Optical transitions and energy relaxation of hot carriers in Si nanocrystals

TL;DR

This paper theoretically investigates the energy relaxation mechanisms of hot carriers in silicon nanocrystals, highlighting the dominance of phonon emission and the role of Auger-like processes.

Contribution

It introduces an atomistic tight binding model to analyze hot carrier dynamics, emphasizing the interplay of radiative, Auger-like, and phonon-assisted processes in silicon nanocrystals.

Findings

Auger-like processes are the fastest energy exchange mechanism.

Single optical phonon emission governs energy relaxation.

Energy conservation limits single-phonon processes in small nanocrystals.

Abstract

Dynamics of hot carriers confined in Si nanocrystals is studied theoretically using atomistic tight binding approach. Radiative, Auger-like and phonon-assisted processes are considered. The Auger-like energy exchange between electrons and holes is found to be the fastest process in the system. However the energy relaxation of hot electron-hole pair is governed by the single optical phonon emission. For a considerable number of states in small nanocrystals single-phonon processes are ruled out by energy conservation law.