Photon emission induced by elastic exciton--carrier scattering in semiconductor quantum wells

TL;DR

This paper investigates photon emission caused by elastic exciton-carrier scattering in semiconductor quantum wells, emphasizing the dominant role of fermion exchange effects in the scattering process and resulting photon emission rates.

Contribution

It introduces a detailed theoretical framework for exciton-carrier scattering including exchange effects and calculates photon emission rates at room temperature in quantum wells.

Findings

Fermion exchange dominates exciton-carrier scattering.

Photon emission rates are quantified for different materials.

Exchange effects significantly influence recombination processes.

Abstract

We present a study of the elastic exciton--electron ($X-e^-$) and exciton--hole ($X-h$) scattering processes in semiconductor quantum wells, including fermion exchange effects. The balance between the exciton and the free carrier populations within the electron-hole plasma is discussed in terms of ionization degree in the nondegenerate regime. Assuming a two-dimensional Coulomb potential statically screened by the free carrier gas, we apply the variable phase method to obtain the excitonic wavefunctions, which we use to calculate the 1$s$ exciton--free carrier matrix elements that describe the scattering of excitons into the light cone where they can radiatively recombine. The photon emission rates due to the carrier-assisted exciton recombination in semiconductor quantum-wells (QWs) at room temperature and in a low density regime are obtained from Fermi's golden rule, and studied for mid-gap and wide-gap materials. The quantitative comparison of the direct and exchange terms of the scattering matrix elements shows that fermion exchange is the dominant mechanism of the exciton--carrier scattering process. This is confirmed by our analysis of the rates of photon emission induced by electron-assisted and hole-assisted exciton recombinations.