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HL: Fachverband Halbleiterphysik

HL 49: Quantum Emitters in 2D Semiconductors

HL 49.1: Hauptvortrag

Donnerstag, 12. März 2026, 16:15–16:45, POT/0081

Phonon-mediated nonlinearity and defects in hexagonal boron nitride — •Nahid Talebi — Institute of Experimental and Applied Physics, Kiel University, Germany

Hexagonal boron nitride (hBN) hosts a rich phonon landscape whose strong oscillator strengths in the first and second Reststrahlen bands give rise to negative permittivity and support the propagation of hyperbolic phonon polaritons. In this work, we show that these phonon modes can mediate highly efficient down-conversion of optical excitation, enabling strong coupling to point defects and facilitating the coherent excitation of their electronic states. We further demonstrate that such defect states in hBN can couple efficiently to excitons in hybrid hBN*perovskite structures, establishing a robust exciton*defect interaction channel. Remarkably, we find that excitonic energy can be transported over distances up to 150 micrometers through incoherent hopping across a defect network within hBN. By combining spatially and spectrally resolved photoluminescence and cathodoluminescence spectroscopy, we identify the mechanisms governing coherent and incoherent defect excitation and reveal the interplay and strong coupling among excitons, defects, and phonons in hBN. These insights establish hBN as a versatile platform for phonon-assisted light*matter interactions and long-range energy transport in hybrid quantum nanophotonic systems.

Keywords: hexagonal boron nitride; 2D perovskite; photoluminescence; cathodoluminescence; defects