Traces of stimulated bosonic exciton-scattering in semiconductor luminescence

TL;DR

This study provides experimental evidence of stimulated bosonic exciton scattering in semiconductor quantum wells, revealing polarization effects consistent with bosonic enhancement but not indicating a full Bose-Einstein condensate.

Contribution

It demonstrates stimulated exciton scattering signatures in luminescence and distinguishes these from a true Bose-Einstein condensate in semiconductor systems.

Findings

Observation of circularly polarized biexciton luminescence due to bosonic enhancement

Experimental data aligns with many-body theory of stimulated scattering

No evidence of a fully condensed BEC-like state was found

Abstract

We observe signatures of stimulated bosonic scattering of excitons, a precursor of Bose-Einstein-Condensation (BEC), in the photoluminescence of semiconductor quantum wells. The optical decay of a spinless molecule of two excitons (biexciton) into an exciton and a photon with opposite angular momenta is subject to bosonic enhancement in the presence of other excitons. In a spin polarized gas of excitons the bosonic enhancement breaks the symmetry of two equivalent decay channels leading to circularly polarized luminescence of the biexciton with the sign opposite to the excitonic luminescence. Comparison of experiment and many body theory proves stimulated scattering of excitons, but excludes the presence of a fully condensed BEC-like state.