities

Thermal stability is an important property of graphene that requires thorough investigation. This study reports the thermal stability of graphene films synthesized by chemical vapor deposition (CVD) on catalytic nickel substrates in a reducing atmosphere. Electron microscopies, atomic force microscopy, and Raman spectroscopy, as well as electronic measurements, were used to determine that CVD-grown graphene films are stable up to 700?°C. At 800?°C, however, graphene films were etched by catalytic metal nanoparticles, and at 1000?°C many tortuous tubular structures were formed in the film and carbon nanotubes were formed at the film edges and at catalytic metal-contaminated sites. Furthermore, we applied our pristine and thermally treated graphene films as active channels in field-effect transistors and characterized their electrical properties. Our research shows that remnant catalytic metal impurities play a critical role in damaging graphene films at high temperatures in a reducing atmosphere: this damage should be considered in the quality control of large-area graphene films for high temperature applications.     

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.