Article
Chemistry, Physical
Shengxue Zhou, Lina Liu, Shuang Cui, Xiaofan Ping, Dake Hu, Liying Jiao
Summary: A new method using chemical vapor deposition (CVD) with K2WS4 as growth precursor was developed for the growth of large and high-quality WS(2) monolayers, achieving a fast growth rate and high electrical performance. The obtained WS(2) flakes were 2D single crystals with low defect density, demonstrating the potential for producing high quality 2D semiconductors for future nanoelectronics.
Article
Chemistry, Physical
Ming Huang, Bangwei Deng, Fan Dong, Lili Zhang, Zheye Zhang, Peng Chen
Summary: This article provides a comprehensive and comparative review on the selection and preparation of various single-crystal substrates for CVD growth of SCG under different conditions. The growth mechanisms, current challenges, and future development and perspectives are discussed in detail.
Review
Physics, Applied
Rajesh, Zhaoli Gao, A. T. Charlie Johnson, Nidhi Puri, Ashok Mulchandani, D. K. Aswal
Summary: Chemical species adsorbed on the surface of graphene can alter the concentration of charge carriers, affecting the material's electronic properties and enabling graphene-based sensors to detect a wide range of biomolecules, chemicals, and gas/vapors. Chemical vapor deposition grown graphene has been proven to be the most prominent route to large-scale device production. However, a comprehensive review on scalable, macro-sized, chemical vapor-deposited graphene-based field-effect transistor sensors is still lacking.
APPLIED PHYSICS REVIEWS
(2021)
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
Zhaolong Chen, Chunyu Xie, Wendong Wang, Jinpei Zhao, Bingyao Liu, Jingyuan Shan, Xueyan Wang, Min Hong, Li Lin, Li Huang, Xiao Lin, Shenyuan Yang, Xuan Gao, Yanfeng Zhang, Peng Gao, Kostya S. Novoselov, Jingyu Sun, Zhongfan Liu
Summary: This study demonstrates a method for direct growth of highly oriented monolayer graphene films on sapphire wafers by using an electromagnetic induction heating CVD at elevated temperature. The obtained graphene film shows significantly improved carrier mobility and reduced sheet resistance, which compare favorably with other growth methods.
Article
Chemistry, Multidisciplinary
Shan Liu, Baizhe He, Wei Yang, Xiahong Zhou, Xudong Xue, Mengya Liu, Yao Zhao, Xinhe Wang, Jia Si, Fuyi Wang, Zhiyong Zhang, Lianmao Peng, Gui Yu
Summary: This study reports the use of local space-confined chemical vapor deposition growth technique to efficiently produce high-quality single-crystal twisted bilayer graphene (TBG) with twist angles ranging from 0 to 30 degrees on liquid copper substrates. The clean surface, high crystallinity, thermal stability, stacking structure, growth mechanism, and electrical transport properties of the as-grown TBG are investigated. The results show that the liquid copper surface promotes the growth of TBG with twist-angle-dependent electronic properties.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Bixuan Li, Juntian Wei, Chunqiao Jin, Kunpeng Si, Lingjia Meng, Xingguo Wang, Yangyu Jia, Qianqian He, Peng Zhang, Jinliang Wang, Yongji Gong
Summary: In this study, an intercalation strategy using organic molecules was developed to fabricate high-quality and diverse twisted bilayer graphene (tBLG). By weakening the interlayer interaction and inducing slide or rotation of the topmost graphene layer, the proportion of tBLGs in the resulting dtBLG reached up to 84.4% for twist angles ranging from 0 degrees to 30 degrees, surpassing previous methods. The twist angle distribution was found to be non-uniform, concentrating in the ranges of 0-10 degrees and 20-30 degrees. This facile and rapid intercalation-based methodology provides a practical solution for studying angle-dependent physics and advancing the utilization of twisted two-dimensional materials.
Article
Chemistry, Multidisciplinary
Ruinan Wu, Yueguo Hu, Peisen Li, Junping Peng, Jiafei Hu, Ming Yang, Dixiang Chen, Yanrui Guo, Qi Zhang, Xiangnan Xie, Jiayu Dai, Weicheng Qiu, Guang Wang, Mengchun Pan
Summary: This study focuses on improving the tunnel magnetoresistance effect in magnetic tunnel junctions by growing high-quality graphene on Ni(111) substrates. Through APCVD, a high-quality graphene/Ni(111) heterostructure with an atomically sharp interface was successfully fabricated, providing a new approach for interface engineering in 2D spintronic applications.
