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Title: Concentric dopant segregation in CVD-grown N-doped graphene single crystals
Authors: Lin, Jinjun
Tay, Roland Yingjie
Li, Hongling
Jing, Lin
Tsang, Siu Hon
Bolker, Asaf
Saguy, Cecile
Teo, Edwin Hang Tong
Keywords: Nitrogen-doped Graphene
DRNTU::Engineering::Electrical and electronic engineering
Chemical Vapor Deposition
Issue Date: 2018
Source: Lin, J., Tay, R. Y., Li, H., Jing, L., Tsang, S. H., Bolker, A., . . . Teo, E. H. T. (2018). Concentric dopant segregation in CVD-grown N-doped graphene single crystals. Applied Surface Science, 454, 121-129. doi:10.1016/j.apsusc.2018.05.132
Series/Report no.: Applied Surface Science
Abstract: Heteroatom doping in graphene leads to bandgap opening and tunable electronic, magnetic and optical properties, which are important for graphene-based electronics applications. In recent years, scalable growth of nitrogen-doped graphene (NG) by chemical vapor deposition (CVD) has been extensively studied because of its potential for practical applications. A phenomenon that occurs exclusively for CVD-grown NG films is the segregation of doping concentration. However, most studies to date are conducted using highly polycrystalline NG films comprising small grain sizes. It is still unknown whether dopant segregation occurs in single crystalline NG domains. Here, we used hexamethylenetetramine ((CH2)6N4) as a single-source solid precursor to grow hexagonal-shaped monolayer NG single crystals of ∼20 µm on Cu substrates. The NG single crystals exhibit discrete concentric hexagonal rings comprising N depleted regions as determined by Raman spectroscopy. Supported by scanning tunneling microscopy experiments, we propose that the segregation of N dopants is caused by a competing N attachment mechanism to either zigzag or Klein edges during growth; where the former should result in higher N concentration and the latter with lower N concentration. This work provides critical insights into the growth mechanism of CVD-grown NG and enables new opportunities to engineer the properties of graphene by fabrication of lateral heterostructures.
ISSN: 0169-4332
DOI: 10.1016/j.apsusc.2018.05.132
Rights: © 2018 Elsevier B.V. All rights reserved. This paper was published in Applied Surface Science and is made available with permission of Elsevier B.V.
Fulltext Permission: open
Fulltext Availability: With Fulltext
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