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We synthesized poly-trimethoxyphenylsilane (PTMS) and applied it as the carrier film to CVD graphene transfer process for the first time. Since the PTMS particles are not fully crosslinked due to the presence of bulky groups, they do not have crystallinity in the long-range order on the graphene surface and are easily removed by solvent such as toluene. Raman, AFM, and X-ray photoemission (especially, Si 2p signal) analysis confirmed that the surface of the transferred graphene was clean without PTMS impurities. [ABSTRACT FROM AUTHOR]

We present a contactless strategy based on bipolar electrochemistry for the local chemical modification of monolayer graphene sheets supported on a substrate. Specifically, peripheral graphene regions are directly modified by copper nanoparticles, the characteristics of which are controllable through the bipolar deposition parameters. This functionalization route provides access to hybrid monolayer graphene modified, for example, with two different metals on opposing peripheries. The presented strategy constitutes a new way to functionalize graphene and an avenue for systematically studying bipolar electrochemistry at the nanoscale. [ABSTRACT FROM AUTHOR]

We report helium diffraction from graphene grown by chemical vapour deposition (CVD) using copper foil. This method reveals acoustic phonons, which are physically important to thermal conductance as well as a sensitive probe of graphene's interactions with the underlying substrate. Helium diffraction is made possible by the high quality of graphene produced by a recently reported “peel-off method”. The graphene lattice parameter was found to remain constant in the temperature range between 110 and 500 K. The measured parabolic dispersion of the flexural mode along Γ ¯ M ¯ allows determining the bending rigidity k = (1.30 ± 0.15) eV, and the graphene–Cu coupling strength g = (5.7 ± 0.4) × 10 19  N/m 3 . Unlike analytics employing atomic resolution microscopy, we obtain information on the atomic-scale quality of the graphene over mm length scales, suggesting the potential for Helium atom scattering to become an important tool for controlling the quality of industrially produced graphene. [ABSTRACT FROM AUTHOR]

Chemical vapor deposition of graphene on transition metals is the most favored method to get large scale homogenous graphene films to date. However, this method involves a very critical step of transferring as grown graphene to desired substrates. A sacrificial polymer film is used to provide mechanical and structural support to graphene, as it is detached from underlying metal substrate, but, the residue and cracks of the polymer film after the transfer process affects the properties of the graphene. Herein, a simple mixture of polystyrene and low weight plasticizing molecules is reported as a suitable candidate to be used as polymer support layer for transfer of graphene synthesized by chemical vapor deposition (CVD). This combination primarily improves the flexibility of the polystyrene to prevent cracking during the transfer process. In addition, the polymer removal solvent can easily penetrate between the softener molecules, so that the polymer film can be easily dissolved after transfer of graphene, thereby leaving no residue. This facile method can be used freely for the large-scale transfer of 2D materials. [ABSTRACT FROM AUTHOR]

Highlights from the article: Chemical Vapor Deposition: An Eco-Friendly, CMOS-Compatible Transfer Process for Large-Scale CVD-Graphene (Adv. In article number 1900084, Ji-Yun Moon, Dongmok Whang, Hak Ki Yu, Jae-Hyun Lee, and co-workers demonstrate a clean transfer method for large scale chemical vapor deposition (CVD) graphene using MoO SB 3 sb as a protective film, which can be dissolved in pure DI water, easily and completely. The authors believe that this approach provides new solutions to overcome the limitations of the conventional transfer methods for CVD graphene and pave the way for future transfer method for CMOS manufacturing processes.

Since the first realization of graphene synthesis through the chemical vapor deposition (CVD) method in 2009, CVD‐graphene is regarded as a key material in the future electronics industry, and one that requires high standard characteristics. However, because graphene itself is not a semiconductor, therefore it does not have a bandgap, a promising application is considered to integrate its use with semiconductors, rather than completely replace Si or Ge. Although numerous methods for a clean and uniform graphene transfer process are developed, graphene growth and transfer methods that are applicable to current mainstream Si‐based complementary metal‐oxide‐semiconductor (CMOS) manufacturing processes are not yet introduced. This study implements an eco‐friendly and CMOS‐compatible graphene transfer process through water‐soluble inorganic MoO3 film as a supporting layer. Since the monolayer graphene is grown on hydrogen‐terminated semiconductor Ge surface, the MoO3 thin film coated graphene is easily delaminated from the Ge substrate. The separated graphene could be transferred to arbitrary substrate without a chemical wet etching process, and the remaining Ge substrate could be employed for about 50 times multiple reuse for the growth of graphene, without degradation of the crystallinity of the graphene. [ABSTRACT FROM AUTHOR]

The oblique angle deposition of Ag with different deposition rates and substrates was studied for surface-enhanced Raman spectroscopy (SERS) efficiency. The deposition rate for the Ag substrate with maximum SERS efficiency was optimized to 2.4 Å/s. We also analyzed the morphology of Ag nanorods deposited at the same rate on various substrates and compared their SERS intensities. Ag deposited on SiO2, sapphire, and tungsten showed straight nanorods shape and showed relatively high SERS efficiency. However, Ag deposited on graphene or plasma-treated SiO2 substrate was slightly or more aggregated (due to high surface energy) and showed low SERS efficiency. [ABSTRACT FROM AUTHOR]

