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HL: Fachverband Halbleiterphysik
HL 26: 2D Materials and Heterostructures: Quantum Emitters and Defects
HL 26.5: Vortrag
Mittwoch, 20. März 2024, 10:30–10:45, EW 201
Excited state geometry relaxation of point defects in monolayer hexagonal boron nitride — •Alexander Kirchhoff, Thorsten Deilmann, and Michael Rohlfing — University of Münster, Institute of Solid State Theory, Wilhelm-Klemm-Straße 10, 48149 Münster
Point defects in hexagonal boron nitride (hBN) are often discussed as single-photon emitters for quantum technologies. Understanding the dependence of electronic and optical properties on the geometry might help to identify the atomic structure of the defects and is also crucial in order to make these emitters applicable. Here, we study three defects in a monolayer of hBN, namely CBVN, CBCN and CBON, from an ab initio approach. We use (constrained) density functional theory to obtain optimal geometries of the electronic ground state and the first excited state, and then refine quasi-particle energies and optical excitation energies using a GW and BSE based appraoch. All three defect systems host transitions between deep lying defect states. We find the lowest defect exciton of CBCN at ∼ 4 eV and for the other two defects at ∼ 2 eV with significant Stokes shifts of 0.2 eV and 0.7 eV, respectively.
Keywords: hexagonal boron nitride; ab inito; GW; BSE; point defects