Dresden 2020 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 21: 2D Materials II: Electronic Structure, Excitations, etc. (joint session O/CPP/HL)
HL 21.5: Talk
Monday, March 16, 2020, 16:00–16:15, WIL C107
Final-State Effects in Photoemission from Black Phosphorus — •Charlotte E. Sanders1, Irene Aguilera2, Klara Volkaert3, Deepnarayan Biswas3, Marco Bianchi3, and Philip Hofmann3 — 1Central Laser Facility, STFC Rutherford Appleton Laboratory, Harwell OX11 0QX, UK — 2Institute of Energy Research - Photovoltaic, Forschungszentrum Jülich, D-52425 Jülich, Germany — 3Department of Physics and Astronomy, Aarhus University, 8000-C Aarhus, Denmark
Intrinsically doped bulk black phosphorus, although a van der Waals layered crystal, has nontrivial interlayer interactions and out-of-plane dispersing (kz) electronic states, with a direct bandgap at the Z point of the three-dimensional (3D) Brillouin zone. The material’s 3D character is related to key properties such as the thickness dependence of the bandgap in thin films and the tunability of the bandgap by strain and electric field. Interestingly, studies from angle-resolved photoemission spectroscopy (ARPES) of the kz dispersion reveal intensity modulations near the Fermi level that are difficult to interpret in terms of the valence band dispersion predicted by theory. They have been attributed to surface-resonant states [1,2]. However, on the basis of density functional theory calculations and ARPES data acquired across a broad photon energy range, we suggest here an alternative interpretation based on final-state effects. The results call attention to the meaning of the free-electron-like final-state assumption and to the limits of its applicability. [1] PRB 90 (2014) 085101. [2] PRB 93 (2016) 075207.