Scalable production of single 2D van der Waals layers through atomic layer deposition: Bilayer silica on metal foils and films
Gregory S. Hutchings, Xin Shen, Chao Zhou, Petr Dementyev, Daniil Naberezhnyi, Inga Ennen, Andreas Hütten, Nassar Doudin, Jesse Hsu, Zachary S. Fishman, Udo D. … 展开作者
Gregory S. Hutchings, Xin Shen, Chao Zhou, Petr Dementyev, Daniil Naberezhnyi, Inga Ennen, Andreas Hütten, Nassar Doudin, Jesse Hsu, Zachary S. Fishman, Udo D. Schwarz, Shu Hu, Eric I. Altman
The self-limiting nature of atomic layer deposition (ALD) makes it an appealing option for growing single layers of two-dimensional van der Waals (2D-VDW) materials. In this paper it is demonstrated that a single layer of a 2D-VDW form of SiO2 can be grown by ALD on Au and Pd polycrystalline foils and epitaxial films. The silica was deposited by two cycles of bis (diethylamino) silane and oxygen plasma exposure at 525 K. Initial deposition produced a three-dimensionally disordered silica layer; however, subsequent annealing above 950 K drove a structural rearrangement resulting in 2D-VDW; this annealing could be performed at ambient pressure. Surface spectra recorded after annealing indicated that the two ALD cycles yielded close to the silica coverage obtained for 2D-VDW silica prepared by precision SiO deposition in ultra-high vacuum. Analysis of ALD-grown 2D-VDW silica on a Pd(111) film revealed the co-existence of amorphous and incommensurate crystalline 2D phases. In contrast, ALD growth on Au(111) films produced predominantly the amorphous phase while SiO deposition in UHV led to only the crystalline phase, suggesting that the choice of Si source can enable phase control.
A novel route for the synthesis of large area graphene by an indigenously built electron cyclotron resonance (ECR) plasma enhanced chemical vapor deposition (PECVD) setup has been reported in this work. A unique 2.45 GHz permanent magnet type ECR PECVD system has been designed and developed for the growth of various nano-structures and films. The apparatus has a unique advantage to synthesize large area graphene at much lower additional substrate heating than heat supplied by an external oven in conventional thermal CVD method. A major amount of heat is supplied here by ECR plasma. Polycrystal…
This report introduces the electromagnetic absorption of the catalyst as a novel knob in optimizing chemical vapor deposition of graphene. A chromium film initially deposited at one side of a catalyst copper foil absorbs radiative thermal energy several times higher than the plain copper foil and migrates to the other side of the foil in the form of microscale grains. The process involves local melting of the copper which together with the increased operation temperature, improves the crystalline quality of growing graphene. Local melting of copper replaces the otherwise-necessary annealing pr…
In this paper the early stages of the self-catalyzed Vapor-Liquid-Solid (VLS) growth of GaAs nanowires on epi-ready Si substrates by Molecular Beam Epitaxy (MBE) are studied. The interaction of Ga nano-droplets (NDs) with the silica overlayer is investigated by X-ray Photoemission Spectroscopy (XPS) and Atomic Force Microscopy (AFM). We show how Ga NDs drill the silica overlayer and make contact with bulk Si to allow GaAs nanowires (NWs) epitaxial growth by studying each of the three steps of the NW growth process sequentially: Ga NDs pre-deposition, post-deposition annealing to reach the NW g…
Two dimensional materials are an emerging class of materials which is transforming the present day research activity on a phenomenal scale. Hexagonal boron nitride is a wide band gap 2D material which is an excellent substrate for graphene based electronics. To achieve the full potential of hBN scalable and high yield growth procedures are required. Here, we demonstrate the synthesis of hBN by reactive R.F magnetron sputtering over copper foil. Copper foil preparation conditions determines the phase selectivity of BN films. Deposition of hBN on non-electropolished Cu foils with predominant (10…
Large-Area Synthesis of High-Quality and Uniform Graphene Films on Copper Foils
石墨烯因其独特的能带结构和物理性质而引起人们极大的兴趣。如今，石墨烯仅限于小尺寸，因为它主要通过剥离石墨来生产。我们使用甲烷通过化学气相沉积在铜衬底上生长了厘米级的大面积石墨烯薄膜。该膜主要是单层石墨烯，其中小百分比（小于5%）的面积具有很少的层，并且在铜表面台阶和晶界上是连续的。碳在铜中的低溶解度似乎有助于使这种生长过程自我限制。我们还开发了石墨烯膜转移到任意衬底的工艺，并且在Si/SiO2衬底上制造的双栅场效应晶体管在室温下显示出高达4050 cm 2 V-1 s-1的电子迁移率。
