Dresden 2020 – scientific programme

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DS: Fachverband Dünne Schichten

DS 16: 2D semiconductors and van der Waals heterostructures III (joint session HL/DS)

DS 16.1: Invited Talk

Tuesday, March 17, 2020, 09:30–10:00, POT 81

Radiative Lifetime and Fine Structure of Excitons in Transition Metal Dichalcogenide Monolayers — •Xavier Marie — Université de Toulouse, LPCNO, INSA-CNRS-UPS, Toulouse, France

Optical properties of atomically thin transition metal dichalcogenides are controlled by robust excitons characterized by a very large oscillator strength [1,2,3]. Encapsulation of monolayers such as MoSe2 in hexagonal boron nitride (hBN) yields narrow optical transitions approaching the homogeneous exciton linewidth [4,5]. We demonstrate that the exciton radiative rate in these van der Waals heterostructures can be tailored by a simple change of the hBN encapsulation layer thickness as a consequence of the Purcell effect [6].

The time-resolved photoluminescence measurements together with cw reflectivity and photoluminescence experiments show that the neutral exciton spontaneous emission time can be tuned by one order of magnitude depending on the thickness of the surrounding hBN layers.

I will also discuss recent results on the fine structure of excitons in MoSe2 and MoS2 monolayers.

[1] G. Wang et al, Rev. Mod. Phys. 90, 021001 (2018) [2] D. Lagarde et al, PRL 112, 047401 (2014) [3] C. Robert et al, PRB 93, 205423 (2016) [4] F. Cadiz et al, PRX 7, 021026 (2017) [5] G. Wang et al, PRL 119, 047401 (2017) [6] H.H. Fang et al, PRL 123, 067401 (2019)