Carrier dynamics and optical gain in InP-based quantum dots

Filipe Velosa; Hannes van Avermaet; Pieter Schiettecatte; Leila Mingabudinova; Pieter Geiregat; Zeger Hens

doi:10.1117/12.2593941

9 September 2021 Carrier dynamics and optical gain in InP-based quantum dots

Filipe Velosa, Hannes van Avermaet, Pieter Schiettecatte, Leila Mingabudinova, Pieter Geiregat, Zeger Hens

Proceedings Volume 11799, Physical Chemistry of Semiconductor Materials and Interfaces XX; 117990V (2021) https://doi.org/10.1117/12.2593941
Event: SPIE Nanoscience + Engineering, 2021, San Diego, California, United States

Abstract

InP colloidal quantum dots have become widespread in luminescent colour conversion however further studies are necessary to understand the origin of the emitting state. Additionally, reports on optical gain are scarce and lack follow-up research. In this paper, we study the properties of InP/ZnSe and InP/ZnSe/ZnS quantum dots with Transient Absorption Spectroscopy. We propose a state-filling model were the band-edge bleach can be interpreted as the filling of the conduction and valence band edge states by delocalized holes and electrons. According to this interpretation, optical gain should be observed once the average exciton density is larger than 1. We explain this lower than expected threshold and the properties of the observed stimulated emission band by acknowledging that Stokes shift is the main spectral shift. The proposed exciton-phonon coupling leads to a unique mechanism where the stimulated emission band results from the counteraction between the absorption and photoluminescence bands. To fully take advantage of this mechanism, we propose that InP-based QDs with narrower emission lines and slower Auger recombination at higher pump intensities are needed.

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Citation Download Citation

Filipe Velosa, Hannes van Avermaet, Pieter Schiettecatte, Leila Mingabudinova, Pieter Geiregat, and Zeger Hens "Carrier dynamics and optical gain in InP-based quantum dots", Proc. SPIE 11799, Physical Chemistry of Semiconductor Materials and Interfaces XX, 117990V (9 September 2021); https://doi.org/10.1117/12.2593941

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