Review
Chemistry, Multidisciplinary
Jinhong Du, Bo Tong, Shuangdeng Yuan, Nian Dai, Rui Liu, Dingdong Zhang, Hui-Ming Cheng, Wencai Ren
Summary: This article reviews the recent advances and significant development of CVD-grown graphene towards flexible optoelectronics. The challenges of improving optoelectronic properties, tuning work functions, and controlling interfaces are discussed, and the importance of fabricating large-area devices on flexible substrates is emphasized.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Multidisciplinary Sciences
Sergey G. Menabde, In-Ho Lee, Sanghyub Lee, Heonhak Ha, Jacob T. Heiden, Daehan Yoo, Teun-Teun Kim, Tony Low, Young Hee Lee, Sang-Hyun Oh, Min Seok Jang
Summary: The acoustic plasmon mode in a graphene-dielectric-metal structure shows strong light-matter interaction with relatively small propagation loss, allowing for real-space mapping under ambient conditions.
NATURE COMMUNICATIONS
(2021)
Article
Materials Science, Multidisciplinary
Binbin Ding, Lianbi Li, Lei Li, Tianming Wang, Changjun Zhu, Song Feng, Zebin Li, Jun Wang, Guoqing Zhang, Yuan Zang, Jichao Hu, Caijuan Xia
Summary: In this study, large-area monolayer MoS2 films were successfully grown on graphene using chemical vapor deposition (CVD) technique with the assistance of oxygen (O2). The introduction of O2 improved the growth environment of MoS2 domains and increased the grain size of MoS2. Spectroscopic results showed the deposition of a monolayer of MoS2 with high crystal quality on graphene. Effective charge transfer was observed in MoS2/graphene heterojunctions. The photodetector prepared by MoS2/graphene film exhibited good response to light. These findings indicate the great potential of MoS2/graphene heterojunctions for optoelectronic applications.
Article
Chemistry, Physical
Daniela Ion-Ebrasu, Radu Dorin Andrei, Stanica Enache, Simona Caprarescu, Constantin Catalin Negrila, Catalin Jianu, Adrian Enache, Iulian Boerasu, Elena Carcadea, Mihai Varlam, Bogdan Stefan Vasile, Jianwei Ren
Summary: In this study, nitrogen-doped and platinum functionalized three-dimensional graphene foam (3D-GrFoam) were prepared using hydrothermal treatment with different reducing agents. The nitrogen-doped sample showed higher electrochemical activity with 1.8 at % of N, while the platinum-functionalized sample exhibited a lower Tafel value, suggesting their potential for different electrochemical reaction mechanisms. Raman, infrared spectroscopy, and SEM analyses were conducted to understand the structure of the samples.
Article
Chemistry, Physical
Sara Fiori, Daniele Perilli, Mirco Panighel, Cinzia Cepek, Aldo Ugolotti, Alessandro Sala, Hongsheng Liu, Giovanni Comelli, Cristiana Di Valentin, Cristina Africh
Summary: High-quality nitrogen-doped graphene on nickel was prepared by utilizing both the catalytic properties of nickel and the solubility of nitrogen atoms. The experimental results demonstrated the growth of a flat, wide, continuous nitrogen-doped graphene layer, showing potential for various applications.
Review
Chemistry, Physical
Xing Xin, Jiamei Chen, Laipeng Ma, Teng Ma, Wei Xin, Haiyang Xu, Wencai Ren, Yichun Liu
Summary: Graphene, a single atomic layer of carbon, has great potential for various applications. Large-area graphene films grown by chemical vapor deposition are highly desirable but their properties are affected by grain boundaries. In the past decade, progress has been made in controlling grain sizes through modifying the growth processes. Strategies include controlling nucleation density, growth rate, and grain orientation.
Article
Chemistry, Multidisciplinary
Mitisha Surana, Ganesh Ananthakrishnan, Matthew M. Poss, Jad Jean Yaacoub, Kaihao Zhang, Tusher Ahmed, Nikhil Chandra Admal, Pascal Pochet, Harley T. Johnson, Sameh Tawfick
Summary: The study investigates the impact of interfacial interaction between 2D materials and the substrate on the electronic properties, and quantitatively analyzes the orientation-dependent facet topographies observed on graphene using electron backscatter diffraction and atomic force microscopy. Molecular simulations reveal that apart from anisotropic interfacial energy, graphene strain plays a critical role in forming the observed topographies. These findings are also applicable to other 2D/3D heterostructures.
