Su Ying Quek1
National University of Singapore1
Su Ying Quek1
National University of Singapore1
Quantum emitters in the form of point defects in 2D materials are of interest as scalable single photon sources for photonics-based quantum technologies. It is important to know the optical signatures of intrinsic defects, but also critical to be able to controllably synthesize quantum emitters with desirable and known optical properties. In this work, we use state-of-the-art first principles calculations to elucidate the structure-property relations of quantum emitters in the wide-band-gap hexagonal boron nitride (hBN) layer, as well as in transition metal dichalcogenide (TMD) monolayers. Defects in hBN can be controllably created by carbon implantation and electron or ion bombardment. We present the photophysical properties of defects derived from boron vacancies and carbon impurities [1], as well as preliminary results on other point defects created by the electron or ion bombardment process. Comparisons are made with recent experiments. In the second part of the talk, we discuss the optical properties of unintended oxygen-related defects and intentional substitutional defects in TMDs. We find that chalcogen vacancies in WSe<sub>2</sub> are readily passivated by oxygen, and oxygen interstitials are a possible source of single photons in WSe<sub>2</sub> [2]. For both Re [3] and Nb dopants in WS<sub>2</sub>, we present theoretical and experimental evidence of optical defect-to-bulk state transitions that partially preserve the valley polarization. We will also touch on preliminary results on THz quantum emitters in TMDs.<br/> <br/>[1] Y. Chen and S. Y. Quek, “Photophysical Characteristics of Boron Vacancy-Derived Defect Centers in Hexagonal Boron Nitride”, Journal of Physical Chemistry C, 125, 21791 (2021)<br/> <br/>[2] Y. J. Zheng, Y. Chen, Y. L. Huang, P. K. Gogoi, M.-Y. Li, L.-J. Li, P. E. Trevisanutto, Q. Wang, S. J. Pennycook, A. T. S. Wee, S. Y. Quek, “Point Defects and Localized Excitons in 2D WSe<sub>2</sub>”, ACS Nano 13, 6050 (2019)<br/> <br/>[3] L. Loh, Y. Chen, J. Wang, X. Yin, C.S. Tang, Q. Zhang, K. Watanabe, T. Taniguchi, A.T.S. Wee, M. Bosman, S.Y. Quek, and G. Eda, “Impurity-Induced Emission in Re-Doped WS<sub>2</sub> Monolayers”, Nano Letters, 21, 5293 (2021)<br/> <br/><b>Funding Acknowledgement:</b><br/>Supported by the Singapore Ministry of Education under grant number MOE2018-T3-1-005.