Influence of Coulomb and Phonon Interaction on the Exciton Formation Dynamics in Semiconductor Heterostructures

TL;DR

This paper presents a microscopic theory of exciton formation in semiconductor heterostructures, highlighting the roles of Coulomb and phonon interactions and revealing different timescales for correlation buildup and exciton formation.

Contribution

It introduces a comprehensive microscopic model that includes all relevant correlations up to the four-point level, providing new insights into exciton formation dynamics.

Findings

Coulomb correlations develop rapidly within picoseconds.

Phonon interactions lead to exciton formation over nanoseconds.

The theory fully accounts for the fermionic substructure of excitons.

Abstract

A microscopic theory is developed to analyze the dynamics of exciton formation out of incoherent carriers in semiconductor heterostructures. The carrier Coulomb and phonon interaction is included consistently. A cluster expansion method is used to systematically truncate the hierarchy problem. By including all correlations up to the four-point (i.e. two-particle) level, the fundamental fermionic substructure of excitons is fully included. The analysis shows that the exciton formation is an intricate process where Coulomb correlations rapidly build up on a picosecond time scale while phonon dynamics leads to true exciton formation on a slow nanosecond time scale.