Article
Chemistry, Physical
Xiucai Sun, Xiaoting Liu, Zhongti Sun, Xintong Zhang, Yuzhu Wu, Yeshu Zhu, Yuqing Song, Kaicheng Jia, Jincan Zhang, Luzhao Sun, Wan-Jian Yin, Zhongfan Liu
Summary: This study reveals the importance of vapor catalysis in superclean graphene growth through density functional theory calculations, an ideal gas model, and a designed experiment. The study finds that the vapor mainly consists of Cui clusters, which have a significant impact on graphene growth. DFT calculations show that Cu clusters exhibit strong capabilities for adsorption, dehydrogenation, and decomposition, providing a sufficient supply of active carbon atoms for rapid graphene growth. Experimental validation confirms that increasing the amount of Cu vapor improves the growth rate and surface cleanliness of graphene.
Article
Multidisciplinary Sciences
S. Karamat, U. Khalique, Arslan Usman, Asad Javaid, Ahmet Oral
Summary: Graphene was directly grown on TiO2 substrates using chemical vapor deposition. Characterization techniques including Raman spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy were employed to analyze the graphene-TiO2 samples. The results demonstrated the wide coverage of graphene on TiO2, but achieving uniform thickness throughout the substrate remains challenging.
ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING
(2022)
Article
Chemistry, Physical
Patrick Ryan Galligan, Yixin Xu, Tsz Wing Tang, Hongwei Liu, Mohsen Tamtaji, Yanguang Zhou, Zhengtang Luo
Summary: Hexagonal boron carbon nitride (hBCN) thin films with varying carbon doping levels were synthesized using chemical vapor deposition (CVD). The film with the highest carbon doping exhibited the highest thermal conductivity, surpassing that of hexagonal boron nitride (hBN). Molecular dynamics simulations revealed that aligning carbon to form graphene-like channels increased the high frequency phonon group velocities, leading to higher thermal conductivity. The aligned carbon channels were effective in overcoming phonon scattering, particularly in the LA mode. This research demonstrates an effective method of producing optimized hBCN thin films for thermal interface material applications, as a lower cost alternative to hBN.
Article
Materials Science, Multidisciplinary
Xin Zhou, ChuanHao Li, Ming Jiang, Tiwei Chen, Wenbo Tang, Yongjian Ma, Kun Xu, Feng Yang, Xiaodong Zhang, Li Zhang, Xinping Zhang, Zhongming Zeng, BaoShun Zhang
Summary: Large wafer-level hexagonal boron nitride (h-BN) film was grown on sapphire using MOCVD in pulse epitaxy mode. Comprehensive material characterizations were performed, revealing that the h-BN film exhibited hexagonal crystal phase with sp2 B-N bond. Unintentionally doped carbon element was found in the h-BN film, and its content was positively correlated with the flow rate of Triethyl-borane (TEB). The phenomenon of two-dimensional interlayer Van der Waals (vdW) characteristics and self-separation of h-BN on sapphire was observed.
Article
Materials Science, Multidisciplinary
Vishal Saravade, Zahra Manzoor, Alexis Corda, Chuanle Zhou, Ian Ferguson, Na Lu
Summary: This study investigates the optical properties and process-structure-property relationships of Mn-doped zinc oxide grown using metal-organic chemical vapor deposition with varying Mn-doping concentration and growth conditions. The results show that Mn-doping can alter the bandgap and photoluminescence characteristics of ZnMnO.
ADVANCED OPTICAL MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
Rizwan Ur Rehman Sagar, Xu Zaiping, Javed Iqbal, Sajjad Ur Rehman, Hamad Ashraf, Chao Liu, Jinming Zeng, Tongxiang Liang
Summary: In this study, successful doping of neodymium in graphene foam was achieved using double-zone chemical vapor deposition at hollow sites. The doping resulted in an extremely large positive magnetoresistance, which decreased after the fabrication of neodymium composite at high temperature.
MATERIALS TODAY PHYSICS
(2021)
Article
Chemistry, Physical
Mohammed Saquib Khan, Deependra Jhankal, Preeti Shakya, Atul Kumar Sharma, Malay Kumar Banerjee, Kanupriya Sachdev
Summary: This article presents the synthesis of few-layer pristine graphene and nitrogen-doped Bernal graphene (CVDNG) through low-pressure chemical vapor deposition approach for flexible supercapacitors. Raman mapping and X-ray photoelectron spectroscopy were used to analyze the characteristic bands and statistical distribution of Bernal stacking in CVDNG, and the doping in graphene was confirmed. CVDNG symmetrical supercapacitor device showed enhanced areal capacitance, high energy density, excellent flexibility, and specific capacitance retention after 10,000 charge-discharge cycles.
