Regensburg 2022 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 18: Poster Monday: 2D Materials 1

O 18.8: Poster

Montag, 5. September 2022, 18:00–20:00, P4

Quantum well states in Bi(110) islands grown on epitaxial graphene — •Chitran Ghosal and Christoph Tegenkamp — Institut für Physik, TU Chemnitz

The semimetal Bi attracts a lot of interest because of its unique electronic properties such as a low carrier concentrations and large carrier mobilities coming along with mesoscopic Fermi wavelength giving rise to robust quantum confinement effects and spin polarized states in thin films [1]. In this work we studied the growth of Bi on n-type doped monolayer graphene (MLG) on SiC(0001) by means of STS and STM. While for low coverages Bi(110) islands are formed Bi(111) structures were found for higher coverages. This allotropic transition occurs at 10 monolayers (3.3nm) and is significantly larger than the critical coverage reported for Bi on Si(111) [2]. In contrast to Bi/MLG, the deposition of Bi on HOPG results in the formation of islands with an odd number of layers. These differences were attributed to different substrate screening effects. Irrespective of the interface, Bi seems to grow rather in a relaxed bilayers fashion, i.e. supporting the formation of black phosphorous structures [2]. Spectroscopy performed on islands of different heights revealed a large gap opening (750 meV) at the center of 4 ML islands. In addition, we found signatures of edge states, which might refer to a non-trivial topology within these QWS-stabilized nanostructures.

[1] T. Hirahara et al. Phys. Rev. B 75, 035422 (2007); [2] T. Nagao et al. Phys. Rev. Lett. 93, 105501 (2004).