SKM 2021 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 19: Poster Session IV

HL 19.17: Poster

Thursday, September 30, 2021, 13:30–16:30, P

Understanding surface properties of CsK₂Sb from first principles — •Richard Schier¹, Holger-Dietrich Saßnick², and Caterina Cocchi² — ¹Humboldt-Universität zu Berlin, Physics Department and IRIS Adlershof, 12489 Berlin — ²Carl von Ossietzky Universität Oldenburg, Institute of Physics, 26129 Oldenburg

Among the most promising compounds for next-generation photocathodes in particle accelerators, CsK₂Sb is regarded with particular interest. While first-principles calculations have recently contributed to gain insight into the bulk characteristics of this system [1], for most physical processes related to photoemission, surface properties are essential. To fill this gap, we use density functional theory to simulate and analyze the stability and the electronic properties of the low-Miller-index surfaces of CsK₂Sb. After assessing the formation energies, we calculate ionization potential (IP), band structure, and projected density of states (PDOS). Depending on the surface, we find IPs ranging from 2.2 eV to 3.4 eV. The computed band structures reveal that CsK₂Sb surfaces can exhibit either direct and indirect bandgaps, and in some specific cases they can even become metallic. The calculated PDOS offers insight into the atomic contributions to the bands around the Fermi energy.

[1] C. Cocchi et al., J. Phys: Condens. Matter 31, 014002 (2019)