Drift-diffusion model of the fragmentation of the external ring structure in the photoluminescence pattern of indirect excitons in coupled quantum wells

TL;DR

This paper introduces a classical non-linear diffusion model that explains the formation and fragmentation of external rings in photoluminescence patterns of indirect excitons in coupled quantum wells, highlighting Coulomb interactions and temperature effects.

Contribution

It presents a novel classical diffusion model incorporating Coulomb interactions to explain ring fragmentation in indirect excitons, aligning with experimental observations.

Findings

Fragmentation persists above quantum degeneracy temperature.

Coulomb interactions induce pattern formation.

Model reproduces observed ring fragmentation.

Abstract

Under optical excitation, coupled quantum wells are known to reveal fascinating features in the photoluminescence pattern originating from dipole orientated indirect excitons. The appearance of an external ring has been attributed to macroscopic charge separation in the quantum well plane. We present a classical model of non-linear diffusion to account for the observed fragmentation of the external ring into a periodic array of islands. The model incorporates the Coulomb interactions between electrons, holes and indirect excitons. At low temperatures, these interactions lead to pattern formation similar to the experimentally observed ring fragmentation. The fragmentation is found to persist to temperatures above the quantum degeneracy temperature of indirect excitons.