Physikalische Chemie - Direktor: Prof. Dr. Martin Wolf
Department Online Seminar
Chair: Melanie Müller

Tuesday, October 6, 2020, 3:00 pm
Bruno Schuler
Nanotech@surfaces Laboratory, EMPA, Dübendorf, Switzerland &
Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, USA
Designing Atomic Quantum Defects in 2D Semiconductors
2D materials are an exciting host to engineer atomic quantum systems by chemical design rules. In this talk, I will give an overview on our efforts to design defect systems in monolayer transition metal dichalcogenides (TMDs) by means of chemical doping, He ion beam bombardment and atomic manipulation. Individual point defects in such samples were studied by means of high-resolution scanning probe microscopy (see Fig. 1). [1-8]
We directly resolve the discrete electronic spectrum of single dopants in a charge neutral or ionized state and map out their associated defect orbitals [1-5]. Different types of defects reveal the interplay between chemical impurity states [1,3], multi-valley hydrogenic bound states [4], and electron-phonon coupling [1,8] at reduced dimensions. In particular, we demonstrate the atomically controlled generation of magnetic carbon radical ions (CRIs) in synthetic TMDs [8].
We also show electrically driven photon emission from individual defects [7]. Atomically resolved luminescence maps from single sulfur vacancy defects are presented. The widely tunable optical emission generated by charge carrier injection into localized defect states in a 2D material is a powerful platform for electrically driven single-photon emission.

[1] B. Schuler et al., Phys. Rev. Lett. 123, 076801 (2019)
[2] S. Barja et al., Nat. Commun. 10, 3382 (2019)
[3] B. Schuler et al., ACS Nano 13, 10520 (2019)
[4] M. Aghajanian et al., Phys. Rev. B 101, 081201(R) (2020)
[5] E. Mitterreiter et al., Nano Lett. 20, 4437 (2020)
[6] K. Cochrane et al., 2D Mater. 7, 031003 (2020)
[7] B. Schuler et al., Sci. Adv. in press (2020)
[8] K. Cochrane et al., arxiv: 2008.12196

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