Hamburg 2001 – wissenschaftliches Programm
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O: Oberflächenphysik
O 13: Postersitzung (Adsorption auf Oberfl
ächen, Oberfl
ächenreaktionen, Elektronische Struktur, Epitaxie und Wachstum, Halbleiteroberfl
ächen und Grenzfl
ächen, Oxide und Isolatoren)
O 13.39: Poster
Montag, 26. März 2001, 19:00–22:00, Foyer zu B
Localized and delocalized valence states in a HfS2 monolayer on WSe2 — •C. Kreis1, S. Werth1, R. Adelung1, L. Kipp1, M. Skibowski1, D. Voß2, P. Krüger2, A. Mazur2, and J. Pollmann2 — 1Institut für Experimentelle und Angewandte Physik, Universität Kiel, D-24118 Kiel, Germany — 2Institut für Festkörpertheorie, Universität Münster, D-48149 Münster, Germany
Applying van der Waals epitaxy we have grown a semiconductor heterostructure consisting of the layered crystals HfS2 and WSe2. For one monolayer HfS2, i.e. three atomic layers, adsorbed on WSe2 the electronic interaction of the overlayer with the substrate across the interface is studied with angle–resolved photoelectron spectroscopy. Two different types of HfS2 valence states are investigated which exhibit complementary behavior. One is strongly localized in the HfS2 overlayer and yields an almost dispersionless band in k-space perpendicular to the layers. The other is clearly delocalized and couples to the WSe2 substrate despite a relatively large lattice mismatch of ∼ 11%. The latter gives rise to a surface layer derived band with a dispersion of about 0.25 eV. The basically different electronic interaction of these states across the interface is discussed in context with ab initio electronic structure calculations based on the local–density approximation employing nonlocal, normconserving pseudopotentials together with Gaussian orbital basis sets. A theoretical analysis considers the orbital character of the involved HfS2 valence states and the WSe2 band responsible for the electronic coupling.