Phonon decay in silicon nanocrystals

TL;DR

This paper calculates the decay rate of optical phonons into smaller energy phonons in silicon nanocrystals, highlighting its potential role in energy relaxation and hot carrier photoluminescence.

Contribution

It provides a theoretical calculation of phonon decay rates in silicon nanocrystals, linking anharmonic decay to carrier relaxation and luminescence phenomena.

Findings

Decay rate of 1 to 10 ps for phonon decay.

Phonon decay influences energy relaxation in nanocrystals.

Relevance to hot carrier photoluminescence observed experimentally.

Abstract

The decay of the optical phonon into the two phonons of smaller energy is calculated for Si nanocrystals. The rate of the process is in the range of 1 to 10 ps. Such anharmonic phonon decay may control the energy relaxation rate of excited carriers in Si/SiO$_2$ nanocrystals. Relevance of the phonon decay to the experimentally observed hot carrier photoluminescence is discussed.