Competition between the electronic and phonon-mediated scattering channels in the out-of-equilibrium carrier dynamics of semiconductors: an ab-initio approach

TL;DR

This paper presents an ab-initio study of carrier dynamics in silicon, analyzing the competition between electron-electron and electron-phonon scattering channels using advanced many-body techniques and simplified collision approximations.

Contribution

It introduces a fully ab-initio approach to simulate out-of-equilibrium carrier dynamics, combining the Baym-Kadanoff equations with a simplified collision approximation for realistic systems.

Findings

Carrier dynamics linked to equilibrium self-energies

Balance between e-e and e-p scattering depends on carrier energies

Method overcomes numerical challenges in real-time simulations

Abstract

The carrier dynamics in bulk Silicon, a paradigmatic indirect gap semiconductor, is studied by using the Baym-Kadanoff equations. Both the electron--electron(e-e) and electron--phonon(e-p) self--energies are calculated fully ab-initio by using a semi-static GW approximation in the e-e case and a Fan self-energy in the e-p case. By using the generalized Baym-Kadanoff ansatz the two-time evolution is replaced by the only dynamics on the macroscopic time axis. The enormous numerical difficulties connected with a real-time simulation of realistic systems is overcame by using a completed collision approximation that further simplifies the memory effects connected to the time evolution. The carrier dynamics is shown to reduce in such a way to have stringent connections to the well-known equilibrium electron-electron and electron-phonon self-energies. This link allows to use general arguments to motivate the relative balance between the e-e and e-p scattering channels on the basis of the carrier energies.