Regensburg 2022 – scientific programme

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O: Fachverband Oberflächenphysik

O 41: Graphene: Growth, Substrate Interaction, Intercalation, and Doping

O 41.7: Talk

Wednesday, September 7, 2022, 12:00–12:15, S052

Surface Transport Properties of Pb- and Sn-intercalated Graphene — •M. Gruschwitz, C. Ghosal, Z. Mamiyev, J. Koch, S. Wolff, T. Seyller, and C. Tegenkamp — Institut für Physik, Technische Universität Chemnitz, Chemnitz, Germany

Intercalation experiments on epitaxial graphene are attracting a lot of attention at present as a tool to boost further the electronic properties of 2D graphene. In this work we studied the intercalation of Pb using buffer layers on 6H-SiC(0001). Recent DFT calculations suggest Pb atoms to act as electron donors thus allowing the doping level of the quasi-freestanding graphene layer to be tuned by the amount of intercalated material [1].

In this work we present results about the large-area intercalation of Pb and Sn, investigated by means of electron diffraction, scanning tunneling microscopy, photoelectron spectroscopy and in-situ surface transport. The intercalation of Pb and Sn results in formation of almost charge neutral graphene. In case of Pb, the intercalated layer consists of 2 ML and shows a strong structural corrugation. The epitaxial heterostructure provides an extremely high conductivity of σ=100 mS/. However, below 70 K we found a metal-insulator transition which we assign to the formation of minigaps in epitaxial graphene, possibly induced by a static distortion of graphene following the corrugation of the interface layer [2]. Sn intercalation does not cause such a transition while yielding a conductivity of σ=2.5 mS/.

[1] J. Wang et al., PRB 103, 085403 (2021); [2] M. Gruschwitz et al., Materials 14, 7706 (2021)