Abstract : Van der Waals heterojunctions composed of graphene and transition metal dichalcogenides have gain much attention because of the possibility to control and tailor band structure, promising applications in two-dimensional optoelectronics and electronics. In this report, we characterized the van der Waals heterojunction MoSe$_2$/few-layer graphene with a high-quality interface using cutting-edge surface techniques scaling from atomic to microscopic range. These surface analyses gave us a complete picture of the atomic structure and electronic properties of the heterojunction. In particular, we found two important results: the commensurability between the MoSe$_2$ and few-layer graphene lattices and a band-gap opening in the few-layer graphene. The band gap is as large as 250 meV, and we ascribed it to an interface charge transfer that results in an electronic depletion in the few-layer graphene. This conclusion is well supported by electron spectroscopy data and density functional theory calculations. The commensurability between the MoSe$_2$ and graphene lattices as well as the band-gap opening clearly show that the interlayer interaction goes beyond the simple van der Waals interaction. Hence, stacking two-dimensional materials in van der Waals heterojunctions enables us to tailor the atomic and electronic properties of individual layers. It also permits the introduction of a band gap in few-layer graphene by interface charge transfer.
https://hal.archives-ouvertes.fr/hal-01847258
Contributeur : Dominique Girard
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Soumis le : lundi 23 juillet 2018 - 14:00:20
Dernière modification le : mercredi 25 juillet 2018 - 01:20:18
Minh Tuan Dau, Maxime Gay, Daniela Di Felice, Céline Vergnaud, Alain Marty, et al.. Beyond van der Waals Interaction: The Case of MoSe$_2$ Epitaxially Grown on Few-Layer Graphene. ACS Nano, American Chemical Society, 2018, 12, pp.2319 - 2331. 〈10.1021/acsnano.7b07446〉. 〈hal-01847258〉