Article
Materials Science, Multidisciplinary
Salvatore Ethan Panasci, Ioannis Deretzis, Emanuela Schiliro, Antonino La Magna, Fabrizio Roccaforte, Antal Koos, Bela Pecz, Simonpietro Agnello, Marco Cannas, Filippo Giannazzo
Summary: The interface structure and electronic properties of monolayer MoS2 domains grown by chemical vapor deposition on 4H-SiC(0001) are investigated. The domains exhibit high crystalline quality and are epitaxially oriented on the basal plane. The presence of a van der Waals gap between MoS2 and SiC is observed. The calculations show different levels of refinement in the MoS2/4H-SiC(0001) system which result in different bonding and doping behaviors.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2023)
Article
Physics, Applied
Koji Takahara, Satoru Suzuki
Summary: The study shows that micro- and nanobubbles can be formed in situ in a conventional scanning electron microscope at low dose ratios, with lifetimes of at least three days. The observations suggest that pressure in the liquid cell is an important factor for bubble formation.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Nanoscience & Nanotechnology
Yao Yao, Ryota Negishi, Daisuke Takajo, Makoto Takamura, Yoshitaka Taniyasu, Yoshihiro Kobayashi
Summary: Ethanol chemical vapor deposition was used to grow graphene overlayers on an epitaxial graphene/silicon carbide solid template at temperatures ranging from 900 to 1450 degrees C. Structural analysis revealed that graphene islands grown at 1300 degrees C exhibited a hexagonal twisted bilayer graphene structure as a single crystal. Additionally, circular graphene islands and moire patterns with different periods were observed at higher growth temperatures, indicating the presence of multiple graphene domains with different twist angles. Overall, the growth of graphene overlayers on epitaxial graphene/SiC at 1300 degrees C proved to be an effective method for synthesizing high crystalline twisted few-layer graphene.
Article
Spectroscopy
Satoru Suzuki, Kento Takenaka, Koji Takahara, Hirosuke Sumida
Summary: Charging effect of insulating samples is a major problem in photoemission spectroscopy. The charging of the samples can be compensated by introducing nitrogen gas under near-ambient pressure. The distance between the sample surface and the aperture cone of the electron energy analyzer strongly affects the pressure required for compensation.
JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA
(2022)
Article
Nanoscience & Nanotechnology
Koji Takahara, Satoru Suzuki
Summary: Surface micro-and nanobubbles were formed in situ using a conventional scanning electron microscope by radiolysis of water, and their shapes and contact angles were measured and analyzed.
E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY
(2022)
Article
Physics, Applied
Makoto Takamura, Kenji Watanabe, Takashi Taniguchi, Yoshitaka Taniyasu
Summary: By using scattering-type scanning near-field optical microscopy, we studied the infrared spectra and imaging of hexagonal boron nitride at the nanoscale, revealing the significant influence of the number of layers and boundaries on the infrared amplitude changes.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Physics, Applied
Yoshiaki Sekine, Katsuya Oguri, Hiroki Hibino, Hiroyuki Kageshima, Yoshitaka Taniyasu
Summary: An array of embedded graphene ribbons, connected to a buffer layer, can be grown on 4H-SiC(0001). The polarization dependence of the Raman D peak intensity at the armchair edge of the ribbon is similar to that of non-connected graphene armchair edges. The polarization dependence suggests that electrons and holes in the embedded graphene are scattered back at the boundary of the embedded graphene ribbon and buffer layer.
