Large local lattice expansion in graphene adlayers grown on copper

• Published in: Nature materials Vol. 17; no. 5; pp. 450 - 455
• Main Authors: Chen, Chaoyu, Avila, José, Arezki, Hakim, Nguyen, Van Luan, Shen, Jiahong, Mucha-Kruczyński, Marcin, Yao, Fei, Boutchich, Mohamed, Chen, Yue, Lee, Young Hee, Asensio, Maria C.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-05-2018; Nature Publishing Group
• Subjects: 119/118; 140/146; 639/301/357/918; 639/766/119/544; Biomaterials; Chemical vapor deposition; Chemistry and Materials Science; Condensed Matter Physics; Copper; Density functional theory; Energy; Engineering Sciences; Graphene; Lattice parameters; Materials Science; Mathematical analysis; Metal foils; Metastable phases; Nanotechnology; Optical and Electronic Materials; Spectrum analysis; Stiffness; Substrates
• ISSN: 1476-1122; 1476-4660
• DOI: 10.1038/s41563-018-0053-1

Variations of the lattice parameter can significantly change the properties of a material, and, in particular, its electronic behaviour. In the case of graphene, however, variations of the lattice constant with respect to graphite have been limited to less than 2.5% due to its well-established high in-plane stiffness. Here, through systematic electronic and lattice structure studies, we report regions where the lattice constant of graphene monolayers grown on copper by chemical vapour deposition increases up to ~7.5% of its relaxed value. Density functional theory calculations confirm that this expanded phase is energetically metastable and driven by the enhanced interaction between the substrate and the graphene adlayer. We also prove that this phase possesses distinctive chemical and electronic properties. The inherent phase complexity of graphene grown on copper foils revealed in this study may inspire the investigation of possible metastable phases in other seemingly simple heterostructure systems.
Angle-resolved photoemission spectroscopy with nanometre spatial resolution and low-energy electron microscopy/diffraction reveal that interaction with the Cu substrate can induce up to 7.5% lattice expansion in graphene adlayers.