Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 94: 2D Materials V: Novel Systems

O 94.6: Vortrag

Freitag, 5. April 2019, 11:45–12:00, H9

Electrostatic Screening at the Surface of Black Phosphorus — •Brian Kiraly, Elze Knol, Daniel Wegner, and Alexander Khajetoorians — Radboud University, The Netherlands

Under applied electric fields, black phosphorus theoretically demonstrates an electronic phase transition from insulating to metallic [1]. Using chemical dopants with very small electronegativity, bulk black phosphorus can be doped into such a transition [2]; however, atomic-scale insight into the local screening and surface charge inhomogeneity is missing. Here, we probe the spatial distribution of deposited potassium adatoms on the surface of black phosphorus, with low temperature scanning tunneling microscopy, as a function of temperature and coverage. We relate the spatial distribution of adatoms to the underlying screened electrostatic potential, utilizing thermodynamic formalism, and extract the 2D vector mean potential. The data reveal the presence of extremely anisotropic, long-range interactions with strong oscillations along the zig-zag direction. The data is discussed within the context of screened Coulomb interactions, free carrier mediated Friedel-like oscillations, and strong electrostatic confinement.

[1] Q. Liu, X. Zhang, L. B. Abdalla, A. Fazzio, A. Zunger. Nano Lett. 15 (2), 2015. [2] J. Kim, S. S. Baik, S. H. Ryu, Y. Sohn, S. Park, B. G. Park, J. Denlinger, Y. Yi, H. J. Choi, K. S. Kim. Science 349 (6249), 2015.