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Direct growth of mm-size twisted bilayer graphene by plasma-enhanced chemical vapor deposition

Chen, Yen-Chun and Lin, Wei-Hsiang and Tseng, Wei-Shiuan and Chen, Chien-Chang and Rossman, George R. and Chen, Chii-Dong and Wu, Yu-Shu and Yeh, Nai-Chang (2020) Direct growth of mm-size twisted bilayer graphene by plasma-enhanced chemical vapor deposition. Carbon, 156 . pp. 212-224. ISSN 0008-6223. doi:10.1016/j.carbon.2019.09.052.

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Plasma enhanced chemical vapor deposition (PECVD) techniques have been shown to be an efficient method to achieve single-step synthesis of high-quality monolayer graphene (MLG) without the need of active heating. Here we report PECVD-growth of single-crystalline hexagonal bilayer graphene (BLG) flakes and mm-size BLG films with the interlayer twist angle controlled by the growth parameters. The twist angle has been determined by three experimental approaches, including direct measurement of the relative orientation of crystalline edges between two stacked monolayers by scanning electron microscopy, analysis of the twist angle-dependent Raman spectral characteristics, and measurement of the Moiré period with scanning tunneling microscopy. In mm-sized twisted BLG (tBLG) films, the average twist angle can be controlled from 0° to approximately 20°, and the angular spread for a given growth condition can be limited to < 7°. Different work functions between MLG and BLG have been verified by the Kelvin probe force microscopy and ultraviolet photoelectron spectroscopy. Electrical measurements of back-gated field-effect-transistor devices based on small-angle tBLG samples revealed high-quality electric characteristics at 300 K and insulating temperature dependence down to 100 K. This controlled PECVD-growth of tBLG thus provides an efficient approach to investigate the effect of varying Moiré potentials on tBLG.

Item Type:Article
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URLURL TypeDescription Paper
Lin, Wei-Hsiang0000-0003-0037-1277
Rossman, George R.0000-0002-4571-6884
Yeh, Nai-Chang0000-0002-1826-419X
Additional Information:© 2019 Elsevier Ltd. Received 3 July 2019, Revised 2 September 2019, Accepted 19 September 2019, Available online 21 September 2019. The work at Caltech was jointly supported by the National Science Foundation under the Institute for Quantum Information and Matter (IQIM), Award #1733907, and the Army Research Office under the Multi-University Research Initiative (MURI) program, Award #W911NF-16-1-0472. Y.-C. Chen, C.-D. Chen and Y.-S. Wu gratefully acknowledge the Dragon-Gate Program (MoST 106-2911-I-007-520) under the Ministry of Science and Technology (MoST) in Taiwan (R.O·C.) for supporting their visit to Caltech and the collaborative research. We thank Prof. Io-Chun Hoi, Dr. Ping-Yi Wen, Dr. Po-Hsun Ho, Dr. Chin-Pin Lee and master student Yen-Tsia Wang for their assistance with the low-temperature electrical transport measurements and the wire-bonding techniques; Prof. Mei-Ying Chou for her support during the execution of Dragon-Gate Project; Prof. Po-Wen Chiu, Dr. Chao-Hui Yeh, and PhD student Zheng-Yong Liang for their experimental guidance of Y.-C. Chen in graphene growth and fabrication of devices based on 2D materials; and Caltech PhD student Chen-Chih Hsu for useful discussion about PECVD growth techniques. Author contributions: First author Y.-C. Chen investigated the entire PECVD growth procedures for the synthesis of BLG, carried out Raman spectroscopic characterization, SEM surface characterization, two-terminal back-gated devices fabrication, and related electrical measurements. W.-H Lin carried out KPFM measurements and also had in-depth discussions with Y.-C. Chen about PECVD-growth of MLG and BLG. W.-S. Tseng performed the work function measurements using UPS and also mentored Y.-C. Chen the operation of the PECVD system. C.-C. Chen carried out STM measurements and related analyses. G. R. Rossman provided the Raman spectroscopic measurement facilities that are critically important for this work. C.-D. Chen and Y.-S. Wu engaged in active discussions about the experimental and theoretical development of this project. N.-C. Yeh as the principal investigator at Caltech coordinated the research project, data analysis, and wrote the manuscript together with Y.-C. Chen.
Group:Institute for Quantum Information and Matter
Funding AgencyGrant Number
Institute for Quantum Information and Matter (IQIM)1733907
Army Research Office (ARO)W911NF-16-1-0472
Ministry of Science and Technology (Taipei)106-2911-I-007-520
Record Number:CaltechAUTHORS:20190923-100220892
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Official Citation:Yen-Chun Chen, Wei-Hsiang Lin, Wei-Shiuan Tseng, Chien-Chang Chen, George.R. Rossman, Chii-Dong Chen, Yu-Shu Wu, Nai-Chang Yeh, Direct growth of mm-size twisted bilayer graphene by plasma-enhanced chemical vapor deposition, Carbon, Volume 156, 2020, Pages 212-224, ISSN 0008-6223, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:98792
Deposited By: Tony Diaz
Deposited On:23 Sep 2019 17:10
Last Modified:16 Nov 2021 17:41

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