Spatiotemporal dynamics of free and bound excitons in CVD-grown MoS$_2$ monolayer
Appl. Phys. Lett. 119, 113102 (2021) We study photoluminescence (PL) spectra and exciton dynamics of MoS$_2$ monolayer (ML) grown by the chemical vapor deposition technique. In addition to the usual direct A-exciton line we observe a low-energy line of bound excitons dominating the PL spectra at low...
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Zusammenfassung: | Appl. Phys. Lett. 119, 113102 (2021) We study photoluminescence (PL) spectra and exciton dynamics of MoS$_2$
monolayer (ML) grown by the chemical vapor deposition technique. In addition to
the usual direct A-exciton line we observe a low-energy line of bound excitons
dominating the PL spectra at low temperatures. This line shows unusually strong
redshift with increase in the temperature and submicrosecond time dynamics
suggesting indirect nature of the corresponding transition. By monitoring
temporal dynamics of exciton PL distribution in the ML plane we observe
diffusive transport of A-excitons and measure the diffusion coefficient up to
$40$~cm$^2$/s at elevated excitation powers. The bound exciton spatial
distribution spreads over tens of microns in $\sim 1$ $\mu$s. However this
spread is subdiffusive, characterized by a significant slowing down with time.
The experimental findings are interpreted as a result of the interplay between
the diffusion and Auger recombination of excitons. |
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DOI: | 10.48550/arxiv.2108.10230 |