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O: Fachverband Oberflächenphysik

O 78: Poster Session VI: 2D Materials: Electronic structure, excitations, etc. II

O 78.9: Poster

Mittwoch, 3. März 2021, 13:30–15:30, P

Band structure and image potential states of hBN/Cu(111) — •Jan Beckord, Matthias Hengsberger, and Jürg Osterwalder — Physik-Institut, Universität Zürich, Schweiz

We present a study on the band structure and the image potential states of a hexagonal boron nitride (hBN) monolayer on the Cu(111) surface. The orientation of the bare copper surface was measured by XPD and ARPES. The hBN layer was then grown by chemical vapour deposition from borazine. XPS spectra confirm the presence of a full monolayer with the correct stoichiometry, and ARPES band structure measurements with He IIa radiation along the high symmetry directions ΓK and ΓM are in excellent agreement with literature values for other metal substrates. The work function is significantly reduced from 4.9 eV to 4.1 eV, which agrees with the reported work function in valleys of the corrugated surface measured by STM. We then measured the unoccupied electronic states with two-photon photoelectron spectroscopy on the bare copper as well as on the hBN covered surface. Varying the photon energy allowed us to separate the first two image potential states n=1 at 0.83 eV and n=2 at 0.16 eV below the vacuum level from the Shockley surface state at a binding energy of 0.27 eV. The valence band maximum in normal emission direction appeared at a binding energy of 2.21 eV.