Article
Chemistry, Multidisciplinary
Jie Li, Yan Zhang, Junrong Zhang, Junwei Chu, Liu Xie, Wenzhi Yu, Xinxin Zhao, Cheng Chen, Zhuo Dong, Luyi Huang, Liu Yang, Qiang Yu, Zeqian Ren, Junyong Wang, Yijun Xu, Kai Zhang
Summary: The controllable synthesis of quaternary 2D BiCuSeO nanosheets with excellent ambient stability and intrinsic p-type degeneracy has been achieved by chemical vapor deposition (CVD). These nanosheets can be used to fabricate high-performance tunnel field-effect transistors (TFETs) with adjustable carrier concentration and show potential for practical implementation.
ADVANCED MATERIALS
(2022)
Review
Chemistry, Multidisciplinary
Jingyuan Shan, Jingyu Sun, Zhongfan Liu
Summary: Growing graphene on sapphire substrates using CVD allows for fewer grain boundaries, larger grain sizes, and transfer-free properties. Sapphire has emerged as an ideal substrate for graphene growth due to its low cost, good mechanical strength, and stability under CVD conditions. Applications of graphene/sapphire hybrid materials are diverse and the synthesis of graphene over sapphire shows promise.
Article
Chemistry, Multidisciplinary
Wei Li, Ruixia Wu, Qiuqiu Li, Quanyang Tao, Muhammad Zeeshan Saeed, Xin Li, Si Wan, Rong Song, Dingyi Shen, Kejing Huang, Miaomiao Liu, Bailing Li, Bei Zhao, Jialing Liu, Yuan Liu, Bo Li, Jia Li, Xidong Duan
Summary: This study reports the synthesis of alpha-GeTe nanoplates on different substrates and the characterization of their structure and electrical properties. The results show that the alpha-GeTe nanoplates exhibit excellent conductivity and high breakdown current density. When used as van der Waals metal electrodes in WSe2 transistors, they significantly improve the device performance, including higher on-state current and electron mobility.
ADVANCED FUNCTIONAL MATERIALS
(2022)
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.
Review
Materials Science, Multidisciplinary
Baojun Sun, Jinbo Pang, Qilin Cheng, Shu Zhang, Yufen Li, Congcong Zhang, Dehui Sun, Bergoi Ibarlucea, Yang Li, Duo Chen, Huaimin Fan, Qingfang Han, Mengxin Chao, Hong Liu, Jingang Wang, Gianaurelio Cuniberti, Lin Han, Weijia Zhou
Summary: The discovery of graphene has opened up new platforms for physics, electronic engineering, and materials sciences. Among various synthesis approaches, chemical vapor deposition shows promise for wafer-scale growth. This article provides a comprehensive overview of wafer-scale graphene synthesis and its potential applications in electronics.
ADVANCED MATERIALS TECHNOLOGIES
(2021)
Article
Chemistry, Multidisciplinary
Yunqing Li, Myeonggi Choe, Sunghwan Jin, Da Luo, Pavel V. Bakharev, Won Kyung Seong, Feng Ding, Zonghoon Lee, Rodney S. Ruoff
Summary: The authors report the growth of micrometer-long single-crystal graphene ribbons with tapered or uniform width using silica particle seeds on single crystal Cu foils. The growth mechanism involves catalytic activation of ethylene and attachment of C atoms or species at the edges, as well as longitudinal growth driven by VLS mechanism.
Article
Physics, Applied
Pavel V. Fedotov, Elena D. Obraztsova
Summary: This study synthesized narrow graphene nanoribbons and investigated their photoluminescence properties. The results showed that these nanoribbons have a wide optical bandgap and exhibit bright photoluminescence in the infrared spectrum range.
APPLIED PHYSICS LETTERS
(2023)
Article
Engineering, Environmental
Rasel Das, Pablo Solis-Fernandez, Daniel Breite, Andrea Prager, Andriy Lotnyk, Agnes Schulze, Hiroki Ago
Summary: This study demonstrates a high-flux enabled non-functionalized hexagonal boron nitride membrane with excellent pollutant adsorption and membrane stability properties, as well as high removal efficiency for organic dyes in water.
CHEMICAL ENGINEERING JOURNAL
(2021)
Article
Chemistry, Physical
Dong Ding, Yuta Maeyoshi, Masaaki Kubota, Jungo Wakasugi, Koshin Takemoto, Kiyoshi Kanamura, Hidetoshi Abe
Summary: The study demonstrates a cost-effective synthesis approach of lithium-ion conducting glass ceramic/reduced graphene oxide composite, forming a sandwich-like structure that enhances the rate and cycle performances of the electrodes. The combination of LICGC and rGO provides ultrafast Li-ion and electron pathways, leading to improved rate capability and cyclability for the electrodes.