The effect of graphene coating on the growth of grains on bulk copper film was studied. When methane gas is catalytically decomposed on the surface of copper, and a carbon–copper solid solution is formed at high temperature, precipitated carbon on the copper surface forms graphene during rapid cooling through strong sp2 covalent bonding. The graphene layer can prevent the growth of grains by suppressing the diffusion of copper atoms on the surface, even after continuous heat treatment at high temperatures. The actual size of the copper grains was analyzed in terms of repetitive high-temperature heat treatment processes, and the grain growth process was simulated by using thermodynamic data, such as surface migration energy and the binding energy between copper and carbon. In general, transition metals can induce graphene growth on surfaces because they easily form carbon solid solutions at high temperatures. It is expected that the process of graphene growth will be able to suppress grain growth in transition metals used at high temperatures and could be applied to materials that are prone to thermal fatigue issues such as creep. [ABSTRACT FROM AUTHOR]

In this study, a thermal release tape-supported Ru on graphene film (Ru/G/TRT) was proposed as a catalyst for the dehydrogenation of sodium borohydride (NaBH 4). A 200-nm-thick Ru film deposited on the C-plane of sapphire by physical vapor deposition was used for the synthesis of graphene via chemical vapor deposition. X-ray diffraction analysis revealed the polycrystalline nature of the thin films. Furthermore, Raman spectroscopy and scanning electron microscopy revealed the successful synthesis of graphene. Thus, the prepared Ru graphene (Ru/G) structure was covered with TRT, while simultaneous etching resulted in a Ru/G/TRT structure. The water displacement method was employed to evaluate the catalytic performance of the proposed structure, which was found to highly improve with respect to the etched Ru/G structure, with maintenance of stability after repeated use. Finally, surface study by X-ray photoelectron spectroscopy revealed the presence of metallic Ru on both Ru/G and Ru/G/TRT surfaces after repeated use, which further confirmed the stability of the structure. • Thermal release tape supported graphene/Ru hybrid film for sodium borohydride (NaBH 4) hydrogenation. • Partially etched Ru surface are well supported by thin carbon graphene and thermal release tape structures. • Highly improved catalytic performance with maintenance of stability after repeated use. [ABSTRACT FROM AUTHOR]

H 2 sensors play a crucial role in the development of hydrogen (H 2) energy and safety monitoring. Therefore, efficiently and rapidly detecting low concentrations of H 2 is a fundamental challenge that needs to be addressed in the field of H 2 sensors. In this study, we present a highly sensitive H 2 gas sensor based on Pd-nanoparticles (NPs)-decorated transfer-free three-dimensional (3D) graphene. 3D graphene provides an increased surface area for enhanced gas adsorption and reaction kinetics. The integration of PdNPs improved the electron transport properties, resulting in a higher sensitivity. The PdNP-decorated 3D graphene sensor exhibited a remarkable gas response of 41.9% under 3% H 2 exposure. The transfer-free synthesis process ensures the excellent conductivity of 3D graphene to further enhance its overall sensing performance. These discoveries propel current gas-sensing technologies forward and introduce fresh opportunities for the development of dependable sensors that can effectively enhance industrial safety and public security. • Transfer-free synthesis of 3D graphene on SiO 2 /Si substrate. • Thermal evaporation of Pd nanoparticles onto 3D graphene for H 2 sensors. • High-responsivity H 2 sensing behavior of PdNPs/3D graphene H 2 sensors. [ABSTRACT FROM AUTHOR]

Abstract Chemical vapor deposition (CVD) is one of the best ways to scalably grow low cost, high quality graphene on metal substrates; unfortunately, it not ideal for producing graphene on dielectric substrates. Here, we demontrate production of a high quality graphene layer on Sapphire using CVD with a copper catalyst. The catalyst consists of a thin copper film grown epitaxially on α - Al 2 O 3 (0001). After CVD growth of Graphene, the copper can be removed by simple evaporation in the presence of a carbon source (C 2 H 4). We characterized the resulting graphene layer using Raman spectroscopy, atomic force microscopy (AFM), optical transmission and helium atom scattering (HAS). The sample exhibited a reduced Raman D peak and an excellent 2D to G ratio. AFM and HAS show large graphene domains over a macroscopic region. We measured > 86 % transparency over the visible spectrum. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

The thermal transport growth of various metal oxide (MO x ) nanostructures using graphene as a catalytic layer was studied. Graphene was synthesized by Cu-catalyzed chemical vapor deposition and transferred onto a SiO 2 -covered Si substrate using bubble transfer methods. Due to the catalytic activity of the atomic-thick carbon layer, control of the position of the MO x nanostructures as well as the growth parameters, such as nucleation density and growth rate, could be achieved. The position-selective and density-controlled MO x nanostructures were evaluated for hydrogen gas sensor applications, where different responses were obtained with hydrogen molecules. [ABSTRACT FROM AUTHOR]

Growth of ZnO thin film on conventional Si (100) substrate using atomically thin graphene as a buffer layer has been studied. The graphene buffer layer was synthesized by Cu-catalyzed chemical vapor deposition method and transferred on Si (100) using well-established polymer coating and Cu etching techniques. The ZnO film with (0002) preferred orientation was developed on graphene buffered Si (100) compared to ZnO film grown on Si (100) directly, which showed random orientation distribution. The graphene layer acts as not only lattice matching with ZnO but also diffusion barrier between ZnO and Si substrate, resulting in high electron mobility and photoluminescence intensity of ZnO film. [ABSTRACT FROM AUTHOR]