Dynamics of trion formation in GaAs quantum wells

TL;DR

This paper introduces a double channel mechanism for trion formation in GaAs quantum wells, explaining coexistence of charged excitons without excess carriers and analyzing experimental photoluminescence data.

Contribution

It presents a novel model for trion formation via bi- and tri-molecular processes and applies it to interpret time-resolved photoluminescence experiments.

Findings

Charged excitons coexist without excess carriers.

The model explains the radiative decay time discrepancy.

Photoluminescence contributions are clearly separated and analyzed.

Abstract

We propose a double channel mechanism for the formation of charged excitons (trions); they are formed through bi- and tri-molecular processes. This directly implies that both negatively and positively charged excitons coexist in a quantum well, even in the absence of excess carriers. The model is applied to a time-resolved photoluminescence experiment performed on a very high quality InGaAs quantum well sample, in which the photoluminescence contributions at the energy of the trion, exciton and at the band edge can be clearly separated and traced over a broad range of times and densities. The unresolved discrepancy between the theoretical and experimental radiative decay time of the exciton in a doped semiconductor is explained.