Coherence Length of Excitons in a Semiconductor Quantum Well

TL;DR

This paper experimentally measures the coherence length of excitons in ZnSe quantum wells, revealing it to be significantly larger than the exciton de Broglie wavelength and influenced by static disorder.

Contribution

First experimental determination of exciton coherence length in semiconductors using combined spatially resolved photoluminescence and phonon sideband spectroscopy.

Findings

Coherence length of 300-400 nm in ZnSe quantum wells

Coherence length decreases with increasing exciton kinetic energy

Static disorder significantly affects coherence length measurements

Abstract

We report on the first experimental determination of the coherence length of excitons in semiconductors using the combination of spatially resolved photoluminescence with phonon sideband spectroscopy. The coherence length of excitons in ZnSe quantum wells is determined to be 300 ~ 400 nm, about 25 ~ 30 times the exciton de Broglie wavelength. With increasing exciton kinetic energy, the coherence length decreases slowly. The discrepancy between the coherence lengths measured and calculated by only considering the acoustic phonon scattering suggests an important influence of static disorder.