Moritz Fischer: Luminescent defects in hBN activated by oxygen plasma

DTU Fotonik  Technical University of Denmark  2800 Kgs. Lyngby, Denmark  In the wide range of two-dimensional materials such as graphene and transition metal dichalcogenides, hexagonal boron nitride (hBN) provides a large band gap of around 6 eV. [1] This enables hBN to host defects with energy states deep inside in the electronic band gap, which are even active at room temperature. Using a state-of-the-art optical photoluminescence setup in mapping mode, we identified defects in multilayer hBN. These defects were preliminary activated by oxygen plasma or thermal annealing. We could classify the emitters by two groups of defects reported in literature. [2] One main characteristics of those two groups is the coupling to optical phonons: one group shows pronounced phonon side bands and the other one show weak phonon side bands. Further explorations of defects in hBN will pave the way to a better understanding of the coupling mechanism between phonons and defects in low-dimensional materials. These studies have been carried out within the Center of Nanostructured Graphene (CNG).   [1] Tran T.T., Bray K., Ford M. J., Toth M., Aharonovich I. Quantum emission from hexagonal boron nitride monolayers. Nature Nanotech. 11, 37-41 (2016). [2] Tran T.T., et al. Robust Multicolor Single Photon Emission from Point Defects in Hexagonal Boron Nitride, ACS Nano 10, 7331-7338 (2016). [3] M. Fischer et al. (in preparation, 2018). Moritz Fischer is currently a PhD student at the Technical University of Denmark in Copenhagen. His research focuses on the optical properties of two-dimensional materials such as hexagonal boron nitride. He received his B.Sc. and M.Sc. degree in Physics from the University of Stuttgart in Germany in the years 2015 and 2018. Afterwards he started his PhD on Single-Photon Emitters in 2D Materials in the Structured Electromagnetic Materials group, located at the Technical University of Denmark.