A Joint ALS/Foundry Seminar
Date: Tuesday, May 17, 2022
Time: 11:00 am
Location: Chemla Room (67-3111) and Zoom
Talk Title: Engineering the Optical Properties of Layered Semiconductors
Layered materials such as the transition metal dichalcogenides (TMD) MoS2 and WSe2 show strong and tunable light absorption and very surprising non-linear optical properties such as strong second harmonic generation. In this seminar we show several approaches that allow tuning of the optical properties in atomically thin devices based on our knowledge of the fundamental optical transitions governed by excitons (electron-hole-pairs). We show tuning of the second harmonic generation efficiency in TMD homo- and heterobilayers by several orders of magnitude, mediated by interlayer excitons and layer hybridization .
Tuning optical properties is also possible staying in the monolayer limit if innovative growth processes are used. Here we show new results on Janus monolayer structures SeMoS with different top and bottom chalcogen atoms. We also show exciton spectroscopy and exciton diffusion in hBN encapsulated MoSe2-WSe2 lateral monolayer heterostructures grown by chemical vapor deposition.
This work is based on many fruitful collaborations with partners such as the NIMS Tsukuba, FSU Jena, University of Basel and the Ioffe Institue St. Petersburg.
1. S. Shree et al, Nature Communications 2021 https://www.nature.com/articles/s41467-021-27213-8
2. I. Paradisanos et al, Physical Review B 2022 https://journals.aps.org/prb/abstract/10.1103/PhysRevB.105.115420
Bernhard Urbaszek is a Director of Research at CNRS. He has co-authored more than 120 papers in international journals and is teaching Solid State Physics, Optoelectronics and Quantum Mechanics at INSA Toulouse. He is the principal investigator of the ERC project OptoDNPcontrol (2013-2018) and coordinator of ANR projects (2D-van-der-Waals–Spin) and Marie Curie ITN nodes (SpinNano; 4Photon).