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HL: Fachverband Halbleiterphysik
HL 26: 2D Materials and Heterostructures: Quantum Emitters and Defects
HL 26.2: Talk
Wednesday, March 20, 2024, 09:45–10:00, EW 201
Dephasing Dynamics in Defect Centers of Hexagonal Boron Nitride Probed by Time-Resolved Cathodoluminescence Spectroscopy — •Nahid Talebi1, Masoud Taleb1, Paul Bittorf1, Maximilian Black1, Mario Hentschel2, and Kourosh Esmaeeli Koshkoie2 — 1Institute of Experimental and Applied Physics, Kiel University, 24098 Kiel, Germany — 234th Physics Institute and Research Center SCoPE, University of Stuttgart, 70569 Stuttgart, Germany
Defect centers in hexagonal boron nitride (hBN) have been extensively explored as room-temperature single-photon sources. The electronic structures of these defects exhibit strong coupling to phonons, as evidenced by the observation of phonon sidebands in both photoluminescence and cathodoluminescence spectra, and as reported in the literature. However, the dynamics of the electron-phonon coupling as well as phonon-mediated dephasing of the color centers in hBN have remained unexplored. Here, we apply a novel time-resolved CL spectroscopy technique (Nature Physics 19, 869*876 (2023)) to explore the population decay to phonon states and the dephasing time T2 with sub-femtosecond time resolution. We demonstrate an ultrafast dephasing time of only 200 fs and a population decay of approximately 700 fs at room temperature, in contrast with all-optical time-resolved photoluminescence techniques that report a decay of a few nanoseconds. This behavior is attributed to an efficient excitation of coherent phonons polaritons in hBN with electron beams that results in faster dephasing of electronic transitions.