Article ID Journal Published Year Pages File Type
7938823 Superlattices and Microstructures 2018 28 Pages PDF
Abstract
Monolayer Tungsten Disulphide (WS2) with strongly confined 2D Wannier-Mott excitons exhibits a large binding energy and oscillator strength. This monolayer is currently emerging as a good candidate for studying strong light-matter coupling at high temperature. Here, we investigate the formation of exciton-polaritons in a monolayer WS2 based semiconductor microcavity under non-resonant excitation. Our results show that the cavity detuning changes from negative to positive values over a temperature range of 130-230 K, which allow the tuning of polariton dispersion. The Hopfield coefficient show that the Upper branch (UP) can be tuned from a more excitonlike (130 K), to a more photonlike (230 K) at small wave vector k. Thus, the UP states have a faster lifetime which enhances the relaxation mechanisms towards lower polariton (LP) states. A Rabi splitting of 40 meV is observed, which corresponds to energy of longitudinal optical (LO) phonon. To show how polaritons states are populated, we investigate a semiclassical model that treats the temporal dynamics of polaritons in which LO phonon-assisted polariton emission is taken into account. The results reveals that the UP occupation starts to decrease, for increasing the occupation factor in the LP branch.
Related Topics
Physical Sciences and Engineering Materials Science Electronic, Optical and Magnetic Materials
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