APPLIED PHYSICS EXPRESS
(2023)
Article
Materials Science, Multidisciplinary
Hiroki Hibino, Hiroyuki Kageshima
Summary: We investigate the structural changes in Si islands deposited on epitaxial few-layer graphene on SiC(0001) at room temperature during subsequent annealing. Annealing causes the movement of Si islands on thick epitaxial graphene and leaves behind monolayer-deep trenches. In contrast, Si islands do not form trenches on monolayer graphene, but instead intercalate to form quasifreestanding bilayer graphene. The termination of island motion results in SiC islands. Si islands are carbonized into SiC islands during annealing by incorporating carbon atoms from graphene, leading to the etching of graphene. The carbonization reaction of Si is the driving force behind the motion of Si islands.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Multidisciplinary Sciences
Kaito Fujitani, Kento Takenaka, Koji Takahara, Hirosuke Sumida, Akinobu Yamaguchi, Yuichi Utsumi, Satoru Suzuki
Summary: We studied the mechanism of polytetrafluoroethylene (PTFE) chain scission using in situ hard X-ray photoelectron spectroscopy. The C-C bonds in the main chain and C-F bonds in the side chains were broken, resulting in F desorption from the PTFE surface. Recombination of broken C-C bonds and detached F led to the formation of CF3. The presence of thermal assistance at 230°C enhanced the formation of CF3 via recombination reactions. These findings have implications for the use of X-ray-irradiated fluorine resins and PTFE in space-based environments.
Article
Nanoscience & Nanotechnology
Hiroyuki Kageshima, Shengnan Wang, Hiroki Hibino
Summary: The origin of growth direction difference in graphene/hexagonal boron nitride (hBN) heterostructures during chemical vapor deposition (CVD) is theoretically studied. The study focuses on the energy gain with H termination of the bare hBN N edge on the Cu(111) surface compared to the bare graphene edge. The results indicate that the van der Waals correction method greatly affects the differences observed, and the most reliable method supports the speculation that the edge termination of existing islands automatically changes depending on whether it is graphene or hBN.
E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Kento Takenaka, Koji Takahara, Tomoki Eguchi, Hirosuke Sumida, Satoru Suzuki
Summary: This study systematically investigated the gas pressure dependence of photoelectron intensity in the range of 0.3 to 5 mm. The experimental results were explained by introducing a constant do in the Beer-Lambert law. Fluid dynamics simulation indicated that the long pumping path contributed to the large do value.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B
(2023)
Article
Chemistry, Physical
Kaito Fujitani, Yuichi Utsumi, Akinobu Yamaguchi, Hirosuke Sumida, Satoru Suzuki
Summary: The chemical composition of PTFE under bending stress was investigated using hard X-ray photoelectron spectroscopy and soft X-ray absorption spectroscopy. The breaking of C-F bonds in side chains and the observation of C-C bonds in the main chain were observed only on the surface under bending stress. The breaking of C-F bonds was found to be dependent on the tensile strain caused by bending.
APPLIED SURFACE SCIENCE
(2023)
Article
Chemistry, Physical
Fumihiko Maeda, Makoto Takamura, Hiroki Hibino
Summary: By using core-level photoelectron spectroscopy, the surface of SiC(0001)-6 root 3 x 6 root 3R30 degrees (buffer layer surface) formed on n-type and semi-insulating substrates was studied. The adsorption of hydrocarbons and chemical bonding of oxygen atoms to the carbon atoms in the buffer layer were observed when the surface was exposed to air after buffer layer formation. However, annealing in ultra-high vacuum and an ethylene ambient resulted in the removal of these impurities and a clean buffer layer surface was obtained. The band bending of the buffer layer on the n-type and semi-insulating substrates was estimated through the peak position of Si 2p.
Article
Chemistry, Multidisciplinary
Hsin Yi, Pablo Solis-Fernandez, Hiroki Hibino, Hiroki Ago
Summary: Hexagonal boron nitride (hBN) is an ideal substrate for two-dimensional materials, and when combined with group IV materials like tin (Sn), it exhibits unique behaviors such as the formation of triangular nanoplates and nanotrenches on the hBN surface. The structural changes of the nanotrenches can be induced by annealing without supplying Sn vapor.
NANOSCALE ADVANCES
(2022)
Article
Materials Science, Multidisciplinary
Keiju Sato, Naoki Hayashi, Takahiro Ito, Noriyuki Masago, Makoto Takamura, Mitsuru Morimoto, Takuji Maekawa, Doyoon Lee, Kuan Qiao, Jeehwan Kim, Keisuke Nakagahara, Katsunori Wakabayashi, Hiroki Hibino, Wataru Norimatsu
Summary: Researchers fabricated twisted bilayer graphene samples with an area exceeding 3 x 5 mm(2) and observed a flat band and large bandgap using angle-resolved photoemission spectroscopy, indicating the presence of superconductivity.
COMMUNICATIONS MATERIALS
(2021)
