Concentric dopant segregation in CVD-grown N-doped graphene single crystals

Lin, J, Tay, R, Li, H, Jing, L, Tsang, S, Bolker, A, Saguy, C and Teo, H 2018, 'Concentric dopant segregation in CVD-grown N-doped graphene single crystals', Applied Surface Science, vol. 454, pp. 121-129.


Document type: Journal Article
Collection: Journal Articles

Title Concentric dopant segregation in CVD-grown N-doped graphene single crystals
Author(s) Lin, J
Tay, R
Li, H
Jing, L
Tsang, S
Bolker, A
Saguy, C
Teo, H
Year 2018
Journal name Applied Surface Science
Volume number 454
Start page 121
End page 129
Total pages 9
Publisher Elsevier
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.
Subject Surfaces and Structural Properties of Condensed Matter
Keyword(s) Chemical vapor deposition
Dopant segregation
Monolayer
Nitrogen-doped graphene
Raman spectroscopy
Single crystal
DOI - identifier 10.1016/j.apsusc.2018.05.132
Copyright notice © 2018 Elsevier Ltd. All rights reserved.
ISSN 0169-4332
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