Long-Distance Diffusion of Excitons in Double Quantum Well Structures

TL;DR

This paper reports on measurements of exciton diffusion in double quantum wells, revealing a strong dependence of diffusion coefficients on well width and confirming exciton motion as the transport mechanism.

Contribution

It provides the first detailed measurements of exciton diffusion over long distances in double quantum wells, highlighting the well-width dependence and the similarity to electron diffusion.

Findings

Excitons can live up to 30 microseconds and diffuse up to 500 micrometers.

Diffusion coefficients strongly depend on well width following a power law.

Transport occurs primarily through exciton motion, not other mechanisms.

Abstract

In this Letter we report on lateral diffusion measurements of excitons at low temperature in double quantum wells of various widths. The structure is designed so that excitons live up to 30 $\mu$s and diffuse up to 500 $\mu$m. Particular attention is given to establishing that the transport occurs by exciton motion. The deduced exciton diffusion coefficients have a very strong well-width dependence, and obey the same power law as the diffusion coefficient for electrons.