Friedel oscillations as an origin of Mahan exciton/Fermi edge singularity phenomena in optical spectra of degenerated semiconductors

TL;DR

This paper explores how Friedel oscillations influence Mahan exciton and Fermi edge singularity phenomena in the optical spectra of degenerate semiconductors, highlighting the role of electron density oscillations in recombination processes.

Contribution

It proposes a qualitative relationship between Friedel oscillations and many-body optical phenomena, emphasizing the importance of hole mass in these effects.

Findings

Friedel oscillations can modify valence band hole wavefunctions.

Finite hole mass is crucial for Mahan enhancement.

Electron density oscillations impact recombination processes.

Abstract

We point out at the possible relationship between the two many-body phenomena: Friedel oscillations and Mahan exciton/Fermi edge singularity in a recombination process of a localized valence band hole with a degenerate electron system. It is qualitatively described that the oscillating electron density around the screened potential of a neutral acceptor can modify the wavefunction of the valence band hole and thus promote its recombination with electrons near Fermi-surface. The role of a finite hole mass for the net balance of the two hole energies: the kinetic energy and Coulomb attraction to the degenerate electron system, - is discussed and explicitly shown to be crucial for the occurrence of Mahan enhancement phenomena.