The growth of single-layer graphene (SLG) by chemical vapor deposition (CVD) on copper surfaces is very popular because of the self-limiting effect that prevents the growth of few-layer graphene (FLG). However, the reproducibility of the CVD growth of homogeneous SLG remains a major challenge, especially if one wants to avoid heavy surface treatments, monocrystalline substrates and expensive equipment to control the atmosphere inside the growth system. We demonstrate here that backside tungsten coating of copper foil allows the exclusive growth of SLG with full coverage by atmospheric pressure…
The authors report in situ Auger electron spectroscopy (AES) of the surfaces of complex oxides thin films grown by pulsed laser deposition (PLD). The authors demonstrate the utility of the technique in studying chemical composition by collecting characteristic Auger spectra of elements from samples such as complex oxide thin films and single crystals as well as metal foils. In the case of thin films, AES studies can be performed with single unit cell precision by monitoring thickness during deposition with reflection high energy electron diffraction (RHEED). The authors address some of the cha…
We report one-pot chemical vapor deposition (CVD) growth of large-area Janus SeMoS monolayers, with the asymmetric top (Se) and bottom (S) chalcogen atomic planes with respect to the central transition metal (Mo) atoms. The formation of these two-dimensional semiconductor monolayers takes place upon the thermodynamic equilibrium-driven exchange of the bottom Se atoms of the initially grown MoSe2 single crystals on gold foils with S atoms. The growth process is characterized by complementary experimental techniques including Raman and X-ray photoelectron spectroscopy and the growth mechanisms a…
Due to the rapid growth in the demand for high-energy-density Li batteries and insufficient global Li reserves, the anode-free Li metal batteries are receiving increasing attention. Various strategies, such as surface modification and structural design of Cu current collectors, have been proposed to stabilize the anode-free Li metal batteries. Unfortunately, the mechanism of Li deposition on the Cu surfaces with the different Miller indices is poorly understood, especially on the atomic scale. Here, a large-scale molecular dynamics simulation of Li deposition on the Cu substrates was performed…
New approach for obtaining ceramic NASICON (Na$_3$Zr$_2$ (SiO$_4$)$_2$PO$_4$) films sintered in situ by a sol-gel method, using spray deposition and Near-Infra Red Sintering
Graphene layers grown by chemical vapour deposition (CVD) method and transferred from Cu-foils to the oxidized Si-substrates were investigated by spectroscopic ellipsometry (SE), Raman and X-Ray Photoelectron Spectroscopy (XPS) methods. The optical properties of transferred CVD graphene layers do not always correspond to the ones of the exfoliated graphene due to the contamination from the chemicals used in the transfer process. However, the real thickness and the mean properties of the transferred CVD graphene layers can be found using ellipsometry if a real thickness of the SiO2 layer is tak…
Two-dimensional hexagonal boron nitride (h-BN) single crystals with various shapes have been synthesized by chemical vapor deposition over the past several years. Here we report the formation of three-leaf dart (3LD)-shaped single crystals of h-BN on Cu foil by atmospheric-pressure chemical vapor deposition. The leaves of the 3LD-shaped h-BN are as long as 18 μm and their edges are smooth armchair on one side and stepped armchair on the other. Careful analysis revealed that surface oxygen plays an important role in the formation of the 3LD shape. Oxygen suppressed h-BN nucleation by passivatin…
Rhombohedral-stacked few-layer graphene (FLG) has been receiving an ever-increasing attention owing to its peculiar electronic properties that could lead to enticing phenomena such as superconductivity and magnetic ordering. Up to now, experimental studies on such material have been mainly limited by the difficulty in isolating it in thickness exceeding 3 atomic layers with device-compatible size. In this work, rhombohedral graphene with thickness up to 9 layers and areas up to ~50 micrometers square is grown via chemical vapor deposition (CVD) on suspended Cu foils and transferred onto target…
