Negative diffusion of excitons in quasi-two-dimensional systems

Abstract

We show how two different mobile-immobile type models explain the observation of negative diffusion of excitons reported in experimental studies in quasi-two-dimensional semiconductor systems. The main reason for the effect is the initial trapping and a delayed release of free excitons in the area close to the original excitation spot. The density of trapped excitons is not registered experimentally. Hence, the signal from the free excitons alone includes the delayed release of not diffusing trapped particles. This is seen as the narrowing of the exciton density profile or decrease of mean-squared displacement which is then interpreted as a negative diffusion. The effect is enhanced with the increase of recombination intensity as well as the rate of the exciton-exciton binary interactions.

14 pages, 8 figures

References in corpus (2)

• Decoherence of Excitons in Multichromophore Systems: Thermal Line Broadening and Destruction of Superradiant Emission
• Rate equations, spatial moments, and concentration profiles for mobile-immobile models with power-law and mixed waiting time distributions

Cited by in corpus (4)

• Electromagnetic field assisted exciton diffusion in moiré superlattices
• Photoluminescence decay of mobile carriers influenced by imperfect quenching at particle surfaces with subdiffusive spread
• Viscous hydrodynamics of excitons in van der Waals heterostructures
• Effect of spin-dependent tunneling and intervalley scattering in magnetic-semiconductor van der Waals heterostructures on exciton and trion polarization