JOURNAL OF POWER SOURCES
(2021)
Article
Chemistry, Multidisciplinary
Sota Hirokawa, Hideaki Teshima, Pablo Solis-Fernandez, Hiroki Ago, Qin-Yi Li, Koji Takahashi
Summary: The nano-scale pinning of three-phase contact lines was experimentally investigated, revealing that metal nanoparticles and nanoflakes, rather than graphene surface inhomogeneity, caused the pinning of the gas-liquid interface. This phenomenon was attributed to repulsive forces and physical mechanisms involving nanoconfinement effects and hydration layers.
Article
Nanoscience & Nanotechnology
Pablo Solis-Fernandez, Hiroki Ago
Summary: In this work, the use of machine learning techniques for the automated classification of the Raman spectrum of twisted bilayer graphene (tBLG) into a selected range of twist angles is proposed. The ML classification is low computationally demanding and provides fast and accurate results with a high agreement with the manual labeling of the spectra.
ACS APPLIED NANO MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Yuji Araki, Pablo Solis-Fernandez, Yung-Chang Lin, Amane Motoyama, Kenji Kawahara, Mina Maruyama, Yanlin Gao, Rika Matsumoto, Kazu Suenaga, Susumu Okada, Hiroki Ago
Summary: This study investigates the twist angle dependence of intercalation of metal chlorides in bilayer graphene (BLG). It is found that high twist angle BLG is more favorable for intercalation due to weaker interlayer coupling. Scanning transmission electron microscope observations reveal the formation of various 2D structures through co-intercalation of AlCl3 and CuCl2 molecules. Moreover, high twist angle BLG exhibits lower sheet resistance before intercalation and intercalation further decreases the sheet resistance.
Article
Engineering, Electrical & Electronic
Satoru Fukamachi, Pablo Solis-Fernandez, Kenji Kawahara, Daichi Tanaka, Toru Otake, Yung-Chang Lin, Kazu Suenaga, Hiroki Ago
Summary: Centimetre-scale multilayer hBN can be synthesized on iron-nickel alloy foil and used as a substrate and surface-protecting layer in graphene field-effect transistors. An integrated electrochemical transfer and thermal treatment method enables the creation of high-performance graphene/hBN heterostacks. Graphene devices fabricated using conventional and scalable methods exhibit room-temperature carrier mobilities of up to around 10,000 cm(2) V-1 s(-1) when integrated with multilayers of hBN.
NATURE ELECTRONICS
(2023)
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
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
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
Microscopy
Sota Hirokawa, Hideaki Teshima, Pablo Solls-Fern, Hiroki Ago, Qin-Yi Li, Koji Takahashi
Summary: Despite the use of graphene liquid cells for atomic-resolution observation of liquid samples, no one has measured their three-dimensional shape and pressure simultaneously. In this study, we used an atomic force microscope to do so for cells with specific dimensions. We found an inverse relationship between the maximum pressure and the base radius, which can be explained by the adhesive force between graphene membranes. Additionally, the sample preparation procedure used in this experiment is reproducible and transferable to different substrates.
Article
Materials Science, Multidisciplinary
Hsiang-Lin Liu, Bergitta Dwi Annawati, Nguyen Tuan Hung, Desman Perdamaian Gulo, Pablo Solis-Fernandez, Kenji Kawahara, Hiroki Ago, Riichiro Saito
Summary: Using spectroscopy ellipsometry, we studied the optical absorption spectra of monolayer and bilayer graphene in the deep-ultraviolet region up to 6.42 eV and their temperature dependence. The spectra can be fitted by two BWF functions, each originating from the interference of excitonic and surface plasmon spectra. The narrower linewidth and higher peak intensity with increasing temperature can be explained by the shorter lifetime of the surface plasmon at higher temperatures.
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
Nanoscience & Nanotechnology
Hyun Goo Ji, Pablo Solis-Fernandez, Ufuk Erkilic, Hiroki Ago
Summary: Monolayers of TMD nanosheets with direct optical band gap exhibit exceptional optical properties, with unique physical properties such as interlayer excitons and superconductivity observed by controlling stacking orientation. By artificially stacking CVD-grown WS2, different stacking angles result in periodic changes in photoluminescence spectra and the observation of an additional low-energy PL peak in low-angle stacked bilayers. High optical quality of CVD-grown WS2 is crucial for observing intrinsic exciton dynamics without defect-induced localized excitons in TMD homobilayers.
ACS APPLIED NANO MATERIALS
(2021)