Hexagonal boron nitride (h-BN) is well-established as a requisite support, encapsulant and barrier for 2D material technologies, but also recently as an active material for applications ranging from hyperbolic metasurfaces to room temperature single-photon sources. Cost-effective, scalable and high quality growth techniques for h-BN layers are critically required. We utilise widely-available iron foils for the catalytic chemical vapour deposition (CVD) of h BN and report on the significant role of bulk dissolved species in h-BN CVD, and specifically, the balance between dissolved oxygen and ca…
This work investigates the growth of B-C-N layers by chemical vapor deposition using methylamine borane (MeAB) as single-source precursor. MeAB has been synthesized and characterized, paying particular attention to the analysis of its thermolysis products, which are the gaseous precursors for B-C-N growth. Samples have been grown on Cu foils and transferred onto different substrates for their morphological, structural, chemical, electronic and optical characterizations. The results of these characterizations indicate a segregation of h-BN and Graphene-like (Gr) domains. However, there is an im…
Graphene films with large domain size by a two-step chemical vapor deposition process
石墨烯的基本性质使其成为一种有吸引力的材料，用于各种应用。已经开发了各种技术来生产石墨烯，最近我们发现通过在Cu箔上化学气相沉积（CVD）甲烷来合成大面积石墨烯。我们还表明，石墨烯在Cu上的生长是一个表面介导的过程，并且膜是多晶的，具有数十平方微米的区域。在本文中，我们报告的生长参数，如温度，甲烷流量和分压上的生长速率，域的大小，和表面覆盖的石墨烯的拉曼光谱，透射和扫描电子显微镜确定的效果。基于这些结果，我们开发了两步CVD工艺来合成具有数百平方微米面积的畴的石墨烯膜。扫描电子显微镜和拉曼光谱清楚地表明，通过改变生长参数的域尺寸的增加。透射电子显微镜进一步显示，畴相对于彼此以约13度至近30度的角度范围结晶旋转。对背栅FET进行的电输运测量表明，具有较大畴的整体膜倾向于具有较高的载流子迁移率，在室温下高达约16，000 cm 2 V-1 s-1。
Hexagonal boron nitride (h-BN) is unique among two-dimensional materials, with a large band gap (~6 eV) and high thermal conductivity (>400 W/m/K), second only to diamond among electrical insulators. Most electronic studies to date have relied on h-BN exfoliated from bulk crystals; however, for scalable applications the material must be synthesized by methods such as chemical vapor deposition (CVD). Here, we demonstrate single- and few-layer h-BN synthesized by CVD on single crystal platinum and on carbon nanotube (CNT) substrates, also comparing these films with h-BN deposited on the more com…
Black body materials prove promising candidates to meet future energy demands as they are able to harvest energy from the total bandwidth of solar radiation. Here, we report on high absorption (> 98 %) near-black body-like structures consisting of a silica scaffold and Ag nanoparticles with a layer thickness below 10 um; fabricated using metastable atomic layer deposition (MS-ALD) and to be applied for a wide solar spectrum ranging from 220 nm to 2500 nm. Several effects contribute collectively and in a synergistic manner to the high absorbance, including the pronounced heterogeneity of the na…
Digital Image Correlation (DIC) is of vital importance in the field of experimental mechanics, yet, producing suitable DIC patterns for demanding in-situ mechanical tests remains challenging, especially for ultra-fine patterns, despite the large number of patterning techniques in the literature. Therefore, we propose a simple, flexible, one-step technique (only requiring a conventional deposition machine) to obtain scalable, high-quality, robust DIC patterns, suitable for a range of microscopic techniques, by deposition of a low melting temperature solder alloy in so-called 'island growth' mod…
Microstructured optical waveguides (MOW) are of great interest for chemical and biological sensing. Due to the high overlap between a guiding light mode and an analyte filling of one or several fiber capillaries, such systems are able to provide strong sensitivity with respect to variations in the refractive index and the thickness of filling materials. Here, we introduce a novel type of functionalized MOWs whose capillaries are coated by a layer-by-layer (LBL) approach, enabling the alternate deposition of silica particles (SiO2) at different diameters - 300 nm, 420 nm, and 900 nm - and layer…
Elastic and structural anisotropy in silica thin films for gravitational-wave detectors
Università di Perugia（佩鲁贾大学）；Istituto Nazionale di Fisica Nucleare, Sezione di Perugia（意大利国家核物理研究所佩鲁贾分部）；Università di Genova（热那亚大学）；Istituto Nazionale di Fisica Nucleare, Sezione di Genova（意大利国家核物理研究所热那亚分部）；CNR - Istituto di Fotonica e Nanotecnologie (IFN)（国家研究委员会光子学与纳米技术研究所）；Università di Padova（帕多瓦大学）；Université de Lyon（里昂大学）；Université Claude Bernard Lyon 1（里昂第一大学）；Università di Camerino（卡梅里诺大学）
